changeset 711:df88aee35bb9 feature/selectable_tests

Switch to _test.jl suffix
author Jonatan Werpers <jonatan@werpers.com>
date Sat, 20 Feb 2021 20:45:40 +0100
parents 44fa9a171557
children de2df1214394
files test/DiffOps/DiffOps_test.jl test/DiffOps/testDiffOps.jl test/Grids/Grids_test.jl test/Grids/testGrids.jl test/LazyTensors/LazyTensors_test.jl test/LazyTensors/testLazyTensors.jl test/RegionIndices/RegionIndices_test.jl test/RegionIndices/testRegionIndices.jl test/SbpOperators/SbpOperators_test.jl test/SbpOperators/testSbpOperators.jl test/runtests.jl
diffstat 11 files changed, 1722 insertions(+), 1727 deletions(-) [+]
line wrap: on
line diff
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/DiffOps/DiffOps_test.jl	Sat Feb 20 20:45:40 2021 +0100
@@ -0,0 +1,198 @@
+using Test
+using Sbplib.DiffOps
+using Sbplib.Grids
+using Sbplib.SbpOperators
+using Sbplib.RegionIndices
+using Sbplib.LazyTensors
+
+@testset "DiffOps" begin
+#
+# @testset "BoundaryValue" begin
+#     op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+#     g = EquidistantGrid((4,5), (0.0, 0.0), (1.0,1.0))
+#
+#     e_w = BoundaryValue(op, g, CartesianBoundary{1,Lower}())
+#     e_e = BoundaryValue(op, g, CartesianBoundary{1,Upper}())
+#     e_s = BoundaryValue(op, g, CartesianBoundary{2,Lower}())
+#     e_n = BoundaryValue(op, g, CartesianBoundary{2,Upper}())
+#
+#     v = zeros(Float64, 4, 5)
+#     v[:,5] = [1, 2, 3,4]
+#     v[:,4] = [1, 2, 3,4]
+#     v[:,3] = [4, 5, 6, 7]
+#     v[:,2] = [7, 8, 9, 10]
+#     v[:,1] = [10, 11, 12, 13]
+#
+#     @test e_w  isa TensorMapping{T,2,1} where T
+#     @test e_w' isa TensorMapping{T,1,2} where T
+#
+#     @test domain_size(e_w, (3,2)) == (2,)
+#     @test domain_size(e_e, (3,2)) == (2,)
+#     @test domain_size(e_s, (3,2)) == (3,)
+#     @test domain_size(e_n, (3,2)) == (3,)
+#
+#     @test size(e_w'*v) == (5,)
+#     @test size(e_e'*v) == (5,)
+#     @test size(e_s'*v) == (4,)
+#     @test size(e_n'*v) == (4,)
+#
+#     @test collect(e_w'*v) == [10,7,4,1.0,1]
+#     @test collect(e_e'*v) == [13,10,7,4,4.0]
+#     @test collect(e_s'*v) == [10,11,12,13.0]
+#     @test collect(e_n'*v) == [1,2,3,4.0]
+#
+#     g_x = [1,2,3,4.0]
+#     g_y = [5,4,3,2,1.0]
+#
+#     G_w = zeros(Float64, (4,5))
+#     G_w[1,:] = g_y
+#
+#     G_e = zeros(Float64, (4,5))
+#     G_e[4,:] = g_y
+#
+#     G_s = zeros(Float64, (4,5))
+#     G_s[:,1] = g_x
+#
+#     G_n = zeros(Float64, (4,5))
+#     G_n[:,5] = g_x
+#
+#     @test size(e_w*g_y) == (UnknownDim,5)
+#     @test size(e_e*g_y) == (UnknownDim,5)
+#     @test size(e_s*g_x) == (4,UnknownDim)
+#     @test size(e_n*g_x) == (4,UnknownDim)
+#
+#     # These tests should be moved to where they are possible (i.e we know what the grid should be)
+#     @test_broken collect(e_w*g_y) == G_w
+#     @test_broken collect(e_e*g_y) == G_e
+#     @test_broken collect(e_s*g_x) == G_s
+#     @test_broken collect(e_n*g_x) == G_n
+# end
+#
+# @testset "NormalDerivative" begin
+#     op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+#     g = EquidistantGrid((5,6), (0.0, 0.0), (4.0,5.0))
+#
+#     d_w = NormalDerivative(op, g, CartesianBoundary{1,Lower}())
+#     d_e = NormalDerivative(op, g, CartesianBoundary{1,Upper}())
+#     d_s = NormalDerivative(op, g, CartesianBoundary{2,Lower}())
+#     d_n = NormalDerivative(op, g, CartesianBoundary{2,Upper}())
+#
+#
+#     v = evalOn(g, (x,y)-> x^2 + (y-1)^2 + x*y)
+#     v∂x = evalOn(g, (x,y)-> 2*x + y)
+#     v∂y = evalOn(g, (x,y)-> 2*(y-1) + x)
+#
+#     @test d_w  isa TensorMapping{T,2,1} where T
+#     @test d_w' isa TensorMapping{T,1,2} where T
+#
+#     @test domain_size(d_w, (3,2)) == (2,)
+#     @test domain_size(d_e, (3,2)) == (2,)
+#     @test domain_size(d_s, (3,2)) == (3,)
+#     @test domain_size(d_n, (3,2)) == (3,)
+#
+#     @test size(d_w'*v) == (6,)
+#     @test size(d_e'*v) == (6,)
+#     @test size(d_s'*v) == (5,)
+#     @test size(d_n'*v) == (5,)
+#
+#     @test collect(d_w'*v) ≈ v∂x[1,:]
+#     @test collect(d_e'*v) ≈ v∂x[5,:]
+#     @test collect(d_s'*v) ≈ v∂y[:,1]
+#     @test collect(d_n'*v) ≈ v∂y[:,6]
+#
+#
+#     d_x_l = zeros(Float64, 5)
+#     d_x_u = zeros(Float64, 5)
+#     for i ∈ eachindex(d_x_l)
+#         d_x_l[i] = op.dClosure[i-1]
+#         d_x_u[i] = -op.dClosure[length(d_x_u)-i]
+#     end
+#
+#     d_y_l = zeros(Float64, 6)
+#     d_y_u = zeros(Float64, 6)
+#     for i ∈ eachindex(d_y_l)
+#         d_y_l[i] = op.dClosure[i-1]
+#         d_y_u[i] = -op.dClosure[length(d_y_u)-i]
+#     end
+#
+#     function prod_matrix(x,y)
+#         G = zeros(Float64, length(x), length(y))
+#         for I ∈ CartesianIndices(G)
+#             G[I] = x[I[1]]*y[I[2]]
+#         end
+#
+#         return G
+#     end
+#
+#     g_x = [1,2,3,4.0,5]
+#     g_y = [5,4,3,2,1.0,11]
+#
+#     G_w = prod_matrix(d_x_l, g_y)
+#     G_e = prod_matrix(d_x_u, g_y)
+#     G_s = prod_matrix(g_x, d_y_l)
+#     G_n = prod_matrix(g_x, d_y_u)
+#
+#
+#     @test size(d_w*g_y) == (UnknownDim,6)
+#     @test size(d_e*g_y) == (UnknownDim,6)
+#     @test size(d_s*g_x) == (5,UnknownDim)
+#     @test size(d_n*g_x) == (5,UnknownDim)
+#
+#     # These tests should be moved to where they are possible (i.e we know what the grid should be)
+#     @test_broken collect(d_w*g_y) ≈ G_w
+#     @test_broken collect(d_e*g_y) ≈ G_e
+#     @test_broken collect(d_s*g_x) ≈ G_s
+#     @test_broken collect(d_n*g_x) ≈ G_n
+# end
+#
+# @testset "BoundaryQuadrature" begin
+#     op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+#     g = EquidistantGrid((10,11), (0.0, 0.0), (1.0,1.0))
+#
+#     H_w = BoundaryQuadrature(op, g, CartesianBoundary{1,Lower}())
+#     H_e = BoundaryQuadrature(op, g, CartesianBoundary{1,Upper}())
+#     H_s = BoundaryQuadrature(op, g, CartesianBoundary{2,Lower}())
+#     H_n = BoundaryQuadrature(op, g, CartesianBoundary{2,Upper}())
+#
+#     v = evalOn(g, (x,y)-> x^2 + (y-1)^2 + x*y)
+#
+#     function get_quadrature(N)
+#         qc = op.quadratureClosure
+#         q = (qc..., ones(N-2*closuresize(op))..., reverse(qc)...)
+#         @assert length(q) == N
+#         return q
+#     end
+#
+#     v_w = v[1,:]
+#     v_e = v[10,:]
+#     v_s = v[:,1]
+#     v_n = v[:,11]
+#
+#     q_x = spacing(g)[1].*get_quadrature(10)
+#     q_y = spacing(g)[2].*get_quadrature(11)
+#
+#     @test H_w isa TensorOperator{T,1} where T
+#
+#     @test domain_size(H_w, (3,)) == (3,)
+#     @test domain_size(H_n, (3,)) == (3,)
+#
+#     @test range_size(H_w, (3,)) == (3,)
+#     @test range_size(H_n, (3,)) == (3,)
+#
+#     @test size(H_w*v_w) == (11,)
+#     @test size(H_e*v_e) == (11,)
+#     @test size(H_s*v_s) == (10,)
+#     @test size(H_n*v_n) == (10,)
+#
+#     @test collect(H_w*v_w) ≈ q_y.*v_w
+#     @test collect(H_e*v_e) ≈ q_y.*v_e
+#     @test collect(H_s*v_s) ≈ q_x.*v_s
+#     @test collect(H_n*v_n) ≈ q_x.*v_n
+#
+#     @test collect(H_w'*v_w) == collect(H_w'*v_w)
+#     @test collect(H_e'*v_e) == collect(H_e'*v_e)
+#     @test collect(H_s'*v_s) == collect(H_s'*v_s)
+#     @test collect(H_n'*v_n) == collect(H_n'*v_n)
+# end
+
+end
--- a/test/DiffOps/testDiffOps.jl	Sat Feb 20 20:36:27 2021 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,198 +0,0 @@
-using Test
-using Sbplib.DiffOps
-using Sbplib.Grids
-using Sbplib.SbpOperators
-using Sbplib.RegionIndices
-using Sbplib.LazyTensors
-
-@testset "DiffOps" begin
-#
-# @testset "BoundaryValue" begin
-#     op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-#     g = EquidistantGrid((4,5), (0.0, 0.0), (1.0,1.0))
-#
-#     e_w = BoundaryValue(op, g, CartesianBoundary{1,Lower}())
-#     e_e = BoundaryValue(op, g, CartesianBoundary{1,Upper}())
-#     e_s = BoundaryValue(op, g, CartesianBoundary{2,Lower}())
-#     e_n = BoundaryValue(op, g, CartesianBoundary{2,Upper}())
-#
-#     v = zeros(Float64, 4, 5)
-#     v[:,5] = [1, 2, 3,4]
-#     v[:,4] = [1, 2, 3,4]
-#     v[:,3] = [4, 5, 6, 7]
-#     v[:,2] = [7, 8, 9, 10]
-#     v[:,1] = [10, 11, 12, 13]
-#
-#     @test e_w  isa TensorMapping{T,2,1} where T
-#     @test e_w' isa TensorMapping{T,1,2} where T
-#
-#     @test domain_size(e_w, (3,2)) == (2,)
-#     @test domain_size(e_e, (3,2)) == (2,)
-#     @test domain_size(e_s, (3,2)) == (3,)
-#     @test domain_size(e_n, (3,2)) == (3,)
-#
-#     @test size(e_w'*v) == (5,)
-#     @test size(e_e'*v) == (5,)
-#     @test size(e_s'*v) == (4,)
-#     @test size(e_n'*v) == (4,)
-#
-#     @test collect(e_w'*v) == [10,7,4,1.0,1]
-#     @test collect(e_e'*v) == [13,10,7,4,4.0]
-#     @test collect(e_s'*v) == [10,11,12,13.0]
-#     @test collect(e_n'*v) == [1,2,3,4.0]
-#
-#     g_x = [1,2,3,4.0]
-#     g_y = [5,4,3,2,1.0]
-#
-#     G_w = zeros(Float64, (4,5))
-#     G_w[1,:] = g_y
-#
-#     G_e = zeros(Float64, (4,5))
-#     G_e[4,:] = g_y
-#
-#     G_s = zeros(Float64, (4,5))
-#     G_s[:,1] = g_x
-#
-#     G_n = zeros(Float64, (4,5))
-#     G_n[:,5] = g_x
-#
-#     @test size(e_w*g_y) == (UnknownDim,5)
-#     @test size(e_e*g_y) == (UnknownDim,5)
-#     @test size(e_s*g_x) == (4,UnknownDim)
-#     @test size(e_n*g_x) == (4,UnknownDim)
-#
-#     # These tests should be moved to where they are possible (i.e we know what the grid should be)
-#     @test_broken collect(e_w*g_y) == G_w
-#     @test_broken collect(e_e*g_y) == G_e
-#     @test_broken collect(e_s*g_x) == G_s
-#     @test_broken collect(e_n*g_x) == G_n
-# end
-#
-# @testset "NormalDerivative" begin
-#     op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-#     g = EquidistantGrid((5,6), (0.0, 0.0), (4.0,5.0))
-#
-#     d_w = NormalDerivative(op, g, CartesianBoundary{1,Lower}())
-#     d_e = NormalDerivative(op, g, CartesianBoundary{1,Upper}())
-#     d_s = NormalDerivative(op, g, CartesianBoundary{2,Lower}())
-#     d_n = NormalDerivative(op, g, CartesianBoundary{2,Upper}())
-#
-#
-#     v = evalOn(g, (x,y)-> x^2 + (y-1)^2 + x*y)
-#     v∂x = evalOn(g, (x,y)-> 2*x + y)
-#     v∂y = evalOn(g, (x,y)-> 2*(y-1) + x)
-#
-#     @test d_w  isa TensorMapping{T,2,1} where T
-#     @test d_w' isa TensorMapping{T,1,2} where T
-#
-#     @test domain_size(d_w, (3,2)) == (2,)
-#     @test domain_size(d_e, (3,2)) == (2,)
-#     @test domain_size(d_s, (3,2)) == (3,)
-#     @test domain_size(d_n, (3,2)) == (3,)
-#
-#     @test size(d_w'*v) == (6,)
-#     @test size(d_e'*v) == (6,)
-#     @test size(d_s'*v) == (5,)
-#     @test size(d_n'*v) == (5,)
-#
-#     @test collect(d_w'*v) ≈ v∂x[1,:]
-#     @test collect(d_e'*v) ≈ v∂x[5,:]
-#     @test collect(d_s'*v) ≈ v∂y[:,1]
-#     @test collect(d_n'*v) ≈ v∂y[:,6]
-#
-#
-#     d_x_l = zeros(Float64, 5)
-#     d_x_u = zeros(Float64, 5)
-#     for i ∈ eachindex(d_x_l)
-#         d_x_l[i] = op.dClosure[i-1]
-#         d_x_u[i] = -op.dClosure[length(d_x_u)-i]
-#     end
-#
-#     d_y_l = zeros(Float64, 6)
-#     d_y_u = zeros(Float64, 6)
-#     for i ∈ eachindex(d_y_l)
-#         d_y_l[i] = op.dClosure[i-1]
-#         d_y_u[i] = -op.dClosure[length(d_y_u)-i]
-#     end
-#
-#     function prod_matrix(x,y)
-#         G = zeros(Float64, length(x), length(y))
-#         for I ∈ CartesianIndices(G)
-#             G[I] = x[I[1]]*y[I[2]]
-#         end
-#
-#         return G
-#     end
-#
-#     g_x = [1,2,3,4.0,5]
-#     g_y = [5,4,3,2,1.0,11]
-#
-#     G_w = prod_matrix(d_x_l, g_y)
-#     G_e = prod_matrix(d_x_u, g_y)
-#     G_s = prod_matrix(g_x, d_y_l)
-#     G_n = prod_matrix(g_x, d_y_u)
-#
-#
-#     @test size(d_w*g_y) == (UnknownDim,6)
-#     @test size(d_e*g_y) == (UnknownDim,6)
-#     @test size(d_s*g_x) == (5,UnknownDim)
-#     @test size(d_n*g_x) == (5,UnknownDim)
-#
-#     # These tests should be moved to where they are possible (i.e we know what the grid should be)
-#     @test_broken collect(d_w*g_y) ≈ G_w
-#     @test_broken collect(d_e*g_y) ≈ G_e
-#     @test_broken collect(d_s*g_x) ≈ G_s
-#     @test_broken collect(d_n*g_x) ≈ G_n
-# end
-#
-# @testset "BoundaryQuadrature" begin
-#     op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-#     g = EquidistantGrid((10,11), (0.0, 0.0), (1.0,1.0))
-#
-#     H_w = BoundaryQuadrature(op, g, CartesianBoundary{1,Lower}())
-#     H_e = BoundaryQuadrature(op, g, CartesianBoundary{1,Upper}())
-#     H_s = BoundaryQuadrature(op, g, CartesianBoundary{2,Lower}())
-#     H_n = BoundaryQuadrature(op, g, CartesianBoundary{2,Upper}())
-#
-#     v = evalOn(g, (x,y)-> x^2 + (y-1)^2 + x*y)
-#
-#     function get_quadrature(N)
-#         qc = op.quadratureClosure
-#         q = (qc..., ones(N-2*closuresize(op))..., reverse(qc)...)
-#         @assert length(q) == N
-#         return q
-#     end
-#
-#     v_w = v[1,:]
-#     v_e = v[10,:]
-#     v_s = v[:,1]
-#     v_n = v[:,11]
-#
-#     q_x = spacing(g)[1].*get_quadrature(10)
-#     q_y = spacing(g)[2].*get_quadrature(11)
-#
-#     @test H_w isa TensorOperator{T,1} where T
-#
-#     @test domain_size(H_w, (3,)) == (3,)
-#     @test domain_size(H_n, (3,)) == (3,)
-#
-#     @test range_size(H_w, (3,)) == (3,)
-#     @test range_size(H_n, (3,)) == (3,)
-#
-#     @test size(H_w*v_w) == (11,)
-#     @test size(H_e*v_e) == (11,)
-#     @test size(H_s*v_s) == (10,)
-#     @test size(H_n*v_n) == (10,)
-#
-#     @test collect(H_w*v_w) ≈ q_y.*v_w
-#     @test collect(H_e*v_e) ≈ q_y.*v_e
-#     @test collect(H_s*v_s) ≈ q_x.*v_s
-#     @test collect(H_n*v_n) ≈ q_x.*v_n
-#
-#     @test collect(H_w'*v_w) == collect(H_w'*v_w)
-#     @test collect(H_e'*v_e) == collect(H_e'*v_e)
-#     @test collect(H_s'*v_s) == collect(H_s'*v_s)
-#     @test collect(H_n'*v_n) == collect(H_n'*v_n)
-# end
-
-end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/Grids/Grids_test.jl	Sat Feb 20 20:45:40 2021 +0100
@@ -0,0 +1,104 @@
+using Sbplib.Grids
+using Test
+using Sbplib.RegionIndices
+
+@testset "Grids" begin
+
+@testset "EquidistantGrid" begin
+    @test EquidistantGrid(4,0.0,1.0) isa EquidistantGrid
+    @test EquidistantGrid(4,0.0,8.0) isa EquidistantGrid
+    # constuctor
+    @test_throws DomainError EquidistantGrid(0,0.0,1.0)
+    @test_throws DomainError EquidistantGrid(1,1.0,1.0)
+    @test_throws DomainError EquidistantGrid(1,1.0,-1.0)
+    @test EquidistantGrid(4,0.0,1.0) == EquidistantGrid((4,),(0.0,),(1.0,))
+
+    @testset "Base" begin
+        @test eltype(EquidistantGrid(4,0.0,1.0)) == Float64
+        @test eltype(EquidistantGrid((4,3),(0,0),(1,3))) == Int
+        @test size(EquidistantGrid(4,0.0,1.0)) == (4,)
+        @test size(EquidistantGrid((5,3), (0.0,0.0), (2.0,1.0))) == (5,3)
+    end
+
+    # dimension
+    @test dimension(EquidistantGrid(4,0.0,1.0)) == 1
+    @test dimension(EquidistantGrid((5,3), (0.0,0.0), (2.0,1.0))) == 2
+
+    # spacing
+    @test [spacing(EquidistantGrid(4,0.0,1.0))...] ≈ [(1. /3,)...] atol=5e-13
+    @test [spacing(EquidistantGrid((5,3), (0.0,-1.0), (2.0,1.0)))...] ≈ [(0.5, 1.)...] atol=5e-13
+
+    # inverse_spacing
+    @test [inverse_spacing(EquidistantGrid(4,0.0,1.0))...] ≈ [(3.,)...] atol=5e-13
+    @test [inverse_spacing(EquidistantGrid((5,3), (0.0,-1.0), (2.0,1.0)))...] ≈ [(2, 1.)...] atol=5e-13
+
+    # points
+    g = EquidistantGrid((5,3), (-1.0,0.0), (0.0,7.11))
+    gp = points(g);
+    p = [(-1.,0.)      (-1.,7.11/2)   (-1.,7.11);
+         (-0.75,0.)    (-0.75,7.11/2) (-0.75,7.11);
+         (-0.5,0.)     (-0.5,7.11/2)  (-0.5,7.11);
+         (-0.25,0.)    (-0.25,7.11/2) (-0.25,7.11);
+         (0.,0.)       (0.,7.11/2)    (0.,7.11)]
+    for i ∈ eachindex(gp)
+        @test [gp[i]...] ≈ [p[i]...] atol=5e-13
+    end
+
+    # restrict
+    g = EquidistantGrid((5,3), (0.0,0.0), (2.0,1.0))
+    @test restrict(g, 1) == EquidistantGrid(5,0.0,2.0)
+    @test restrict(g, 2) == EquidistantGrid(3,0.0,1.0)
+
+    g = EquidistantGrid((2,5,3), (0.0,0.0,0.0), (2.0,1.0,3.0))
+    @test restrict(g, 1) == EquidistantGrid(2,0.0,2.0)
+    @test restrict(g, 2) == EquidistantGrid(5,0.0,1.0)
+    @test restrict(g, 3) == EquidistantGrid(3,0.0,3.0)
+    @test restrict(g, 1:2) == EquidistantGrid((2,5),(0.0,0.0),(2.0,1.0))
+    @test restrict(g, 2:3) == EquidistantGrid((5,3),(0.0,0.0),(1.0,3.0))
+    @test restrict(g, [1,3]) == EquidistantGrid((2,3),(0.0,0.0),(2.0,3.0))
+    @test restrict(g, [2,1]) == EquidistantGrid((5,2),(0.0,0.0),(1.0,2.0))
+
+    @testset "boundary_identifiers" begin
+        g = EquidistantGrid((2,5,3), (0.0,0.0,0.0), (2.0,1.0,3.0))
+        bids = (CartesianBoundary{1,Lower}(),CartesianBoundary{1,Upper}(),
+                CartesianBoundary{2,Lower}(),CartesianBoundary{2,Upper}(),
+                CartesianBoundary{3,Lower}(),CartesianBoundary{3,Upper}())
+        @test boundary_identifiers(g) == bids
+        @inferred boundary_identifiers(g)
+    end
+
+    @testset "boundary_grid" begin
+            @testset "1D" begin
+                g = EquidistantGrid(5,0.0,2.0)
+                (id_l, id_r) = boundary_identifiers(g)
+                @test boundary_grid(g,id_l) == EquidistantGrid{Float64}()
+                @test boundary_grid(g,id_r) == EquidistantGrid{Float64}()
+                @test_throws DomainError boundary_grid(g,CartesianBoundary{2,Lower}())
+                @test_throws DomainError boundary_grid(g,CartesianBoundary{0,Lower}())
+            end
+            @testset "2D" begin
+                g = EquidistantGrid((5,3),(0.0,0.0),(1.0,3.0))
+                (id_w, id_e, id_s, id_n) = boundary_identifiers(g)
+                @test boundary_grid(g,id_w) == restrict(g,2)
+                @test boundary_grid(g,id_e) == restrict(g,2)
+                @test boundary_grid(g,id_s) == restrict(g,1)
+                @test boundary_grid(g,id_n) == restrict(g,1)
+                @test_throws DomainError boundary_grid(g,CartesianBoundary{4,Lower}())
+            end
+            @testset "3D" begin
+                g = EquidistantGrid((2,5,3), (0.0,0.0,0.0), (2.0,1.0,3.0))
+                (id_w, id_e,
+                 id_s, id_n,
+                 id_t, id_b) = boundary_identifiers(g)
+                @test boundary_grid(g,id_w) == restrict(g,[2,3])
+                @test boundary_grid(g,id_e) == restrict(g,[2,3])
+                @test boundary_grid(g,id_s) == restrict(g,[1,3])
+                @test boundary_grid(g,id_n) == restrict(g,[1,3])
+                @test boundary_grid(g,id_t) == restrict(g,[1,2])
+                @test boundary_grid(g,id_b) == restrict(g,[1,2])
+                @test_throws DomainError boundary_grid(g,CartesianBoundary{4,Lower}())
+            end
+    end
+end
+
+end
--- a/test/Grids/testGrids.jl	Sat Feb 20 20:36:27 2021 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,104 +0,0 @@
-using Sbplib.Grids
-using Test
-using Sbplib.RegionIndices
-
-@testset "Grids" begin
-
-@testset "EquidistantGrid" begin
-    @test EquidistantGrid(4,0.0,1.0) isa EquidistantGrid
-    @test EquidistantGrid(4,0.0,8.0) isa EquidistantGrid
-    # constuctor
-    @test_throws DomainError EquidistantGrid(0,0.0,1.0)
-    @test_throws DomainError EquidistantGrid(1,1.0,1.0)
-    @test_throws DomainError EquidistantGrid(1,1.0,-1.0)
-    @test EquidistantGrid(4,0.0,1.0) == EquidistantGrid((4,),(0.0,),(1.0,))
-
-    @testset "Base" begin
-        @test eltype(EquidistantGrid(4,0.0,1.0)) == Float64
-        @test eltype(EquidistantGrid((4,3),(0,0),(1,3))) == Int
-        @test size(EquidistantGrid(4,0.0,1.0)) == (4,)
-        @test size(EquidistantGrid((5,3), (0.0,0.0), (2.0,1.0))) == (5,3)
-    end
-
-    # dimension
-    @test dimension(EquidistantGrid(4,0.0,1.0)) == 1
-    @test dimension(EquidistantGrid((5,3), (0.0,0.0), (2.0,1.0))) == 2
-
-    # spacing
-    @test [spacing(EquidistantGrid(4,0.0,1.0))...] ≈ [(1. /3,)...] atol=5e-13
-    @test [spacing(EquidistantGrid((5,3), (0.0,-1.0), (2.0,1.0)))...] ≈ [(0.5, 1.)...] atol=5e-13
-
-    # inverse_spacing
-    @test [inverse_spacing(EquidistantGrid(4,0.0,1.0))...] ≈ [(3.,)...] atol=5e-13
-    @test [inverse_spacing(EquidistantGrid((5,3), (0.0,-1.0), (2.0,1.0)))...] ≈ [(2, 1.)...] atol=5e-13
-
-    # points
-    g = EquidistantGrid((5,3), (-1.0,0.0), (0.0,7.11))
-    gp = points(g);
-    p = [(-1.,0.)      (-1.,7.11/2)   (-1.,7.11);
-         (-0.75,0.)    (-0.75,7.11/2) (-0.75,7.11);
-         (-0.5,0.)     (-0.5,7.11/2)  (-0.5,7.11);
-         (-0.25,0.)    (-0.25,7.11/2) (-0.25,7.11);
-         (0.,0.)       (0.,7.11/2)    (0.,7.11)]
-    for i ∈ eachindex(gp)
-        @test [gp[i]...] ≈ [p[i]...] atol=5e-13
-    end
-
-    # restrict
-    g = EquidistantGrid((5,3), (0.0,0.0), (2.0,1.0))
-    @test restrict(g, 1) == EquidistantGrid(5,0.0,2.0)
-    @test restrict(g, 2) == EquidistantGrid(3,0.0,1.0)
-
-    g = EquidistantGrid((2,5,3), (0.0,0.0,0.0), (2.0,1.0,3.0))
-    @test restrict(g, 1) == EquidistantGrid(2,0.0,2.0)
-    @test restrict(g, 2) == EquidistantGrid(5,0.0,1.0)
-    @test restrict(g, 3) == EquidistantGrid(3,0.0,3.0)
-    @test restrict(g, 1:2) == EquidistantGrid((2,5),(0.0,0.0),(2.0,1.0))
-    @test restrict(g, 2:3) == EquidistantGrid((5,3),(0.0,0.0),(1.0,3.0))
-    @test restrict(g, [1,3]) == EquidistantGrid((2,3),(0.0,0.0),(2.0,3.0))
-    @test restrict(g, [2,1]) == EquidistantGrid((5,2),(0.0,0.0),(1.0,2.0))
-
-    @testset "boundary_identifiers" begin
-        g = EquidistantGrid((2,5,3), (0.0,0.0,0.0), (2.0,1.0,3.0))
-        bids = (CartesianBoundary{1,Lower}(),CartesianBoundary{1,Upper}(),
-                CartesianBoundary{2,Lower}(),CartesianBoundary{2,Upper}(),
-                CartesianBoundary{3,Lower}(),CartesianBoundary{3,Upper}())
-        @test boundary_identifiers(g) == bids
-        @inferred boundary_identifiers(g)
-    end
-
-    @testset "boundary_grid" begin
-            @testset "1D" begin
-                g = EquidistantGrid(5,0.0,2.0)
-                (id_l, id_r) = boundary_identifiers(g)
-                @test boundary_grid(g,id_l) == EquidistantGrid{Float64}()
-                @test boundary_grid(g,id_r) == EquidistantGrid{Float64}()
-                @test_throws DomainError boundary_grid(g,CartesianBoundary{2,Lower}())
-                @test_throws DomainError boundary_grid(g,CartesianBoundary{0,Lower}())
-            end
-            @testset "2D" begin
-                g = EquidistantGrid((5,3),(0.0,0.0),(1.0,3.0))
-                (id_w, id_e, id_s, id_n) = boundary_identifiers(g)
-                @test boundary_grid(g,id_w) == restrict(g,2)
-                @test boundary_grid(g,id_e) == restrict(g,2)
-                @test boundary_grid(g,id_s) == restrict(g,1)
-                @test boundary_grid(g,id_n) == restrict(g,1)
-                @test_throws DomainError boundary_grid(g,CartesianBoundary{4,Lower}())
-            end
-            @testset "3D" begin
-                g = EquidistantGrid((2,5,3), (0.0,0.0,0.0), (2.0,1.0,3.0))
-                (id_w, id_e,
-                 id_s, id_n,
-                 id_t, id_b) = boundary_identifiers(g)
-                @test boundary_grid(g,id_w) == restrict(g,[2,3])
-                @test boundary_grid(g,id_e) == restrict(g,[2,3])
-                @test boundary_grid(g,id_s) == restrict(g,[1,3])
-                @test boundary_grid(g,id_n) == restrict(g,[1,3])
-                @test boundary_grid(g,id_t) == restrict(g,[1,2])
-                @test boundary_grid(g,id_b) == restrict(g,[1,2])
-                @test_throws DomainError boundary_grid(g,CartesianBoundary{4,Lower}())
-            end
-    end
-end
-
-end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/LazyTensors/LazyTensors_test.jl	Sat Feb 20 20:45:40 2021 +0100
@@ -0,0 +1,580 @@
+using Test
+using Sbplib.LazyTensors
+using Sbplib.RegionIndices
+
+using Tullio
+
+@testset "LazyTensors" begin
+
+@testset "Generic Mapping methods" begin
+    struct DummyMapping{T,R,D} <: TensorMapping{T,R,D} end
+    LazyTensors.apply(m::DummyMapping{T,R,D}, v, I::Vararg{Any,R}) where {T,R,D} = :apply
+    @test range_dim(DummyMapping{Int,2,3}()) == 2
+    @test domain_dim(DummyMapping{Int,2,3}()) == 3
+    @test apply(DummyMapping{Int,2,3}(), zeros(Int, (0,0,0)),0,0) == :apply
+    @test eltype(DummyMapping{Int,2,3}()) == Int
+    @test eltype(DummyMapping{Float64,2,3}()) == Float64
+end
+
+@testset "Mapping transpose" begin
+    struct DummyMapping{T,R,D} <: TensorMapping{T,R,D} end
+
+    LazyTensors.apply(m::DummyMapping{T,R}, v, I::Vararg{Any,R}) where {T,R} = :apply
+    LazyTensors.apply_transpose(m::DummyMapping{T,R,D}, v, I::Vararg{Any,D}) where {T,R,D} = :apply_transpose
+
+    LazyTensors.range_size(m::DummyMapping) = :range_size
+    LazyTensors.domain_size(m::DummyMapping) = :domain_size
+
+    m = DummyMapping{Float64,2,3}()
+    @test m' isa TensorMapping{Float64, 3,2}
+    @test m'' == m
+    @test apply(m',zeros(Float64,(0,0)), 0, 0, 0) == :apply_transpose
+    @test apply(m'',zeros(Float64,(0,0,0)), 0, 0) == :apply
+    @test apply_transpose(m', zeros(Float64,(0,0,0)), 0, 0) == :apply
+
+    @test range_size(m') == :domain_size
+    @test domain_size(m') == :range_size
+end
+
+@testset "TensorApplication" begin
+    struct SizeDoublingMapping{T,R,D} <: TensorMapping{T,R,D}
+        domain_size::NTuple{D,Int}
+    end
+
+    LazyTensors.apply(m::SizeDoublingMapping{T,R}, v, i::Vararg{Any,R}) where {T,R} = (:apply,v,i)
+    LazyTensors.range_size(m::SizeDoublingMapping) = 2 .* m.domain_size
+    LazyTensors.domain_size(m::SizeDoublingMapping) = m.domain_size
+
+
+    m = SizeDoublingMapping{Int, 1, 1}((3,))
+    v = [0,1,2]
+    @test m*v isa AbstractVector{Int}
+    @test size(m*v) == 2 .*size(v)
+    @test (m*v)[0] == (:apply,v,(0,))
+    @test m*m*v isa AbstractVector{Int}
+    @test (m*m*v)[1] == (:apply,m*v,(1,))
+    @test (m*m*v)[3] == (:apply,m*v,(3,))
+    @test (m*m*v)[6] == (:apply,m*v,(6,))
+    @test_broken BoundsError == (m*m*v)[0]
+    @test_broken BoundsError == (m*m*v)[7]
+    @test_throws MethodError m*m
+
+    m = SizeDoublingMapping{Int, 2, 1}((3,))
+    @test_throws MethodError m*ones(Int,2,2)
+    @test_throws MethodError m*m*v
+
+    m = SizeDoublingMapping{Float64, 2, 2}((3,3))
+    v = ones(3,3)
+    @test size(m*v) == 2 .*size(v)
+    @test (m*v)[1,2] == (:apply,v,(1,2))
+
+    struct ScalingOperator{T,D} <: TensorMapping{T,D,D}
+        λ::T
+        size::NTuple{D,Int}
+    end
+
+    LazyTensors.apply(m::ScalingOperator{T,D}, v, I::Vararg{Any,D}) where {T,D} = m.λ*v[I...]
+    LazyTensors.range_size(m::ScalingOperator) = m.size
+    LazyTensors.domain_size(m::ScalingOperator) = m.size
+
+    m = ScalingOperator{Int,1}(2,(3,))
+    v = [1,2,3]
+    @test m*v isa AbstractVector
+    @test m*v == [2,4,6]
+
+    m = ScalingOperator{Int,2}(2,(2,2))
+    v = [[1 2];[3 4]]
+    @test m*v == [[2 4];[6 8]]
+    @test (m*v)[2,1] == 6
+end
+
+@testset "TensorMapping binary operations" begin
+    struct ScalarMapping{T,R,D} <: TensorMapping{T,R,D}
+        λ::T
+        range_size::NTuple{R,Int}
+        domain_size::NTuple{D,Int}
+    end
+
+    LazyTensors.apply(m::ScalarMapping{T,R}, v, I::Vararg{Any,R}) where {T,R} = m.λ*v[I...]
+    LazyTensors.range_size(m::ScalarMapping) = m.domain_size
+    LazyTensors.domain_size(m::ScalarMapping) = m.range_size
+
+    A = ScalarMapping{Float64,1,1}(2.0, (3,), (3,))
+    B = ScalarMapping{Float64,1,1}(3.0, (3,), (3,))
+
+    v = [1.1,1.2,1.3]
+    for i ∈ eachindex(v)
+        @test ((A+B)*v)[i] == 2*v[i] + 3*v[i]
+    end
+
+    for i ∈ eachindex(v)
+        @test ((A-B)*v)[i] == 2*v[i] - 3*v[i]
+    end
+
+    @test range_size(A+B) == range_size(A) == range_size(B)
+    @test domain_size(A+B) == domain_size(A) == domain_size(B)
+end
+
+@testset "LazyArray" begin
+    @testset "LazyConstantArray" begin
+        @test LazyTensors.LazyConstantArray(3,(3,2)) isa LazyArray{Int,2}
+
+        lca = LazyTensors.LazyConstantArray(3.0,(3,2))
+        @test eltype(lca) == Float64
+        @test ndims(lca) == 2
+        @test size(lca) == (3,2)
+        @test lca[2] == 3.0
+    end
+    struct DummyArray{T,D, T1<:AbstractArray{T,D}} <: LazyArray{T,D}
+        data::T1
+    end
+    Base.size(v::DummyArray) = size(v.data)
+    Base.getindex(v::DummyArray{T,D}, I::Vararg{Int,D}) where {T,D} = v.data[I...]
+
+    # Test lazy operations
+    v1 = [1, 2.3, 4]
+    v2 = [1., 2, 3]
+    s = 3.4
+    r_add_v = v1 .+ v2
+    r_sub_v = v1 .- v2
+    r_times_v = v1 .* v2
+    r_div_v = v1 ./ v2
+    r_add_s = v1 .+ s
+    r_sub_s = v1 .- s
+    r_times_s = v1 .* s
+    r_div_s = v1 ./ s
+    @test isa(v1 +̃ v2, LazyArray)
+    @test isa(v1 -̃ v2, LazyArray)
+    @test isa(v1 *̃ v2, LazyArray)
+    @test isa(v1 /̃ v2, LazyArray)
+    @test isa(v1 +̃ s, LazyArray)
+    @test isa(v1 -̃ s, LazyArray)
+    @test isa(v1 *̃ s, LazyArray)
+    @test isa(v1 /̃ s, LazyArray)
+    @test isa(s +̃ v1, LazyArray)
+    @test isa(s -̃ v1, LazyArray)
+    @test isa(s *̃ v1, LazyArray)
+    @test isa(s /̃ v1, LazyArray)
+    for i ∈ eachindex(v1)
+        @test (v1 +̃ v2)[i] == r_add_v[i]
+        @test (v1 -̃ v2)[i] == r_sub_v[i]
+        @test (v1 *̃ v2)[i] == r_times_v[i]
+        @test (v1 /̃ v2)[i] == r_div_v[i]
+        @test (v1 +̃ s)[i] == r_add_s[i]
+        @test (v1 -̃ s)[i] == r_sub_s[i]
+        @test (v1 *̃ s)[i] == r_times_s[i]
+        @test (v1 /̃ s)[i] == r_div_s[i]
+        @test (s +̃ v1)[i] == r_add_s[i]
+        @test (s -̃ v1)[i] == -r_sub_s[i]
+        @test (s *̃ v1)[i] == r_times_s[i]
+        @test (s /̃ v1)[i] == 1/r_div_s[i]
+    end
+    @test_throws BoundsError (v1 +̃  v2)[4]
+    v2 = [1., 2, 3, 4]
+    # Test that size of arrays is asserted when not specified inbounds
+    # TODO: Replace these errors with SizeMismatch
+    @test_throws DimensionMismatch v1 +̃ v2
+
+    # Test operations on LazyArray
+    v1 = DummyArray([1, 2.3, 4])
+    v2 = [1., 2, 3]
+    @test isa(v1 + v2, LazyArray)
+    @test isa(v2 + v1, LazyArray)
+    @test isa(v1 - v2, LazyArray)
+    @test isa(v2 - v1, LazyArray)
+    for i ∈ eachindex(v2)
+        @test (v1 + v2)[i] == (v2 + v1)[i] == r_add_v[i]
+        @test (v1 - v2)[i] == -(v2 - v1)[i] == r_sub_v[i]
+    end
+    @test_throws BoundsError (v1 + v2)[4]
+    v2 = [1., 2, 3, 4]
+    # Test that size of arrays is asserted when not specified inbounds
+    # TODO: Replace these errors with SizeMismatch
+    @test_throws DimensionMismatch v1 + v2
+end
+
+
+@testset "LazyFunctionArray" begin
+    @test LazyFunctionArray(i->i^2, (3,)) == [1,4,9]
+    @test LazyFunctionArray((i,j)->i*j, (3,2)) == [
+        1 2;
+        2 4;
+        3 6;
+    ]
+
+    @test size(LazyFunctionArray(i->i^2, (3,))) == (3,)
+    @test size(LazyFunctionArray((i,j)->i*j, (3,2))) == (3,2)
+
+    @inferred LazyFunctionArray(i->i^2, (3,))[2]
+
+    @test_throws BoundsError LazyFunctionArray(i->i^2, (3,))[4]
+    @test_throws BoundsError LazyFunctionArray((i,j)->i*j, (3,2))[4,2]
+    @test_throws BoundsError LazyFunctionArray((i,j)->i*j, (3,2))[2,3]
+
+end
+
+@testset "TensorMappingComposition" begin
+    A = rand(2,3)
+    B = rand(3,4)
+
+    Ã = LazyLinearMap(A, (1,), (2,))
+    B̃ = LazyLinearMap(B, (1,), (2,))
+
+    @test Ã∘B̃ isa TensorMappingComposition
+    @test range_size(Ã∘B̃) == (2,)
+    @test domain_size(Ã∘B̃) == (4,)
+    @test_throws SizeMismatch B̃∘Ã
+
+    # @test @inbounds B̃∘Ã # Should not error even though dimensions don't match. (Since ]test runs with forced boundschecking this is currently not testable 2020-10-16)
+
+    v = rand(4)
+    @test Ã∘B̃*v ≈ A*B*v rtol=1e-14
+
+    v = rand(2)
+    @test (Ã∘B̃)'*v ≈ B'*A'*v rtol=1e-14
+end
+
+@testset "LazyLinearMap" begin
+    # Test a standard matrix-vector product
+    # mapping vectors of size 4 to vectors of size 3.
+    A = rand(3,4)
+    Ã = LazyLinearMap(A, (1,), (2,))
+    v = rand(4)
+    w = rand(3)
+
+    @test à isa LazyLinearMap{T,1,1} where T
+    @test à isa TensorMapping{T,1,1} where T
+    @test range_size(Ã) == (3,)
+    @test domain_size(Ã) == (4,)
+
+    @test Ã*ones(4) ≈ A*ones(4) atol=5e-13
+    @test Ã*v ≈ A*v atol=5e-13
+    @test Ã'*w ≈ A'*w
+
+    A = rand(2,3,4)
+    @test_throws DomainError LazyLinearMap(A, (3,1), (2,))
+
+    # Test more exotic mappings
+    B = rand(3,4,2)
+    # Map vectors of size 2 to matrices of size (3,4)
+    B̃ = LazyLinearMap(B, (1,2), (3,))
+    v = rand(2)
+
+    @test range_size(B̃) == (3,4)
+    @test domain_size(B̃) == (2,)
+    @test B̃ isa TensorMapping{T,2,1} where T
+    @test B̃*ones(2) ≈ B[:,:,1] + B[:,:,2] atol=5e-13
+    @test B̃*v ≈ B[:,:,1]*v[1] + B[:,:,2]*v[2] atol=5e-13
+
+    # Map matrices of size (3,2) to vectors of size 4
+    B̃ = LazyLinearMap(B, (2,), (1,3))
+    v = rand(3,2)
+
+    @test range_size(B̃) == (4,)
+    @test domain_size(B̃) == (3,2)
+    @test B̃ isa TensorMapping{T,1,2} where T
+    @test B̃*ones(3,2) ≈ B[1,:,1] + B[2,:,1] + B[3,:,1] +
+                        B[1,:,2] + B[2,:,2] + B[3,:,2] atol=5e-13
+    @test B̃*v ≈ B[1,:,1]*v[1,1] + B[2,:,1]*v[2,1] + B[3,:,1]*v[3,1] +
+                B[1,:,2]v[1,2] + B[2,:,2]*v[2,2] + B[3,:,2]*v[3,2] atol=5e-13
+
+
+    # TODO:
+    # @inferred (B̃*v)[2]
+end
+
+
+@testset "IdentityMapping" begin
+    @test IdentityMapping{Float64}((4,5)) isa IdentityMapping{T,2} where T
+    @test IdentityMapping{Float64}((4,5)) isa TensorMapping{T,2,2} where T
+    @test IdentityMapping{Float64}((4,5)) == IdentityMapping{Float64}(4,5)
+
+    @test IdentityMapping(3,2) isa IdentityMapping{Float64,2}
+
+    for sz ∈ [(4,5),(3,),(5,6,4)]
+        I = IdentityMapping{Float64}(sz)
+        v = rand(sz...)
+        @test I*v == v
+        @test I'*v == v
+
+        @test range_size(I) == sz
+        @test domain_size(I) == sz
+    end
+
+    I = IdentityMapping{Float64}((4,5))
+    v = rand(4,5)
+    @inferred (I*v)[3,2]
+    @inferred (I'*v)[3,2]
+    @inferred range_size(I)
+
+    @inferred range_dim(I)
+    @inferred domain_dim(I)
+
+    Ã = rand(4,2)
+    A = LazyLinearMap(Ã,(1,),(2,))
+    I1 = IdentityMapping{Float64}(2)
+    I2 = IdentityMapping{Float64}(4)
+    @test A∘I1 == A
+    @test I2∘A == A
+    @test I1∘I1 == I1
+    @test_throws SizeMismatch I1∘A
+    @test_throws SizeMismatch A∘I2
+    @test_throws SizeMismatch I1∘I2
+end
+
+@testset "InflatedTensorMapping" begin
+    I(sz...) = IdentityMapping(sz...)
+
+    Ã = rand(4,2)
+    B̃ = rand(4,2,3)
+    C̃ = rand(4,2,3)
+
+    A = LazyLinearMap(Ã,(1,),(2,))
+    B = LazyLinearMap(B̃,(1,2),(3,))
+    C = LazyLinearMap(C̃,(1,),(2,3))
+
+    @testset "Constructors" begin
+        @test InflatedTensorMapping(I(3,2), A, I(4)) isa TensorMapping{Float64, 4, 4}
+        @test InflatedTensorMapping(I(3,2), B, I(4)) isa TensorMapping{Float64, 5, 4}
+        @test InflatedTensorMapping(I(3), C, I(2,3)) isa TensorMapping{Float64, 4, 5}
+        @test InflatedTensorMapping(C, I(2,3)) isa TensorMapping{Float64, 3, 4}
+        @test InflatedTensorMapping(I(3), C) isa TensorMapping{Float64, 2, 3}
+        @test InflatedTensorMapping(I(3), I(2,3)) isa TensorMapping{Float64, 3, 3}
+    end
+
+    @testset "Range and domain size" begin
+        @test range_size(InflatedTensorMapping(I(3,2), A, I(4))) == (3,2,4,4)
+        @test domain_size(InflatedTensorMapping(I(3,2), A, I(4))) == (3,2,2,4)
+
+        @test range_size(InflatedTensorMapping(I(3,2), B, I(4))) == (3,2,4,2,4)
+        @test domain_size(InflatedTensorMapping(I(3,2), B, I(4))) == (3,2,3,4)
+
+        @test range_size(InflatedTensorMapping(I(3), C, I(2,3))) == (3,4,2,3)
+        @test domain_size(InflatedTensorMapping(I(3), C, I(2,3))) == (3,2,3,2,3)
+
+        @inferred range_size(InflatedTensorMapping(I(3,2), A, I(4))) == (3,2,4,4)
+        @inferred domain_size(InflatedTensorMapping(I(3,2), A, I(4))) == (3,2,2,4)
+    end
+
+    @testset "Application" begin
+        # Testing regular application and transposed application with inflation "before", "after" and "before and after".
+        # The inflated tensor mappings are chosen to preserve, reduce and increase the dimension of the result compared to the input.
+        tests = [
+            (
+                InflatedTensorMapping(I(3,2), A, I(4)),
+                (v-> @tullio res[a,b,c,d] := Ã[c,i]*v[a,b,i,d]), # Expected result of apply
+                (v-> @tullio res[a,b,c,d] := Ã[i,c]*v[a,b,i,d]), # Expected result of apply_transpose
+            ),
+            (
+                InflatedTensorMapping(I(3,2), B, I(4)),
+                (v-> @tullio res[a,b,c,d,e] := B̃[c,d,i]*v[a,b,i,e]),
+                (v-> @tullio res[a,b,c,d] := B̃[i,j,c]*v[a,b,i,j,d]),
+            ),
+            (
+                InflatedTensorMapping(I(3,2), C, I(4)),
+                (v-> @tullio res[a,b,c,d] := C̃[c,i,j]*v[a,b,i,j,d]),
+                (v-> @tullio res[a,b,c,d,e] := C̃[i,c,d]*v[a,b,i,e]),
+            ),
+            (
+                InflatedTensorMapping(I(3,2), A),
+                (v-> @tullio res[a,b,c] := Ã[c,i]*v[a,b,i]),
+                (v-> @tullio res[a,b,c] := Ã[i,c]*v[a,b,i]),
+            ),
+            (
+                InflatedTensorMapping(I(3,2), B),
+                (v-> @tullio res[a,b,c,d] := B̃[c,d,i]*v[a,b,i]),
+                (v-> @tullio res[a,b,c] := B̃[i,j,c]*v[a,b,i,j]),
+            ),
+            (
+                InflatedTensorMapping(I(3,2), C),
+                (v-> @tullio res[a,b,c] := C̃[c,i,j]*v[a,b,i,j]),
+                (v-> @tullio res[a,b,c,d] := C̃[i,c,d]*v[a,b,i]),
+            ),
+            (
+                InflatedTensorMapping(A,I(4)),
+                (v-> @tullio res[a,b] := Ã[a,i]*v[i,b]),
+                (v-> @tullio res[a,b] := Ã[i,a]*v[i,b]),
+            ),
+            (
+                InflatedTensorMapping(B,I(4)),
+                (v-> @tullio res[a,b,c] := B̃[a,b,i]*v[i,c]),
+                (v-> @tullio res[a,b] := B̃[i,j,a]*v[i,j,b]),
+            ),
+            (
+                InflatedTensorMapping(C,I(4)),
+                (v-> @tullio res[a,b] := C̃[a,i,j]*v[i,j,b]),
+                (v-> @tullio res[a,b,c] := C̃[i,a,b]*v[i,c]),
+            ),
+        ]
+
+        @testset "apply" begin
+            for i ∈ 1:length(tests)
+                tm = tests[i][1]
+                v = rand(domain_size(tm)...)
+                true_value = tests[i][2](v)
+                @test tm*v ≈ true_value rtol=1e-14
+            end
+        end
+
+        @testset "apply_transpose" begin
+            for i ∈ 1:length(tests)
+                tm = tests[i][1]
+                v = rand(range_size(tm)...)
+                true_value = tests[i][3](v)
+                @test tm'*v ≈ true_value rtol=1e-14
+            end
+        end
+
+        @testset "Inference of application" begin
+            struct ScalingOperator{T,D} <: TensorMapping{T,D,D}
+                λ::T
+                size::NTuple{D,Int}
+            end
+
+            LazyTensors.apply(m::ScalingOperator{T,D}, v, I::Vararg{Any,D}) where {T,D} = m.λ*v[I...]
+            LazyTensors.range_size(m::ScalingOperator) = m.size
+            LazyTensors.domain_size(m::ScalingOperator) = m.size
+
+            tm = InflatedTensorMapping(I(2,3),ScalingOperator(2.0, (3,2)),I(3,4))
+            v = rand(domain_size(tm)...)
+
+            @inferred apply(tm,v,1,2,3,2,2,4)
+            @inferred (tm*v)[1,2,3,2,2,4]
+        end
+    end
+
+    @testset "InflatedTensorMapping of InflatedTensorMapping" begin
+        A = ScalingOperator(2.0,(2,3))
+        itm = InflatedTensorMapping(I(3,2), A, I(4))
+        @test  InflatedTensorMapping(I(4), itm, I(2)) == InflatedTensorMapping(I(4,3,2), A, I(4,2))
+        @test  InflatedTensorMapping(itm, I(2)) == InflatedTensorMapping(I(3,2), A, I(4,2))
+        @test  InflatedTensorMapping(I(4), itm) == InflatedTensorMapping(I(4,3,2), A, I(4))
+
+        @test InflatedTensorMapping(I(2), I(2), I(2)) isa InflatedTensorMapping # The constructor should always return its type.
+    end
+end
+
+@testset "split_index" begin
+    @test LazyTensors.split_index(Val(2),Val(1),Val(2),Val(2),1,2,3,4,5,6) == ((1,2,:,5,6),(3,4))
+    @test LazyTensors.split_index(Val(2),Val(3),Val(2),Val(2),1,2,3,4,5,6) == ((1,2,:,:,:,5,6),(3,4))
+    @test LazyTensors.split_index(Val(3),Val(1),Val(1),Val(2),1,2,3,4,5,6) == ((1,2,3,:,5,6),(4,))
+    @test LazyTensors.split_index(Val(3),Val(2),Val(1),Val(2),1,2,3,4,5,6) == ((1,2,3,:,:,5,6),(4,))
+    @test LazyTensors.split_index(Val(1),Val(1),Val(2),Val(3),1,2,3,4,5,6) == ((1,:,4,5,6),(2,3))
+    @test LazyTensors.split_index(Val(1),Val(2),Val(2),Val(3),1,2,3,4,5,6) == ((1,:,:,4,5,6),(2,3))
+
+    @test LazyTensors.split_index(Val(0),Val(1),Val(3),Val(3),1,2,3,4,5,6) == ((:,4,5,6),(1,2,3))
+    @test LazyTensors.split_index(Val(3),Val(1),Val(3),Val(0),1,2,3,4,5,6) == ((1,2,3,:),(4,5,6))
+
+    @inferred LazyTensors.split_index(Val(2),Val(3),Val(2),Val(2),1,2,3,2,2,4)
+end
+
+@testset "slice_tuple" begin
+    @test LazyTensors.slice_tuple((1,2,3),Val(1), Val(3)) == (1,2,3)
+    @test LazyTensors.slice_tuple((1,2,3,4,5,6),Val(2), Val(5)) == (2,3,4,5)
+    @test LazyTensors.slice_tuple((1,2,3,4,5,6),Val(1), Val(3)) == (1,2,3)
+    @test LazyTensors.slice_tuple((1,2,3,4,5,6),Val(4), Val(6)) == (4,5,6)
+end
+
+@testset "split_tuple" begin
+    @testset "2 parts" begin
+        @test LazyTensors.split_tuple((),Val(0)) == ((),())
+        @test LazyTensors.split_tuple((1,),Val(0)) == ((),(1,))
+        @test LazyTensors.split_tuple((1,),Val(1)) == ((1,),())
+
+        @test LazyTensors.split_tuple((1,2,3,4),Val(0)) == ((),(1,2,3,4))
+        @test LazyTensors.split_tuple((1,2,3,4),Val(1)) == ((1,),(2,3,4))
+        @test LazyTensors.split_tuple((1,2,3,4),Val(2)) == ((1,2),(3,4))
+        @test LazyTensors.split_tuple((1,2,3,4),Val(3)) == ((1,2,3),(4,))
+        @test LazyTensors.split_tuple((1,2,3,4),Val(4)) == ((1,2,3,4),())
+
+        @test LazyTensors.split_tuple((1,2,true,4),Val(3)) == ((1,2,true),(4,))
+
+        @inferred LazyTensors.split_tuple((1,2,3,4),Val(3))
+        @inferred LazyTensors.split_tuple((1,2,true,4),Val(3))
+    end
+
+    @testset "3 parts" begin
+        @test LazyTensors.split_tuple((),Val(0),Val(0)) == ((),(),())
+        @test LazyTensors.split_tuple((1,2,3),Val(1), Val(1)) == ((1,),(2,),(3,))
+        @test LazyTensors.split_tuple((1,true,3),Val(1), Val(1)) == ((1,),(true,),(3,))
+
+        @test LazyTensors.split_tuple((1,2,3,4,5,6),Val(1),Val(2)) == ((1,),(2,3),(4,5,6))
+        @test LazyTensors.split_tuple((1,2,3,4,5,6),Val(3),Val(2)) == ((1,2,3),(4,5),(6,))
+
+        @inferred LazyTensors.split_tuple((1,2,3,4,5,6),Val(3),Val(2))
+        @inferred LazyTensors.split_tuple((1,true,3),Val(1), Val(1))
+    end
+end
+
+@testset "flatten_tuple" begin
+    @test LazyTensors.flatten_tuple((1,)) == (1,)
+    @test LazyTensors.flatten_tuple((1,2,3,4,5,6)) == (1,2,3,4,5,6)
+    @test LazyTensors.flatten_tuple((1,2,(3,4),5,6)) == (1,2,3,4,5,6)
+    @test LazyTensors.flatten_tuple((1,2,(3,(4,5)),6)) == (1,2,3,4,5,6)
+    @test LazyTensors.flatten_tuple(((1,2),(3,4),(5,),6)) == (1,2,3,4,5,6)
+end
+
+
+@testset "LazyOuterProduct" begin
+    struct ScalingOperator{T,D} <: TensorMapping{T,D,D}
+        λ::T
+        size::NTuple{D,Int}
+    end
+
+    LazyTensors.apply(m::ScalingOperator{T,D}, v, I::Vararg{Any,D}) where {T,D} = m.λ*v[I...]
+    LazyTensors.range_size(m::ScalingOperator) = m.size
+    LazyTensors.domain_size(m::ScalingOperator) = m.size
+
+    A = ScalingOperator(2.0, (5,))
+    B = ScalingOperator(3.0, (3,))
+    C = ScalingOperator(5.0, (3,2))
+
+    AB = LazyOuterProduct(A,B)
+    @test AB isa TensorMapping{T,2,2} where T
+    @test range_size(AB) == (5,3)
+    @test domain_size(AB) == (5,3)
+
+    v = rand(range_size(AB)...)
+    @test AB*v == 6*v
+
+    ABC = LazyOuterProduct(A,B,C)
+
+    @test ABC isa TensorMapping{T,4,4} where T
+    @test range_size(ABC) == (5,3,3,2)
+    @test domain_size(ABC) == (5,3,3,2)
+
+    @test A⊗B == AB
+    @test A⊗B⊗C == ABC
+
+    A = rand(3,2)
+    B = rand(2,4,3)
+
+    v₁ = rand(2,4,3)
+    v₂ = rand(4,3,2)
+
+    Ã = LazyLinearMap(A,(1,),(2,))
+    B̃ = LazyLinearMap(B,(1,),(2,3))
+
+    ÃB̃ = LazyOuterProduct(Ã,B̃)
+    @tullio ABv[i,k] := A[i,j]*B[k,l,m]*v₁[j,l,m]
+    @test ÃB̃*v₁ ≈ ABv
+
+    B̃Ã = LazyOuterProduct(B̃,Ã)
+    @tullio BAv[k,i] := A[i,j]*B[k,l,m]*v₂[l,m,j]
+    @test B̃Ã*v₂ ≈ BAv
+
+    @testset "Indentity mapping arguments" begin
+        @test LazyOuterProduct(IdentityMapping(3,2), IdentityMapping(1,2)) == IdentityMapping(3,2,1,2)
+
+        Ã = LazyLinearMap(A,(1,),(2,))
+        @test LazyOuterProduct(IdentityMapping(3,2), Ã) == InflatedTensorMapping(IdentityMapping(3,2),Ã)
+        @test LazyOuterProduct(Ã, IdentityMapping(3,2)) == InflatedTensorMapping(Ã,IdentityMapping(3,2))
+
+        I1 = IdentityMapping(3,2)
+        I2 = IdentityMapping(4)
+        @test I1⊗Ã⊗I2 == InflatedTensorMapping(I1, Ã, I2)
+    end
+
+end
+
+end
--- a/test/LazyTensors/testLazyTensors.jl	Sat Feb 20 20:36:27 2021 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,580 +0,0 @@
-using Test
-using Sbplib.LazyTensors
-using Sbplib.RegionIndices
-
-using Tullio
-
-@testset "LazyTensors" begin
-
-@testset "Generic Mapping methods" begin
-    struct DummyMapping{T,R,D} <: TensorMapping{T,R,D} end
-    LazyTensors.apply(m::DummyMapping{T,R,D}, v, I::Vararg{Any,R}) where {T,R,D} = :apply
-    @test range_dim(DummyMapping{Int,2,3}()) == 2
-    @test domain_dim(DummyMapping{Int,2,3}()) == 3
-    @test apply(DummyMapping{Int,2,3}(), zeros(Int, (0,0,0)),0,0) == :apply
-    @test eltype(DummyMapping{Int,2,3}()) == Int
-    @test eltype(DummyMapping{Float64,2,3}()) == Float64
-end
-
-@testset "Mapping transpose" begin
-    struct DummyMapping{T,R,D} <: TensorMapping{T,R,D} end
-
-    LazyTensors.apply(m::DummyMapping{T,R}, v, I::Vararg{Any,R}) where {T,R} = :apply
-    LazyTensors.apply_transpose(m::DummyMapping{T,R,D}, v, I::Vararg{Any,D}) where {T,R,D} = :apply_transpose
-
-    LazyTensors.range_size(m::DummyMapping) = :range_size
-    LazyTensors.domain_size(m::DummyMapping) = :domain_size
-
-    m = DummyMapping{Float64,2,3}()
-    @test m' isa TensorMapping{Float64, 3,2}
-    @test m'' == m
-    @test apply(m',zeros(Float64,(0,0)), 0, 0, 0) == :apply_transpose
-    @test apply(m'',zeros(Float64,(0,0,0)), 0, 0) == :apply
-    @test apply_transpose(m', zeros(Float64,(0,0,0)), 0, 0) == :apply
-
-    @test range_size(m') == :domain_size
-    @test domain_size(m') == :range_size
-end
-
-@testset "TensorApplication" begin
-    struct SizeDoublingMapping{T,R,D} <: TensorMapping{T,R,D}
-        domain_size::NTuple{D,Int}
-    end
-
-    LazyTensors.apply(m::SizeDoublingMapping{T,R}, v, i::Vararg{Any,R}) where {T,R} = (:apply,v,i)
-    LazyTensors.range_size(m::SizeDoublingMapping) = 2 .* m.domain_size
-    LazyTensors.domain_size(m::SizeDoublingMapping) = m.domain_size
-
-
-    m = SizeDoublingMapping{Int, 1, 1}((3,))
-    v = [0,1,2]
-    @test m*v isa AbstractVector{Int}
-    @test size(m*v) == 2 .*size(v)
-    @test (m*v)[0] == (:apply,v,(0,))
-    @test m*m*v isa AbstractVector{Int}
-    @test (m*m*v)[1] == (:apply,m*v,(1,))
-    @test (m*m*v)[3] == (:apply,m*v,(3,))
-    @test (m*m*v)[6] == (:apply,m*v,(6,))
-    @test_broken BoundsError == (m*m*v)[0]
-    @test_broken BoundsError == (m*m*v)[7]
-    @test_throws MethodError m*m
-
-    m = SizeDoublingMapping{Int, 2, 1}((3,))
-    @test_throws MethodError m*ones(Int,2,2)
-    @test_throws MethodError m*m*v
-
-    m = SizeDoublingMapping{Float64, 2, 2}((3,3))
-    v = ones(3,3)
-    @test size(m*v) == 2 .*size(v)
-    @test (m*v)[1,2] == (:apply,v,(1,2))
-
-    struct ScalingOperator{T,D} <: TensorMapping{T,D,D}
-        λ::T
-        size::NTuple{D,Int}
-    end
-
-    LazyTensors.apply(m::ScalingOperator{T,D}, v, I::Vararg{Any,D}) where {T,D} = m.λ*v[I...]
-    LazyTensors.range_size(m::ScalingOperator) = m.size
-    LazyTensors.domain_size(m::ScalingOperator) = m.size
-
-    m = ScalingOperator{Int,1}(2,(3,))
-    v = [1,2,3]
-    @test m*v isa AbstractVector
-    @test m*v == [2,4,6]
-
-    m = ScalingOperator{Int,2}(2,(2,2))
-    v = [[1 2];[3 4]]
-    @test m*v == [[2 4];[6 8]]
-    @test (m*v)[2,1] == 6
-end
-
-@testset "TensorMapping binary operations" begin
-    struct ScalarMapping{T,R,D} <: TensorMapping{T,R,D}
-        λ::T
-        range_size::NTuple{R,Int}
-        domain_size::NTuple{D,Int}
-    end
-
-    LazyTensors.apply(m::ScalarMapping{T,R}, v, I::Vararg{Any,R}) where {T,R} = m.λ*v[I...]
-    LazyTensors.range_size(m::ScalarMapping) = m.domain_size
-    LazyTensors.domain_size(m::ScalarMapping) = m.range_size
-
-    A = ScalarMapping{Float64,1,1}(2.0, (3,), (3,))
-    B = ScalarMapping{Float64,1,1}(3.0, (3,), (3,))
-
-    v = [1.1,1.2,1.3]
-    for i ∈ eachindex(v)
-        @test ((A+B)*v)[i] == 2*v[i] + 3*v[i]
-    end
-
-    for i ∈ eachindex(v)
-        @test ((A-B)*v)[i] == 2*v[i] - 3*v[i]
-    end
-
-    @test range_size(A+B) == range_size(A) == range_size(B)
-    @test domain_size(A+B) == domain_size(A) == domain_size(B)
-end
-
-@testset "LazyArray" begin
-    @testset "LazyConstantArray" begin
-        @test LazyTensors.LazyConstantArray(3,(3,2)) isa LazyArray{Int,2}
-
-        lca = LazyTensors.LazyConstantArray(3.0,(3,2))
-        @test eltype(lca) == Float64
-        @test ndims(lca) == 2
-        @test size(lca) == (3,2)
-        @test lca[2] == 3.0
-    end
-    struct DummyArray{T,D, T1<:AbstractArray{T,D}} <: LazyArray{T,D}
-        data::T1
-    end
-    Base.size(v::DummyArray) = size(v.data)
-    Base.getindex(v::DummyArray{T,D}, I::Vararg{Int,D}) where {T,D} = v.data[I...]
-
-    # Test lazy operations
-    v1 = [1, 2.3, 4]
-    v2 = [1., 2, 3]
-    s = 3.4
-    r_add_v = v1 .+ v2
-    r_sub_v = v1 .- v2
-    r_times_v = v1 .* v2
-    r_div_v = v1 ./ v2
-    r_add_s = v1 .+ s
-    r_sub_s = v1 .- s
-    r_times_s = v1 .* s
-    r_div_s = v1 ./ s
-    @test isa(v1 +̃ v2, LazyArray)
-    @test isa(v1 -̃ v2, LazyArray)
-    @test isa(v1 *̃ v2, LazyArray)
-    @test isa(v1 /̃ v2, LazyArray)
-    @test isa(v1 +̃ s, LazyArray)
-    @test isa(v1 -̃ s, LazyArray)
-    @test isa(v1 *̃ s, LazyArray)
-    @test isa(v1 /̃ s, LazyArray)
-    @test isa(s +̃ v1, LazyArray)
-    @test isa(s -̃ v1, LazyArray)
-    @test isa(s *̃ v1, LazyArray)
-    @test isa(s /̃ v1, LazyArray)
-    for i ∈ eachindex(v1)
-        @test (v1 +̃ v2)[i] == r_add_v[i]
-        @test (v1 -̃ v2)[i] == r_sub_v[i]
-        @test (v1 *̃ v2)[i] == r_times_v[i]
-        @test (v1 /̃ v2)[i] == r_div_v[i]
-        @test (v1 +̃ s)[i] == r_add_s[i]
-        @test (v1 -̃ s)[i] == r_sub_s[i]
-        @test (v1 *̃ s)[i] == r_times_s[i]
-        @test (v1 /̃ s)[i] == r_div_s[i]
-        @test (s +̃ v1)[i] == r_add_s[i]
-        @test (s -̃ v1)[i] == -r_sub_s[i]
-        @test (s *̃ v1)[i] == r_times_s[i]
-        @test (s /̃ v1)[i] == 1/r_div_s[i]
-    end
-    @test_throws BoundsError (v1 +̃  v2)[4]
-    v2 = [1., 2, 3, 4]
-    # Test that size of arrays is asserted when not specified inbounds
-    # TODO: Replace these errors with SizeMismatch
-    @test_throws DimensionMismatch v1 +̃ v2
-
-    # Test operations on LazyArray
-    v1 = DummyArray([1, 2.3, 4])
-    v2 = [1., 2, 3]
-    @test isa(v1 + v2, LazyArray)
-    @test isa(v2 + v1, LazyArray)
-    @test isa(v1 - v2, LazyArray)
-    @test isa(v2 - v1, LazyArray)
-    for i ∈ eachindex(v2)
-        @test (v1 + v2)[i] == (v2 + v1)[i] == r_add_v[i]
-        @test (v1 - v2)[i] == -(v2 - v1)[i] == r_sub_v[i]
-    end
-    @test_throws BoundsError (v1 + v2)[4]
-    v2 = [1., 2, 3, 4]
-    # Test that size of arrays is asserted when not specified inbounds
-    # TODO: Replace these errors with SizeMismatch
-    @test_throws DimensionMismatch v1 + v2
-end
-
-
-@testset "LazyFunctionArray" begin
-    @test LazyFunctionArray(i->i^2, (3,)) == [1,4,9]
-    @test LazyFunctionArray((i,j)->i*j, (3,2)) == [
-        1 2;
-        2 4;
-        3 6;
-    ]
-
-    @test size(LazyFunctionArray(i->i^2, (3,))) == (3,)
-    @test size(LazyFunctionArray((i,j)->i*j, (3,2))) == (3,2)
-
-    @inferred LazyFunctionArray(i->i^2, (3,))[2]
-
-    @test_throws BoundsError LazyFunctionArray(i->i^2, (3,))[4]
-    @test_throws BoundsError LazyFunctionArray((i,j)->i*j, (3,2))[4,2]
-    @test_throws BoundsError LazyFunctionArray((i,j)->i*j, (3,2))[2,3]
-
-end
-
-@testset "TensorMappingComposition" begin
-    A = rand(2,3)
-    B = rand(3,4)
-
-    Ã = LazyLinearMap(A, (1,), (2,))
-    B̃ = LazyLinearMap(B, (1,), (2,))
-
-    @test Ã∘B̃ isa TensorMappingComposition
-    @test range_size(Ã∘B̃) == (2,)
-    @test domain_size(Ã∘B̃) == (4,)
-    @test_throws SizeMismatch B̃∘Ã
-
-    # @test @inbounds B̃∘Ã # Should not error even though dimensions don't match. (Since ]test runs with forced boundschecking this is currently not testable 2020-10-16)
-
-    v = rand(4)
-    @test Ã∘B̃*v ≈ A*B*v rtol=1e-14
-
-    v = rand(2)
-    @test (Ã∘B̃)'*v ≈ B'*A'*v rtol=1e-14
-end
-
-@testset "LazyLinearMap" begin
-    # Test a standard matrix-vector product
-    # mapping vectors of size 4 to vectors of size 3.
-    A = rand(3,4)
-    Ã = LazyLinearMap(A, (1,), (2,))
-    v = rand(4)
-    w = rand(3)
-
-    @test à isa LazyLinearMap{T,1,1} where T
-    @test à isa TensorMapping{T,1,1} where T
-    @test range_size(Ã) == (3,)
-    @test domain_size(Ã) == (4,)
-
-    @test Ã*ones(4) ≈ A*ones(4) atol=5e-13
-    @test Ã*v ≈ A*v atol=5e-13
-    @test Ã'*w ≈ A'*w
-
-    A = rand(2,3,4)
-    @test_throws DomainError LazyLinearMap(A, (3,1), (2,))
-
-    # Test more exotic mappings
-    B = rand(3,4,2)
-    # Map vectors of size 2 to matrices of size (3,4)
-    B̃ = LazyLinearMap(B, (1,2), (3,))
-    v = rand(2)
-
-    @test range_size(B̃) == (3,4)
-    @test domain_size(B̃) == (2,)
-    @test B̃ isa TensorMapping{T,2,1} where T
-    @test B̃*ones(2) ≈ B[:,:,1] + B[:,:,2] atol=5e-13
-    @test B̃*v ≈ B[:,:,1]*v[1] + B[:,:,2]*v[2] atol=5e-13
-
-    # Map matrices of size (3,2) to vectors of size 4
-    B̃ = LazyLinearMap(B, (2,), (1,3))
-    v = rand(3,2)
-
-    @test range_size(B̃) == (4,)
-    @test domain_size(B̃) == (3,2)
-    @test B̃ isa TensorMapping{T,1,2} where T
-    @test B̃*ones(3,2) ≈ B[1,:,1] + B[2,:,1] + B[3,:,1] +
-                        B[1,:,2] + B[2,:,2] + B[3,:,2] atol=5e-13
-    @test B̃*v ≈ B[1,:,1]*v[1,1] + B[2,:,1]*v[2,1] + B[3,:,1]*v[3,1] +
-                B[1,:,2]v[1,2] + B[2,:,2]*v[2,2] + B[3,:,2]*v[3,2] atol=5e-13
-
-
-    # TODO:
-    # @inferred (B̃*v)[2]
-end
-
-
-@testset "IdentityMapping" begin
-    @test IdentityMapping{Float64}((4,5)) isa IdentityMapping{T,2} where T
-    @test IdentityMapping{Float64}((4,5)) isa TensorMapping{T,2,2} where T
-    @test IdentityMapping{Float64}((4,5)) == IdentityMapping{Float64}(4,5)
-
-    @test IdentityMapping(3,2) isa IdentityMapping{Float64,2}
-
-    for sz ∈ [(4,5),(3,),(5,6,4)]
-        I = IdentityMapping{Float64}(sz)
-        v = rand(sz...)
-        @test I*v == v
-        @test I'*v == v
-
-        @test range_size(I) == sz
-        @test domain_size(I) == sz
-    end
-
-    I = IdentityMapping{Float64}((4,5))
-    v = rand(4,5)
-    @inferred (I*v)[3,2]
-    @inferred (I'*v)[3,2]
-    @inferred range_size(I)
-
-    @inferred range_dim(I)
-    @inferred domain_dim(I)
-
-    Ã = rand(4,2)
-    A = LazyLinearMap(Ã,(1,),(2,))
-    I1 = IdentityMapping{Float64}(2)
-    I2 = IdentityMapping{Float64}(4)
-    @test A∘I1 == A
-    @test I2∘A == A
-    @test I1∘I1 == I1
-    @test_throws SizeMismatch I1∘A
-    @test_throws SizeMismatch A∘I2
-    @test_throws SizeMismatch I1∘I2
-end
-
-@testset "InflatedTensorMapping" begin
-    I(sz...) = IdentityMapping(sz...)
-
-    Ã = rand(4,2)
-    B̃ = rand(4,2,3)
-    C̃ = rand(4,2,3)
-
-    A = LazyLinearMap(Ã,(1,),(2,))
-    B = LazyLinearMap(B̃,(1,2),(3,))
-    C = LazyLinearMap(C̃,(1,),(2,3))
-
-    @testset "Constructors" begin
-        @test InflatedTensorMapping(I(3,2), A, I(4)) isa TensorMapping{Float64, 4, 4}
-        @test InflatedTensorMapping(I(3,2), B, I(4)) isa TensorMapping{Float64, 5, 4}
-        @test InflatedTensorMapping(I(3), C, I(2,3)) isa TensorMapping{Float64, 4, 5}
-        @test InflatedTensorMapping(C, I(2,3)) isa TensorMapping{Float64, 3, 4}
-        @test InflatedTensorMapping(I(3), C) isa TensorMapping{Float64, 2, 3}
-        @test InflatedTensorMapping(I(3), I(2,3)) isa TensorMapping{Float64, 3, 3}
-    end
-
-    @testset "Range and domain size" begin
-        @test range_size(InflatedTensorMapping(I(3,2), A, I(4))) == (3,2,4,4)
-        @test domain_size(InflatedTensorMapping(I(3,2), A, I(4))) == (3,2,2,4)
-
-        @test range_size(InflatedTensorMapping(I(3,2), B, I(4))) == (3,2,4,2,4)
-        @test domain_size(InflatedTensorMapping(I(3,2), B, I(4))) == (3,2,3,4)
-
-        @test range_size(InflatedTensorMapping(I(3), C, I(2,3))) == (3,4,2,3)
-        @test domain_size(InflatedTensorMapping(I(3), C, I(2,3))) == (3,2,3,2,3)
-
-        @inferred range_size(InflatedTensorMapping(I(3,2), A, I(4))) == (3,2,4,4)
-        @inferred domain_size(InflatedTensorMapping(I(3,2), A, I(4))) == (3,2,2,4)
-    end
-
-    @testset "Application" begin
-        # Testing regular application and transposed application with inflation "before", "after" and "before and after".
-        # The inflated tensor mappings are chosen to preserve, reduce and increase the dimension of the result compared to the input.
-        tests = [
-            (
-                InflatedTensorMapping(I(3,2), A, I(4)),
-                (v-> @tullio res[a,b,c,d] := Ã[c,i]*v[a,b,i,d]), # Expected result of apply
-                (v-> @tullio res[a,b,c,d] := Ã[i,c]*v[a,b,i,d]), # Expected result of apply_transpose
-            ),
-            (
-                InflatedTensorMapping(I(3,2), B, I(4)),
-                (v-> @tullio res[a,b,c,d,e] := B̃[c,d,i]*v[a,b,i,e]),
-                (v-> @tullio res[a,b,c,d] := B̃[i,j,c]*v[a,b,i,j,d]),
-            ),
-            (
-                InflatedTensorMapping(I(3,2), C, I(4)),
-                (v-> @tullio res[a,b,c,d] := C̃[c,i,j]*v[a,b,i,j,d]),
-                (v-> @tullio res[a,b,c,d,e] := C̃[i,c,d]*v[a,b,i,e]),
-            ),
-            (
-                InflatedTensorMapping(I(3,2), A),
-                (v-> @tullio res[a,b,c] := Ã[c,i]*v[a,b,i]),
-                (v-> @tullio res[a,b,c] := Ã[i,c]*v[a,b,i]),
-            ),
-            (
-                InflatedTensorMapping(I(3,2), B),
-                (v-> @tullio res[a,b,c,d] := B̃[c,d,i]*v[a,b,i]),
-                (v-> @tullio res[a,b,c] := B̃[i,j,c]*v[a,b,i,j]),
-            ),
-            (
-                InflatedTensorMapping(I(3,2), C),
-                (v-> @tullio res[a,b,c] := C̃[c,i,j]*v[a,b,i,j]),
-                (v-> @tullio res[a,b,c,d] := C̃[i,c,d]*v[a,b,i]),
-            ),
-            (
-                InflatedTensorMapping(A,I(4)),
-                (v-> @tullio res[a,b] := Ã[a,i]*v[i,b]),
-                (v-> @tullio res[a,b] := Ã[i,a]*v[i,b]),
-            ),
-            (
-                InflatedTensorMapping(B,I(4)),
-                (v-> @tullio res[a,b,c] := B̃[a,b,i]*v[i,c]),
-                (v-> @tullio res[a,b] := B̃[i,j,a]*v[i,j,b]),
-            ),
-            (
-                InflatedTensorMapping(C,I(4)),
-                (v-> @tullio res[a,b] := C̃[a,i,j]*v[i,j,b]),
-                (v-> @tullio res[a,b,c] := C̃[i,a,b]*v[i,c]),
-            ),
-        ]
-
-        @testset "apply" begin
-            for i ∈ 1:length(tests)
-                tm = tests[i][1]
-                v = rand(domain_size(tm)...)
-                true_value = tests[i][2](v)
-                @test tm*v ≈ true_value rtol=1e-14
-            end
-        end
-
-        @testset "apply_transpose" begin
-            for i ∈ 1:length(tests)
-                tm = tests[i][1]
-                v = rand(range_size(tm)...)
-                true_value = tests[i][3](v)
-                @test tm'*v ≈ true_value rtol=1e-14
-            end
-        end
-
-        @testset "Inference of application" begin
-            struct ScalingOperator{T,D} <: TensorMapping{T,D,D}
-                λ::T
-                size::NTuple{D,Int}
-            end
-
-            LazyTensors.apply(m::ScalingOperator{T,D}, v, I::Vararg{Any,D}) where {T,D} = m.λ*v[I...]
-            LazyTensors.range_size(m::ScalingOperator) = m.size
-            LazyTensors.domain_size(m::ScalingOperator) = m.size
-
-            tm = InflatedTensorMapping(I(2,3),ScalingOperator(2.0, (3,2)),I(3,4))
-            v = rand(domain_size(tm)...)
-
-            @inferred apply(tm,v,1,2,3,2,2,4)
-            @inferred (tm*v)[1,2,3,2,2,4]
-        end
-    end
-
-    @testset "InflatedTensorMapping of InflatedTensorMapping" begin
-        A = ScalingOperator(2.0,(2,3))
-        itm = InflatedTensorMapping(I(3,2), A, I(4))
-        @test  InflatedTensorMapping(I(4), itm, I(2)) == InflatedTensorMapping(I(4,3,2), A, I(4,2))
-        @test  InflatedTensorMapping(itm, I(2)) == InflatedTensorMapping(I(3,2), A, I(4,2))
-        @test  InflatedTensorMapping(I(4), itm) == InflatedTensorMapping(I(4,3,2), A, I(4))
-
-        @test InflatedTensorMapping(I(2), I(2), I(2)) isa InflatedTensorMapping # The constructor should always return its type.
-    end
-end
-
-@testset "split_index" begin
-    @test LazyTensors.split_index(Val(2),Val(1),Val(2),Val(2),1,2,3,4,5,6) == ((1,2,:,5,6),(3,4))
-    @test LazyTensors.split_index(Val(2),Val(3),Val(2),Val(2),1,2,3,4,5,6) == ((1,2,:,:,:,5,6),(3,4))
-    @test LazyTensors.split_index(Val(3),Val(1),Val(1),Val(2),1,2,3,4,5,6) == ((1,2,3,:,5,6),(4,))
-    @test LazyTensors.split_index(Val(3),Val(2),Val(1),Val(2),1,2,3,4,5,6) == ((1,2,3,:,:,5,6),(4,))
-    @test LazyTensors.split_index(Val(1),Val(1),Val(2),Val(3),1,2,3,4,5,6) == ((1,:,4,5,6),(2,3))
-    @test LazyTensors.split_index(Val(1),Val(2),Val(2),Val(3),1,2,3,4,5,6) == ((1,:,:,4,5,6),(2,3))
-
-    @test LazyTensors.split_index(Val(0),Val(1),Val(3),Val(3),1,2,3,4,5,6) == ((:,4,5,6),(1,2,3))
-    @test LazyTensors.split_index(Val(3),Val(1),Val(3),Val(0),1,2,3,4,5,6) == ((1,2,3,:),(4,5,6))
-
-    @inferred LazyTensors.split_index(Val(2),Val(3),Val(2),Val(2),1,2,3,2,2,4)
-end
-
-@testset "slice_tuple" begin
-    @test LazyTensors.slice_tuple((1,2,3),Val(1), Val(3)) == (1,2,3)
-    @test LazyTensors.slice_tuple((1,2,3,4,5,6),Val(2), Val(5)) == (2,3,4,5)
-    @test LazyTensors.slice_tuple((1,2,3,4,5,6),Val(1), Val(3)) == (1,2,3)
-    @test LazyTensors.slice_tuple((1,2,3,4,5,6),Val(4), Val(6)) == (4,5,6)
-end
-
-@testset "split_tuple" begin
-    @testset "2 parts" begin
-        @test LazyTensors.split_tuple((),Val(0)) == ((),())
-        @test LazyTensors.split_tuple((1,),Val(0)) == ((),(1,))
-        @test LazyTensors.split_tuple((1,),Val(1)) == ((1,),())
-
-        @test LazyTensors.split_tuple((1,2,3,4),Val(0)) == ((),(1,2,3,4))
-        @test LazyTensors.split_tuple((1,2,3,4),Val(1)) == ((1,),(2,3,4))
-        @test LazyTensors.split_tuple((1,2,3,4),Val(2)) == ((1,2),(3,4))
-        @test LazyTensors.split_tuple((1,2,3,4),Val(3)) == ((1,2,3),(4,))
-        @test LazyTensors.split_tuple((1,2,3,4),Val(4)) == ((1,2,3,4),())
-
-        @test LazyTensors.split_tuple((1,2,true,4),Val(3)) == ((1,2,true),(4,))
-
-        @inferred LazyTensors.split_tuple((1,2,3,4),Val(3))
-        @inferred LazyTensors.split_tuple((1,2,true,4),Val(3))
-    end
-
-    @testset "3 parts" begin
-        @test LazyTensors.split_tuple((),Val(0),Val(0)) == ((),(),())
-        @test LazyTensors.split_tuple((1,2,3),Val(1), Val(1)) == ((1,),(2,),(3,))
-        @test LazyTensors.split_tuple((1,true,3),Val(1), Val(1)) == ((1,),(true,),(3,))
-
-        @test LazyTensors.split_tuple((1,2,3,4,5,6),Val(1),Val(2)) == ((1,),(2,3),(4,5,6))
-        @test LazyTensors.split_tuple((1,2,3,4,5,6),Val(3),Val(2)) == ((1,2,3),(4,5),(6,))
-
-        @inferred LazyTensors.split_tuple((1,2,3,4,5,6),Val(3),Val(2))
-        @inferred LazyTensors.split_tuple((1,true,3),Val(1), Val(1))
-    end
-end
-
-@testset "flatten_tuple" begin
-    @test LazyTensors.flatten_tuple((1,)) == (1,)
-    @test LazyTensors.flatten_tuple((1,2,3,4,5,6)) == (1,2,3,4,5,6)
-    @test LazyTensors.flatten_tuple((1,2,(3,4),5,6)) == (1,2,3,4,5,6)
-    @test LazyTensors.flatten_tuple((1,2,(3,(4,5)),6)) == (1,2,3,4,5,6)
-    @test LazyTensors.flatten_tuple(((1,2),(3,4),(5,),6)) == (1,2,3,4,5,6)
-end
-
-
-@testset "LazyOuterProduct" begin
-    struct ScalingOperator{T,D} <: TensorMapping{T,D,D}
-        λ::T
-        size::NTuple{D,Int}
-    end
-
-    LazyTensors.apply(m::ScalingOperator{T,D}, v, I::Vararg{Any,D}) where {T,D} = m.λ*v[I...]
-    LazyTensors.range_size(m::ScalingOperator) = m.size
-    LazyTensors.domain_size(m::ScalingOperator) = m.size
-
-    A = ScalingOperator(2.0, (5,))
-    B = ScalingOperator(3.0, (3,))
-    C = ScalingOperator(5.0, (3,2))
-
-    AB = LazyOuterProduct(A,B)
-    @test AB isa TensorMapping{T,2,2} where T
-    @test range_size(AB) == (5,3)
-    @test domain_size(AB) == (5,3)
-
-    v = rand(range_size(AB)...)
-    @test AB*v == 6*v
-
-    ABC = LazyOuterProduct(A,B,C)
-
-    @test ABC isa TensorMapping{T,4,4} where T
-    @test range_size(ABC) == (5,3,3,2)
-    @test domain_size(ABC) == (5,3,3,2)
-
-    @test A⊗B == AB
-    @test A⊗B⊗C == ABC
-
-    A = rand(3,2)
-    B = rand(2,4,3)
-
-    v₁ = rand(2,4,3)
-    v₂ = rand(4,3,2)
-
-    Ã = LazyLinearMap(A,(1,),(2,))
-    B̃ = LazyLinearMap(B,(1,),(2,3))
-
-    ÃB̃ = LazyOuterProduct(Ã,B̃)
-    @tullio ABv[i,k] := A[i,j]*B[k,l,m]*v₁[j,l,m]
-    @test ÃB̃*v₁ ≈ ABv
-
-    B̃Ã = LazyOuterProduct(B̃,Ã)
-    @tullio BAv[k,i] := A[i,j]*B[k,l,m]*v₂[l,m,j]
-    @test B̃Ã*v₂ ≈ BAv
-
-    @testset "Indentity mapping arguments" begin
-        @test LazyOuterProduct(IdentityMapping(3,2), IdentityMapping(1,2)) == IdentityMapping(3,2,1,2)
-
-        Ã = LazyLinearMap(A,(1,),(2,))
-        @test LazyOuterProduct(IdentityMapping(3,2), Ã) == InflatedTensorMapping(IdentityMapping(3,2),Ã)
-        @test LazyOuterProduct(Ã, IdentityMapping(3,2)) == InflatedTensorMapping(Ã,IdentityMapping(3,2))
-
-        I1 = IdentityMapping(3,2)
-        I2 = IdentityMapping(4)
-        @test I1⊗Ã⊗I2 == InflatedTensorMapping(I1, Ã, I2)
-    end
-
-end
-
-end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/RegionIndices/RegionIndices_test.jl	Sat Feb 20 20:45:40 2021 +0100
@@ -0,0 +1,6 @@
+using Sbplib.RegionIndices
+using Test
+
+@testset "RegionIndices" begin
+	@test_broken false
+end
--- a/test/RegionIndices/testRegionIndices.jl	Sat Feb 20 20:36:27 2021 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,6 +0,0 @@
-using Sbplib.RegionIndices
-using Test
-
-@testset "RegionIndices" begin
-	@test_broken false
-end
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/SbpOperators/SbpOperators_test.jl	Sat Feb 20 20:45:40 2021 +0100
@@ -0,0 +1,832 @@
+using Test
+using Sbplib.SbpOperators
+using Sbplib.Grids
+using Sbplib.RegionIndices
+using Sbplib.LazyTensors
+using LinearAlgebra
+using TOML
+
+import Sbplib.SbpOperators.Stencil
+import Sbplib.SbpOperators.VolumeOperator
+import Sbplib.SbpOperators.volume_operator
+import Sbplib.SbpOperators.BoundaryOperator
+import Sbplib.SbpOperators.boundary_operator
+import Sbplib.SbpOperators.even
+import Sbplib.SbpOperators.odd
+
+
+@testset "SbpOperators" begin
+
+@testset "Stencil" begin
+    s = Stencil((-2,2), (1.,2.,2.,3.,4.))
+    @test s isa Stencil{Float64, 5}
+
+    @test eltype(s) == Float64
+    @test SbpOperators.scale(s, 2) == Stencil((-2,2), (2.,4.,4.,6.,8.))
+
+    @test Stencil(1,2,3,4; center=1) == Stencil((0, 3),(1,2,3,4))
+    @test Stencil(1,2,3,4; center=2) == Stencil((-1, 2),(1,2,3,4))
+    @test Stencil(1,2,3,4; center=4) == Stencil((-3, 0),(1,2,3,4))
+
+    @test CenteredStencil(1,2,3,4,5) == Stencil((-2, 2), (1,2,3,4,5))
+    @test_throws ArgumentError CenteredStencil(1,2,3,4)
+end
+
+@testset "parse_rational" begin
+    @test SbpOperators.parse_rational("1") isa Rational
+    @test SbpOperators.parse_rational("1") == 1//1
+    @test SbpOperators.parse_rational("1/2") isa Rational
+    @test SbpOperators.parse_rational("1/2") == 1//2
+    @test SbpOperators.parse_rational("37/13") isa Rational
+    @test SbpOperators.parse_rational("37/13") == 37//13
+end
+
+@testset "readoperator" begin
+    toml_str = """
+        [meta]
+        type = "equidistant"
+
+        [order2]
+        H.inner = ["1"]
+
+        D1.inner_stencil = ["-1/2", "0", "1/2"]
+        D1.closure_stencils = [
+            ["-1", "1"],
+        ]
+
+        d1.closure = ["-3/2", "2", "-1/2"]
+
+        [order4]
+        H.closure = ["17/48", "59/48", "43/48", "49/48"]
+
+        D2.inner_stencil = ["-1/12","4/3","-5/2","4/3","-1/12"]
+        D2.closure_stencils = [
+            [     "2",    "-5",      "4",       "-1",     "0",     "0"],
+            [     "1",    "-2",      "1",        "0",     "0",     "0"],
+            [ "-4/43", "59/43", "-110/43",   "59/43", "-4/43",     "0"],
+            [ "-1/49",     "0",   "59/49", "-118/49", "64/49", "-4/49"],
+        ]
+    """
+
+    parsed_toml = TOML.parse(toml_str)
+    @testset "get_stencil" begin
+        @test get_stencil(parsed_toml, "order2", "D1", "inner_stencil") == Stencil(-1/2, 0., 1/2, center=2)
+        @test get_stencil(parsed_toml, "order2", "D1", "inner_stencil", center=1) == Stencil(-1/2, 0., 1/2; center=1)
+        @test get_stencil(parsed_toml, "order2", "D1", "inner_stencil", center=3) == Stencil(-1/2, 0., 1/2; center=3)
+
+        @test get_stencil(parsed_toml, "order2", "H", "inner") == Stencil(1.; center=1)
+
+        @test_throws AssertionError get_stencil(parsed_toml, "meta", "type")
+        @test_throws AssertionError get_stencil(parsed_toml, "order2", "D1", "closure_stencils")
+    end
+
+    @testset "get_stencils" begin
+        @test get_stencils(parsed_toml, "order2", "D1", "closure_stencils", centers=(1,)) == (Stencil(-1., 1., center=1),)
+        @test get_stencils(parsed_toml, "order2", "D1", "closure_stencils", centers=(2,)) == (Stencil(-1., 1., center=2),)
+        @test get_stencils(parsed_toml, "order2", "D1", "closure_stencils", centers=[2]) == (Stencil(-1., 1., center=2),)
+
+        @test get_stencils(parsed_toml, "order4", "D2", "closure_stencils",centers=[1,1,1,1]) == (
+            Stencil(    2.,    -5.,      4.,     -1.,    0.,    0., center=1),
+            Stencil(    1.,    -2.,      1.,      0.,    0.,    0., center=1),
+            Stencil( -4/43,  59/43, -110/43,   59/43, -4/43,    0., center=1),
+            Stencil( -1/49,     0.,   59/49, -118/49, 64/49, -4/49, center=1),
+        )
+
+        @test get_stencils(parsed_toml, "order4", "D2", "closure_stencils",centers=(4,2,3,1)) == (
+            Stencil(    2.,    -5.,      4.,     -1.,    0.,    0., center=4),
+            Stencil(    1.,    -2.,      1.,      0.,    0.,    0., center=2),
+            Stencil( -4/43,  59/43, -110/43,   59/43, -4/43,    0., center=3),
+            Stencil( -1/49,     0.,   59/49, -118/49, 64/49, -4/49, center=1),
+        )
+
+        @test get_stencils(parsed_toml, "order4", "D2", "closure_stencils",centers=1:4) == (
+            Stencil(    2.,    -5.,      4.,     -1.,    0.,    0., center=1),
+            Stencil(    1.,    -2.,      1.,      0.,    0.,    0., center=2),
+            Stencil( -4/43,  59/43, -110/43,   59/43, -4/43,    0., center=3),
+            Stencil( -1/49,     0.,   59/49, -118/49, 64/49, -4/49, center=4),
+        )
+
+        @test_throws AssertionError get_stencils(parsed_toml, "order4", "D2", "closure_stencils",centers=(1,2,3))
+        @test_throws AssertionError get_stencils(parsed_toml, "order4", "D2", "closure_stencils",centers=(1,2,3,5,4))
+        @test_throws AssertionError get_stencils(parsed_toml, "order4", "D2", "inner_stencil",centers=(1,2))
+    end
+
+    @testset "get_tuple" begin
+        @test get_tuple(parsed_toml, "order2", "d1", "closure") == (-3/2, 2, -1/2)
+
+        @test_throws AssertionError get_tuple(parsed_toml, "meta", "type")
+    end
+end
+
+@testset "VolumeOperator" begin
+    inner_stencil = CenteredStencil(1/4, 2/4, 1/4)
+    closure_stencils = (Stencil(1/2, 1/2; center=1), Stencil(0.,1.; center=2))
+    g_1D = EquidistantGrid(11,0.,1.)
+    g_2D = EquidistantGrid((11,12),(0.,0.),(1.,1.))
+    g_3D = EquidistantGrid((11,12,10),(0.,0.,0.),(1.,1.,1.))
+    @testset "Constructors" begin
+        @testset "1D" begin
+            op = VolumeOperator(inner_stencil,closure_stencils,(11,),even)
+            @test op == VolumeOperator(g_1D,inner_stencil,closure_stencils,even)
+            @test op == volume_operator(g_1D,inner_stencil,closure_stencils,even,1)
+            @test op isa TensorMapping{T,1,1} where T
+        end
+        @testset "2D" begin
+            op_x = volume_operator(g_2D,inner_stencil,closure_stencils,even,1)
+            op_y = volume_operator(g_2D,inner_stencil,closure_stencils,even,2)
+            Ix = IdentityMapping{Float64}((11,))
+            Iy = IdentityMapping{Float64}((12,))
+            @test op_x == VolumeOperator(inner_stencil,closure_stencils,(11,),even)⊗Iy
+            @test op_y == Ix⊗VolumeOperator(inner_stencil,closure_stencils,(12,),even)
+            @test op_x isa TensorMapping{T,2,2} where T
+            @test op_y isa TensorMapping{T,2,2} where T
+        end
+        @testset "3D" begin
+            op_x = volume_operator(g_3D,inner_stencil,closure_stencils,even,1)
+            op_y = volume_operator(g_3D,inner_stencil,closure_stencils,even,2)
+            op_z = volume_operator(g_3D,inner_stencil,closure_stencils,even,3)
+            Ix = IdentityMapping{Float64}((11,))
+            Iy = IdentityMapping{Float64}((12,))
+            Iz = IdentityMapping{Float64}((10,))
+            @test op_x == VolumeOperator(inner_stencil,closure_stencils,(11,),even)⊗Iy⊗Iz
+            @test op_y == Ix⊗VolumeOperator(inner_stencil,closure_stencils,(12,),even)⊗Iz
+            @test op_z == Ix⊗Iy⊗VolumeOperator(inner_stencil,closure_stencils,(10,),even)
+            @test op_x isa TensorMapping{T,3,3} where T
+            @test op_y isa TensorMapping{T,3,3} where T
+            @test op_z isa TensorMapping{T,3,3} where T
+        end
+    end
+
+    @testset "Sizes" begin
+        @testset "1D" begin
+            op = volume_operator(g_1D,inner_stencil,closure_stencils,even,1)
+            @test range_size(op) == domain_size(op) == size(g_1D)
+        end
+
+        @testset "2D" begin
+            op_x = volume_operator(g_2D,inner_stencil,closure_stencils,even,1)
+            op_y = volume_operator(g_2D,inner_stencil,closure_stencils,even,2)
+            @test range_size(op_y) == domain_size(op_y) ==
+                  range_size(op_x) == domain_size(op_x) == size(g_2D)
+        end
+        @testset "3D" begin
+            op_x = volume_operator(g_3D,inner_stencil,closure_stencils,even,1)
+            op_y = volume_operator(g_3D,inner_stencil,closure_stencils,even,2)
+            op_z = volume_operator(g_3D,inner_stencil,closure_stencils,even,3)
+            @test range_size(op_z) == domain_size(op_z) ==
+                  range_size(op_y) == domain_size(op_y) ==
+                  range_size(op_x) == domain_size(op_x) == size(g_3D)
+        end
+    end
+
+    op_x = volume_operator(g_2D,inner_stencil,closure_stencils,even,1)
+    op_y = volume_operator(g_2D,inner_stencil,closure_stencils,odd,2)
+    v = zeros(size(g_2D))
+    Nx = size(g_2D)[1]
+    Ny = size(g_2D)[2]
+    for i = 1:Nx
+        v[i,:] .= i
+    end
+    rx = copy(v)
+    rx[1,:] .= 1.5
+    rx[Nx,:] .= (2*Nx-1)/2
+    ry = copy(v)
+    ry[:,Ny-1:Ny] = -v[:,Ny-1:Ny]
+
+    @testset "Application" begin
+        @test op_x*v ≈ rx rtol = 1e-14
+        @test op_y*v ≈ ry rtol = 1e-14
+    end
+
+    @testset "Regions" begin
+        @test (op_x*v)[Index(1,Lower),Index(3,Interior)] ≈ rx[1,3] rtol = 1e-14
+        @test (op_x*v)[Index(2,Lower),Index(3,Interior)] ≈ rx[2,3] rtol = 1e-14
+        @test (op_x*v)[Index(6,Interior),Index(3,Interior)] ≈ rx[6,3] rtol = 1e-14
+        @test (op_x*v)[Index(10,Upper),Index(3,Interior)] ≈ rx[10,3] rtol = 1e-14
+        @test (op_x*v)[Index(11,Upper),Index(3,Interior)] ≈ rx[11,3] rtol = 1e-14
+
+        @test_throws BoundsError (op_x*v)[Index(3,Lower),Index(3,Interior)]
+        @test_throws BoundsError (op_x*v)[Index(9,Upper),Index(3,Interior)]
+
+        @test (op_y*v)[Index(3,Interior),Index(1,Lower)] ≈ ry[3,1] rtol = 1e-14
+        @test (op_y*v)[Index(3,Interior),Index(2,Lower)] ≈ ry[3,2] rtol = 1e-14
+        @test (op_y*v)[Index(3,Interior),Index(6,Interior)] ≈ ry[3,6] rtol = 1e-14
+        @test (op_y*v)[Index(3,Interior),Index(11,Upper)] ≈ ry[3,11] rtol = 1e-14
+        @test (op_y*v)[Index(3,Interior),Index(12,Upper)] ≈ ry[3,12] rtol = 1e-14
+
+        @test_throws BoundsError (op_y*v)[Index(3,Interior),Index(10,Upper)]
+        @test_throws BoundsError (op_y*v)[Index(3,Interior),Index(3,Lower)]
+    end
+
+    @testset "Inferred" begin
+        @inferred apply(op_x, v,1,1)
+        @inferred apply(op_x, v, Index(1,Lower),Index(1,Lower))
+        @inferred apply(op_x, v, Index(6,Interior),Index(1,Lower))
+        @inferred apply(op_x, v, Index(11,Upper),Index(1,Lower))
+
+        @inferred apply(op_y, v,1,1)
+        @inferred apply(op_y, v, Index(1,Lower),Index(1,Lower))
+        @inferred apply(op_y, v, Index(1,Lower),Index(6,Interior))
+        @inferred apply(op_y, v, Index(1,Lower),Index(11,Upper))
+    end
+
+end
+
+@testset "SecondDerivative" begin
+    op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+    Lx = 3.5
+    Ly = 3.
+    g_1D = EquidistantGrid(121, 0.0, Lx)
+    g_2D = EquidistantGrid((121,123), (0.0, 0.0), (Lx, Ly))
+
+    @testset "Constructors" begin
+        @testset "1D" begin
+            Dₓₓ = second_derivative(g_1D,op.innerStencil,op.closureStencils)
+            @test Dₓₓ == second_derivative(g_1D,op.innerStencil,op.closureStencils,1)
+            @test Dₓₓ isa VolumeOperator
+        end
+        @testset "2D" begin
+            Dₓₓ = second_derivative(g_2D,op.innerStencil,op.closureStencils,1)
+            D2 = second_derivative(g_1D,op.innerStencil,op.closureStencils)
+            I = IdentityMapping{Float64}(size(g_2D)[2])
+            @test Dₓₓ == D2⊗I
+            @test Dₓₓ isa TensorMapping{T,2,2} where T
+        end
+    end
+
+    # Exact differentiation is measured point-wise. In other cases
+    # the error is measured in the l2-norm.
+    @testset "Accuracy" begin
+        @testset "1D" begin
+            l2(v) = sqrt(spacing(g_1D)[1]*sum(v.^2));
+            monomials = ()
+            maxOrder = 4;
+            for i = 0:maxOrder-1
+                f_i(x) = 1/factorial(i)*x^i
+                monomials = (monomials...,evalOn(g_1D,f_i))
+            end
+            v = evalOn(g_1D,x -> sin(x))
+            vₓₓ = evalOn(g_1D,x -> -sin(x))
+
+            # 2nd order interior stencil, 1nd order boundary stencil,
+            # implies that L*v should be exact for monomials up to order 2.
+            @testset "2nd order" begin
+                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=2)
+                Dₓₓ = second_derivative(g_1D,op.innerStencil,op.closureStencils)
+                @test Dₓₓ*monomials[1] ≈ zeros(Float64,size(g_1D)...) atol = 5e-10
+                @test Dₓₓ*monomials[2] ≈ zeros(Float64,size(g_1D)...) atol = 5e-10
+                @test Dₓₓ*monomials[3] ≈ monomials[1] atol = 5e-10
+                @test Dₓₓ*v ≈ vₓₓ rtol = 5e-2 norm = l2
+            end
+
+            # 4th order interior stencil, 2nd order boundary stencil,
+            # implies that L*v should be exact for monomials up to order 3.
+            @testset "4th order" begin
+                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+                Dₓₓ = second_derivative(g_1D,op.innerStencil,op.closureStencils)
+                # NOTE: high tolerances for checking the "exact" differentiation
+                # due to accumulation of round-off errors/cancellation errors?
+                @test Dₓₓ*monomials[1] ≈ zeros(Float64,size(g_1D)...) atol = 5e-10
+                @test Dₓₓ*monomials[2] ≈ zeros(Float64,size(g_1D)...) atol = 5e-10
+                @test Dₓₓ*monomials[3] ≈ monomials[1] atol = 5e-10
+                @test Dₓₓ*monomials[4] ≈ monomials[2] atol = 5e-10
+                @test Dₓₓ*v ≈ vₓₓ rtol = 5e-4 norm = l2
+            end
+        end
+
+        @testset "2D" begin
+            l2(v) = sqrt(prod(spacing(g_2D))*sum(v.^2));
+            binomials = ()
+            maxOrder = 4;
+            for i = 0:maxOrder-1
+                f_i(x,y) = 1/factorial(i)*y^i + x^i
+                binomials = (binomials...,evalOn(g_2D,f_i))
+            end
+            v = evalOn(g_2D, (x,y) -> sin(x)+cos(y))
+            v_yy = evalOn(g_2D,(x,y) -> -cos(y))
+
+            # 2nd order interior stencil, 1st order boundary stencil,
+            # implies that L*v should be exact for binomials up to order 2.
+            @testset "2nd order" begin
+                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=2)
+                Dyy = second_derivative(g_2D,op.innerStencil,op.closureStencils,2)
+                @test Dyy*binomials[1] ≈ zeros(Float64,size(g_2D)...) atol = 5e-9
+                @test Dyy*binomials[2] ≈ zeros(Float64,size(g_2D)...) atol = 5e-9
+                @test Dyy*binomials[3] ≈ evalOn(g_2D,(x,y)->1.) atol = 5e-9
+                @test Dyy*v ≈ v_yy rtol = 5e-2 norm = l2
+            end
+
+            # 4th order interior stencil, 2nd order boundary stencil,
+            # implies that L*v should be exact for binomials up to order 3.
+            @testset "4th order" begin
+                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+                Dyy = second_derivative(g_2D,op.innerStencil,op.closureStencils,2)
+                # NOTE: high tolerances for checking the "exact" differentiation
+                # due to accumulation of round-off errors/cancellation errors?
+                @test Dyy*binomials[1] ≈ zeros(Float64,size(g_2D)...) atol = 5e-9
+                @test Dyy*binomials[2] ≈ zeros(Float64,size(g_2D)...) atol = 5e-9
+                @test Dyy*binomials[3] ≈ evalOn(g_2D,(x,y)->1.) atol = 5e-9
+                @test Dyy*binomials[4] ≈ evalOn(g_2D,(x,y)->y) atol = 5e-9
+                @test Dyy*v ≈ v_yy rtol = 5e-4 norm = l2
+            end
+        end
+    end
+end
+
+@testset "Laplace" begin
+    g_1D = EquidistantGrid(101, 0.0, 1.)
+    g_3D = EquidistantGrid((51,101,52), (0.0, -1.0, 0.0), (1., 1., 1.))
+    @testset "Constructors" begin
+        op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+        @testset "1D" begin
+            L = laplace(g_1D, op.innerStencil, op.closureStencils)
+            @test L == second_derivative(g_1D, op.innerStencil, op.closureStencils)
+            @test L isa TensorMapping{T,1,1}  where T
+        end
+        @testset "3D" begin
+            L = laplace(g_3D, op.innerStencil, op.closureStencils)
+            @test L isa TensorMapping{T,3,3} where T
+            Dxx = second_derivative(g_3D, op.innerStencil, op.closureStencils,1)
+            Dyy = second_derivative(g_3D, op.innerStencil, op.closureStencils,2)
+            Dzz = second_derivative(g_3D, op.innerStencil, op.closureStencils,3)
+            @test L == Dxx + Dyy + Dzz
+        end
+    end
+
+    # Exact differentiation is measured point-wise. In other cases
+    # the error is measured in the l2-norm.
+    @testset "Accuracy" begin
+        l2(v) = sqrt(prod(spacing(g_3D))*sum(v.^2));
+        polynomials = ()
+        maxOrder = 4;
+        for i = 0:maxOrder-1
+            f_i(x,y,z) = 1/factorial(i)*(y^i + x^i + z^i)
+            polynomials = (polynomials...,evalOn(g_3D,f_i))
+        end
+        v = evalOn(g_3D, (x,y,z) -> sin(x) + cos(y) + exp(z))
+        Δv = evalOn(g_3D,(x,y,z) -> -sin(x) - cos(y) + exp(z))
+
+        # 2nd order interior stencil, 1st order boundary stencil,
+        # implies that L*v should be exact for binomials up to order 2.
+        @testset "2nd order" begin
+            op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=2)
+            L = laplace(g_3D,op.innerStencil,op.closureStencils)
+            @test L*polynomials[1] ≈ zeros(Float64, size(g_3D)...) atol = 5e-9
+            @test L*polynomials[2] ≈ zeros(Float64, size(g_3D)...) atol = 5e-9
+            @test L*polynomials[3] ≈ polynomials[1] atol = 5e-9
+            @test L*v ≈ Δv rtol = 5e-2 norm = l2
+        end
+
+        # 4th order interior stencil, 2nd order boundary stencil,
+        # implies that L*v should be exact for binomials up to order 3.
+        @testset "4th order" begin
+            op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+            L = laplace(g_3D,op.innerStencil,op.closureStencils)
+            # NOTE: high tolerances for checking the "exact" differentiation
+            # due to accumulation of round-off errors/cancellation errors?
+            @test L*polynomials[1] ≈ zeros(Float64, size(g_3D)...) atol = 5e-9
+            @test L*polynomials[2] ≈ zeros(Float64, size(g_3D)...) atol = 5e-9
+            @test L*polynomials[3] ≈ polynomials[1] atol = 5e-9
+            @test L*polynomials[4] ≈ polynomials[2] atol = 5e-9
+            @test L*v ≈ Δv rtol = 5e-4 norm = l2
+        end
+    end
+end
+
+@testset "Diagonal-stencil inner_product" begin
+    Lx = π/2.
+    Ly = Float64(π)
+    Lz = 1.
+    g_1D = EquidistantGrid(77, 0.0, Lx)
+    g_2D = EquidistantGrid((77,66), (0.0, 0.0), (Lx,Ly))
+    g_3D = EquidistantGrid((10,10, 10), (0.0, 0.0, 0.0), (Lx,Ly,Lz))
+    integral(H,v) = sum(H*v)
+    @testset "inner_product" begin
+        op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+        @testset "0D" begin
+            H = inner_product(EquidistantGrid{Float64}(),op.quadratureClosure)
+            @test H == IdentityMapping{Float64}()
+            @test H isa TensorMapping{T,0,0} where T
+        end
+        @testset "1D" begin
+            H = inner_product(g_1D,op.quadratureClosure)
+            inner_stencil = CenteredStencil(1.)
+            @test H == inner_product(g_1D,op.quadratureClosure,inner_stencil)
+            @test H isa TensorMapping{T,1,1} where T
+        end
+        @testset "2D" begin
+            H = inner_product(g_2D,op.quadratureClosure)
+            H_x = inner_product(restrict(g_2D,1),op.quadratureClosure)
+            H_y = inner_product(restrict(g_2D,2),op.quadratureClosure)
+            @test H == H_x⊗H_y
+            @test H isa TensorMapping{T,2,2} where T
+        end
+    end
+
+    @testset "Sizes" begin
+        op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+        @testset "1D" begin
+            H = inner_product(g_1D,op.quadratureClosure)
+            @test domain_size(H) == size(g_1D)
+            @test range_size(H) == size(g_1D)
+        end
+        @testset "2D" begin
+            H = inner_product(g_2D,op.quadratureClosure)
+            @test domain_size(H) == size(g_2D)
+            @test range_size(H) == size(g_2D)
+        end
+    end
+
+    @testset "Accuracy" begin
+        @testset "1D" begin
+            v = ()
+            for i = 0:4
+                f_i(x) = 1/factorial(i)*x^i
+                v = (v...,evalOn(g_1D,f_i))
+            end
+            u = evalOn(g_1D,x->sin(x))
+
+            @testset "2nd order" begin
+                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=2)
+                H = inner_product(g_1D,op.quadratureClosure)
+                for i = 1:2
+                    @test integral(H,v[i]) ≈ v[i+1][end] - v[i+1][1] rtol = 1e-14
+                end
+                @test integral(H,u) ≈ 1. rtol = 1e-4
+            end
+
+            @testset "4th order" begin
+                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+                H = inner_product(g_1D,op.quadratureClosure)
+                for i = 1:4
+                    @test integral(H,v[i]) ≈ v[i+1][end] -  v[i+1][1] rtol = 1e-14
+                end
+                @test integral(H,u) ≈ 1. rtol = 1e-8
+            end
+        end
+
+        @testset "2D" begin
+            b = 2.1
+            v = b*ones(Float64, size(g_2D))
+            u = evalOn(g_2D,(x,y)->sin(x)+cos(y))
+            @testset "2nd order" begin
+                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=2)
+                H = inner_product(g_2D,op.quadratureClosure)
+                @test integral(H,v) ≈ b*Lx*Ly rtol = 1e-13
+                @test integral(H,u) ≈ π rtol = 1e-4
+            end
+            @testset "4th order" begin
+                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+                H = inner_product(g_2D,op.quadratureClosure)
+                @test integral(H,v) ≈ b*Lx*Ly rtol = 1e-13
+                @test integral(H,u) ≈ π rtol = 1e-8
+            end
+        end
+    end
+end
+
+@testset "Diagonal-stencil inverse_inner_product" begin
+    Lx = π/2.
+    Ly = Float64(π)
+    g_1D = EquidistantGrid(77, 0.0, Lx)
+    g_2D = EquidistantGrid((77,66), (0.0, 0.0), (Lx,Ly))
+    @testset "inverse_inner_product" begin
+        op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+        @testset "0D" begin
+            Hi = inverse_inner_product(EquidistantGrid{Float64}(),op.quadratureClosure)
+            @test Hi == IdentityMapping{Float64}()
+            @test Hi isa TensorMapping{T,0,0} where T
+        end
+        @testset "1D" begin
+            Hi = inverse_inner_product(g_1D, op.quadratureClosure);
+            inner_stencil = CenteredStencil(1.)
+            closures = ()
+            for i = 1:length(op.quadratureClosure)
+                closures = (closures...,Stencil(op.quadratureClosure[i].range,1.0./op.quadratureClosure[i].weights))
+            end
+            @test Hi == inverse_inner_product(g_1D,closures,inner_stencil)
+            @test Hi isa TensorMapping{T,1,1} where T
+        end
+        @testset "2D" begin
+            Hi = inverse_inner_product(g_2D,op.quadratureClosure)
+            Hi_x = inverse_inner_product(restrict(g_2D,1),op.quadratureClosure)
+            Hi_y = inverse_inner_product(restrict(g_2D,2),op.quadratureClosure)
+            @test Hi == Hi_x⊗Hi_y
+            @test Hi isa TensorMapping{T,2,2} where T
+        end
+    end
+
+    @testset "Sizes" begin
+        op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+        @testset "1D" begin
+            Hi = inverse_inner_product(g_1D,op.quadratureClosure)
+            @test domain_size(Hi) == size(g_1D)
+            @test range_size(Hi) == size(g_1D)
+        end
+        @testset "2D" begin
+            Hi = inverse_inner_product(g_2D,op.quadratureClosure)
+            @test domain_size(Hi) == size(g_2D)
+            @test range_size(Hi) == size(g_2D)
+        end
+    end
+
+    @testset "Accuracy" begin
+        @testset "1D" begin
+            v = evalOn(g_1D,x->sin(x))
+            u = evalOn(g_1D,x->x^3-x^2+1)
+            @testset "2nd order" begin
+                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=2)
+                H = inner_product(g_1D,op.quadratureClosure)
+                Hi = inverse_inner_product(g_1D,op.quadratureClosure)
+                @test Hi*H*v ≈ v rtol = 1e-15
+                @test Hi*H*u ≈ u rtol = 1e-15
+            end
+            @testset "4th order" begin
+                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+                H = inner_product(g_1D,op.quadratureClosure)
+                Hi = inverse_inner_product(g_1D,op.quadratureClosure)
+                @test Hi*H*v ≈ v rtol = 1e-15
+                @test Hi*H*u ≈ u rtol = 1e-15
+            end
+        end
+        @testset "2D" begin
+            v = evalOn(g_2D,(x,y)->sin(x)+cos(y))
+            u = evalOn(g_2D,(x,y)->x*y + x^5 - sqrt(y))
+            @testset "2nd order" begin
+                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=2)
+                H = inner_product(g_2D,op.quadratureClosure)
+                Hi = inverse_inner_product(g_2D,op.quadratureClosure)
+                @test Hi*H*v ≈ v rtol = 1e-15
+                @test Hi*H*u ≈ u rtol = 1e-15
+            end
+            @testset "4th order" begin
+                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+                H = inner_product(g_2D,op.quadratureClosure)
+                Hi = inverse_inner_product(g_2D,op.quadratureClosure)
+                @test Hi*H*v ≈ v rtol = 1e-15
+                @test Hi*H*u ≈ u rtol = 1e-15
+            end
+        end
+    end
+end
+
+@testset "BoundaryOperator" begin
+    closure_stencil = Stencil((0,2), (2.,1.,3.))
+    g_1D = EquidistantGrid(11, 0.0, 1.0)
+    g_2D = EquidistantGrid((11,15), (0.0, 0.0), (1.0,1.0))
+
+    @testset "Constructors" begin
+        @testset "1D" begin
+            op_l = BoundaryOperator{Lower}(closure_stencil,size(g_1D)[1])
+            @test op_l == BoundaryOperator(g_1D,closure_stencil,Lower())
+            @test op_l == boundary_operator(g_1D,closure_stencil,CartesianBoundary{1,Lower}())
+            @test op_l isa TensorMapping{T,0,1} where T
+
+            op_r = BoundaryOperator{Upper}(closure_stencil,size(g_1D)[1])
+            @test op_r == BoundaryOperator(g_1D,closure_stencil,Upper())
+            @test op_r == boundary_operator(g_1D,closure_stencil,CartesianBoundary{1,Upper}())
+            @test op_r isa TensorMapping{T,0,1} where T
+        end
+
+        @testset "2D" begin
+            e_w = boundary_operator(g_2D,closure_stencil,CartesianBoundary{1,Upper}())
+            @test e_w isa InflatedTensorMapping
+            @test e_w isa TensorMapping{T,1,2} where T
+        end
+    end
+
+    op_l = boundary_operator(g_1D, closure_stencil, CartesianBoundary{1,Lower}())
+    op_r = boundary_operator(g_1D, closure_stencil, CartesianBoundary{1,Upper}())
+
+    op_w = boundary_operator(g_2D, closure_stencil, CartesianBoundary{1,Lower}())
+    op_e = boundary_operator(g_2D, closure_stencil, CartesianBoundary{1,Upper}())
+    op_s = boundary_operator(g_2D, closure_stencil, CartesianBoundary{2,Lower}())
+    op_n = boundary_operator(g_2D, closure_stencil, CartesianBoundary{2,Upper}())
+
+    @testset "Sizes" begin
+        @testset "1D" begin
+            @test domain_size(op_l) == (11,)
+            @test domain_size(op_r) == (11,)
+
+            @test range_size(op_l) == ()
+            @test range_size(op_r) == ()
+        end
+
+        @testset "2D" begin
+            @test domain_size(op_w) == (11,15)
+            @test domain_size(op_e) == (11,15)
+            @test domain_size(op_s) == (11,15)
+            @test domain_size(op_n) == (11,15)
+
+            @test range_size(op_w) == (15,)
+            @test range_size(op_e) == (15,)
+            @test range_size(op_s) == (11,)
+            @test range_size(op_n) == (11,)
+        end
+    end
+
+    @testset "Application" begin
+        @testset "1D" begin
+            v = evalOn(g_1D,x->1+x^2)
+            u = fill(3.124)
+            @test (op_l*v)[] == 2*v[1] + v[2] + 3*v[3]
+            @test (op_r*v)[] == 2*v[end] + v[end-1] + 3*v[end-2]
+            @test (op_r*v)[1] == 2*v[end] + v[end-1] + 3*v[end-2]
+            @test op_l'*u == [2*u[]; u[]; 3*u[]; zeros(8)]
+            @test op_r'*u == [zeros(8); 3*u[]; u[]; 2*u[]]
+        end
+
+        @testset "2D" begin
+            v = rand(size(g_2D)...)
+            u = fill(3.124)
+            @test op_w*v ≈ 2*v[1,:] + v[2,:] + 3*v[3,:] rtol = 1e-14
+            @test op_e*v ≈ 2*v[end,:] + v[end-1,:] + 3*v[end-2,:] rtol = 1e-14
+            @test op_s*v ≈ 2*v[:,1] + v[:,2] + 3*v[:,3] rtol = 1e-14
+            @test op_n*v ≈ 2*v[:,end] + v[:,end-1] + 3*v[:,end-2] rtol = 1e-14
+
+
+            g_x = rand(size(g_2D)[1])
+            g_y = rand(size(g_2D)[2])
+
+            G_w = zeros(Float64, size(g_2D)...)
+            G_w[1,:] = 2*g_y
+            G_w[2,:] = g_y
+            G_w[3,:] = 3*g_y
+
+            G_e = zeros(Float64, size(g_2D)...)
+            G_e[end,:] = 2*g_y
+            G_e[end-1,:] = g_y
+            G_e[end-2,:] = 3*g_y
+
+            G_s = zeros(Float64, size(g_2D)...)
+            G_s[:,1] = 2*g_x
+            G_s[:,2] = g_x
+            G_s[:,3] = 3*g_x
+
+            G_n = zeros(Float64, size(g_2D)...)
+            G_n[:,end] = 2*g_x
+            G_n[:,end-1] = g_x
+            G_n[:,end-2] = 3*g_x
+
+            @test op_w'*g_y == G_w
+            @test op_e'*g_y == G_e
+            @test op_s'*g_x == G_s
+            @test op_n'*g_x == G_n
+       end
+
+       @testset "Regions" begin
+            u = fill(3.124)
+            @test (op_l'*u)[Index(1,Lower)] == 2*u[]
+            @test (op_l'*u)[Index(2,Lower)] == u[]
+            @test (op_l'*u)[Index(6,Interior)] == 0
+            @test (op_l'*u)[Index(10,Upper)] == 0
+            @test (op_l'*u)[Index(11,Upper)] == 0
+
+            @test (op_r'*u)[Index(1,Lower)] == 0
+            @test (op_r'*u)[Index(2,Lower)] == 0
+            @test (op_r'*u)[Index(6,Interior)] == 0
+            @test (op_r'*u)[Index(10,Upper)] == u[]
+            @test (op_r'*u)[Index(11,Upper)] == 2*u[]
+       end
+    end
+
+    @testset "Inferred" begin
+        v = ones(Float64, 11)
+        u = fill(1.)
+
+        @inferred apply(op_l, v)
+        @inferred apply(op_r, v)
+
+        @inferred apply_transpose(op_l, u, 4)
+        @inferred apply_transpose(op_l, u, Index(1,Lower))
+        @inferred apply_transpose(op_l, u, Index(2,Lower))
+        @inferred apply_transpose(op_l, u, Index(6,Interior))
+        @inferred apply_transpose(op_l, u, Index(10,Upper))
+        @inferred apply_transpose(op_l, u, Index(11,Upper))
+
+        @inferred apply_transpose(op_r, u, 4)
+        @inferred apply_transpose(op_r, u, Index(1,Lower))
+        @inferred apply_transpose(op_r, u, Index(2,Lower))
+        @inferred apply_transpose(op_r, u, Index(6,Interior))
+        @inferred apply_transpose(op_r, u, Index(10,Upper))
+        @inferred apply_transpose(op_r, u, Index(11,Upper))
+    end
+
+end
+
+@testset "boundary_restriction" begin
+    op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+    g_1D = EquidistantGrid(11, 0.0, 1.0)
+    g_2D = EquidistantGrid((11,15), (0.0, 0.0), (1.0,1.0))
+
+    @testset "boundary_restriction" begin
+        @testset "1D" begin
+            e_l = boundary_restriction(g_1D,op.eClosure,Lower())
+            @test e_l == boundary_restriction(g_1D,op.eClosure,CartesianBoundary{1,Lower}())
+            @test e_l == BoundaryOperator(g_1D,op.eClosure,Lower())
+            @test e_l isa BoundaryOperator{T,Lower} where T
+            @test e_l isa TensorMapping{T,0,1} where T
+
+            e_r = boundary_restriction(g_1D,op.eClosure,Upper())
+            @test e_r == boundary_restriction(g_1D,op.eClosure,CartesianBoundary{1,Upper}())
+            @test e_r == BoundaryOperator(g_1D,op.eClosure,Upper())
+            @test e_r isa BoundaryOperator{T,Upper} where T
+            @test e_r isa TensorMapping{T,0,1} where T
+        end
+
+        @testset "2D" begin
+            e_w = boundary_restriction(g_2D,op.eClosure,CartesianBoundary{1,Upper}())
+            @test e_w isa InflatedTensorMapping
+            @test e_w isa TensorMapping{T,1,2} where T
+        end
+    end
+
+    @testset "Application" begin
+        @testset "1D" begin
+            e_l = boundary_restriction(g_1D, op.eClosure, CartesianBoundary{1,Lower}())
+            e_r = boundary_restriction(g_1D, op.eClosure, CartesianBoundary{1,Upper}())
+
+            v = evalOn(g_1D,x->1+x^2)
+            u = fill(3.124)
+
+            @test (e_l*v)[] == v[1]
+            @test (e_r*v)[] == v[end]
+            @test (e_r*v)[1] == v[end]
+        end
+
+        @testset "2D" begin
+            e_w = boundary_restriction(g_2D, op.eClosure, CartesianBoundary{1,Lower}())
+            e_e = boundary_restriction(g_2D, op.eClosure, CartesianBoundary{1,Upper}())
+            e_s = boundary_restriction(g_2D, op.eClosure, CartesianBoundary{2,Lower}())
+            e_n = boundary_restriction(g_2D, op.eClosure, CartesianBoundary{2,Upper}())
+
+            v = rand(11, 15)
+            u = fill(3.124)
+
+            @test e_w*v == v[1,:]
+            @test e_e*v == v[end,:]
+            @test e_s*v == v[:,1]
+            @test e_n*v == v[:,end]
+       end
+    end
+end
+
+@testset "normal_derivative" begin
+    g_1D = EquidistantGrid(11, 0.0, 1.0)
+    g_2D = EquidistantGrid((11,12), (0.0, 0.0), (1.0,1.0))
+    @testset "normal_derivative" begin
+        op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+        @testset "1D" begin
+            d_l = normal_derivative(g_1D, op.dClosure, Lower())
+            @test d_l == normal_derivative(g_1D, op.dClosure, CartesianBoundary{1,Lower}())
+            @test d_l isa BoundaryOperator{T,Lower} where T
+            @test d_l isa TensorMapping{T,0,1} where T
+        end
+        @testset "2D" begin
+            op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+            d_w = normal_derivative(g_2D, op.dClosure, CartesianBoundary{1,Lower}())
+            d_n = normal_derivative(g_2D, op.dClosure, CartesianBoundary{2,Upper}())
+            Ix = IdentityMapping{Float64}((size(g_2D)[1],))
+            Iy = IdentityMapping{Float64}((size(g_2D)[2],))
+            d_l = normal_derivative(restrict(g_2D,1),op.dClosure,Lower())
+            d_r = normal_derivative(restrict(g_2D,2),op.dClosure,Upper())
+            @test d_w ==  d_l⊗Iy
+            @test d_n ==  Ix⊗d_r
+            @test d_w isa TensorMapping{T,1,2} where T
+            @test d_n isa TensorMapping{T,1,2} where T
+        end
+    end
+    @testset "Accuracy" begin
+        v = evalOn(g_2D, (x,y)-> x^2 + (y-1)^2 + x*y)
+        v∂x = evalOn(g_2D, (x,y)-> 2*x + y)
+        v∂y = evalOn(g_2D, (x,y)-> 2*(y-1) + x)
+        # TODO: Test for higher order polynomials?
+        @testset "2nd order" begin
+            op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=2)
+            d_w = normal_derivative(g_2D, op.dClosure, CartesianBoundary{1,Lower}())
+            d_e = normal_derivative(g_2D, op.dClosure, CartesianBoundary{1,Upper}())
+            d_s = normal_derivative(g_2D, op.dClosure, CartesianBoundary{2,Lower}())
+            d_n = normal_derivative(g_2D, op.dClosure, CartesianBoundary{2,Upper}())
+
+            @test d_w*v ≈ v∂x[1,:] atol = 1e-13
+            @test d_e*v ≈ -v∂x[end,:] atol = 1e-13
+            @test d_s*v ≈ v∂y[:,1] atol = 1e-13
+            @test d_n*v ≈ -v∂y[:,end] atol = 1e-13
+        end
+
+        @testset "4th order" begin
+            op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
+            d_w = normal_derivative(g_2D, op.dClosure, CartesianBoundary{1,Lower}())
+            d_e = normal_derivative(g_2D, op.dClosure, CartesianBoundary{1,Upper}())
+            d_s = normal_derivative(g_2D, op.dClosure, CartesianBoundary{2,Lower}())
+            d_n = normal_derivative(g_2D, op.dClosure, CartesianBoundary{2,Upper}())
+
+            @test d_w*v ≈ v∂x[1,:] atol = 1e-13
+            @test d_e*v ≈ -v∂x[end,:] atol = 1e-13
+            @test d_s*v ≈ v∂y[:,1] atol = 1e-13
+            @test d_n*v ≈ -v∂y[:,end] atol = 1e-13
+        end
+    end
+end
+
+end
--- a/test/SbpOperators/testSbpOperators.jl	Sat Feb 20 20:36:27 2021 +0100
+++ /dev/null	Thu Jan 01 00:00:00 1970 +0000
@@ -1,832 +0,0 @@
-using Test
-using Sbplib.SbpOperators
-using Sbplib.Grids
-using Sbplib.RegionIndices
-using Sbplib.LazyTensors
-using LinearAlgebra
-using TOML
-
-import Sbplib.SbpOperators.Stencil
-import Sbplib.SbpOperators.VolumeOperator
-import Sbplib.SbpOperators.volume_operator
-import Sbplib.SbpOperators.BoundaryOperator
-import Sbplib.SbpOperators.boundary_operator
-import Sbplib.SbpOperators.even
-import Sbplib.SbpOperators.odd
-
-
-@testset "SbpOperators" begin
-
-@testset "Stencil" begin
-    s = Stencil((-2,2), (1.,2.,2.,3.,4.))
-    @test s isa Stencil{Float64, 5}
-
-    @test eltype(s) == Float64
-    @test SbpOperators.scale(s, 2) == Stencil((-2,2), (2.,4.,4.,6.,8.))
-
-    @test Stencil(1,2,3,4; center=1) == Stencil((0, 3),(1,2,3,4))
-    @test Stencil(1,2,3,4; center=2) == Stencil((-1, 2),(1,2,3,4))
-    @test Stencil(1,2,3,4; center=4) == Stencil((-3, 0),(1,2,3,4))
-
-    @test CenteredStencil(1,2,3,4,5) == Stencil((-2, 2), (1,2,3,4,5))
-    @test_throws ArgumentError CenteredStencil(1,2,3,4)
-end
-
-@testset "parse_rational" begin
-    @test SbpOperators.parse_rational("1") isa Rational
-    @test SbpOperators.parse_rational("1") == 1//1
-    @test SbpOperators.parse_rational("1/2") isa Rational
-    @test SbpOperators.parse_rational("1/2") == 1//2
-    @test SbpOperators.parse_rational("37/13") isa Rational
-    @test SbpOperators.parse_rational("37/13") == 37//13
-end
-
-@testset "readoperator" begin
-    toml_str = """
-        [meta]
-        type = "equidistant"
-
-        [order2]
-        H.inner = ["1"]
-
-        D1.inner_stencil = ["-1/2", "0", "1/2"]
-        D1.closure_stencils = [
-            ["-1", "1"],
-        ]
-
-        d1.closure = ["-3/2", "2", "-1/2"]
-
-        [order4]
-        H.closure = ["17/48", "59/48", "43/48", "49/48"]
-
-        D2.inner_stencil = ["-1/12","4/3","-5/2","4/3","-1/12"]
-        D2.closure_stencils = [
-            [     "2",    "-5",      "4",       "-1",     "0",     "0"],
-            [     "1",    "-2",      "1",        "0",     "0",     "0"],
-            [ "-4/43", "59/43", "-110/43",   "59/43", "-4/43",     "0"],
-            [ "-1/49",     "0",   "59/49", "-118/49", "64/49", "-4/49"],
-        ]
-    """
-
-    parsed_toml = TOML.parse(toml_str)
-    @testset "get_stencil" begin
-        @test get_stencil(parsed_toml, "order2", "D1", "inner_stencil") == Stencil(-1/2, 0., 1/2, center=2)
-        @test get_stencil(parsed_toml, "order2", "D1", "inner_stencil", center=1) == Stencil(-1/2, 0., 1/2; center=1)
-        @test get_stencil(parsed_toml, "order2", "D1", "inner_stencil", center=3) == Stencil(-1/2, 0., 1/2; center=3)
-
-        @test get_stencil(parsed_toml, "order2", "H", "inner") == Stencil(1.; center=1)
-
-        @test_throws AssertionError get_stencil(parsed_toml, "meta", "type")
-        @test_throws AssertionError get_stencil(parsed_toml, "order2", "D1", "closure_stencils")
-    end
-
-    @testset "get_stencils" begin
-        @test get_stencils(parsed_toml, "order2", "D1", "closure_stencils", centers=(1,)) == (Stencil(-1., 1., center=1),)
-        @test get_stencils(parsed_toml, "order2", "D1", "closure_stencils", centers=(2,)) == (Stencil(-1., 1., center=2),)
-        @test get_stencils(parsed_toml, "order2", "D1", "closure_stencils", centers=[2]) == (Stencil(-1., 1., center=2),)
-
-        @test get_stencils(parsed_toml, "order4", "D2", "closure_stencils",centers=[1,1,1,1]) == (
-            Stencil(    2.,    -5.,      4.,     -1.,    0.,    0., center=1),
-            Stencil(    1.,    -2.,      1.,      0.,    0.,    0., center=1),
-            Stencil( -4/43,  59/43, -110/43,   59/43, -4/43,    0., center=1),
-            Stencil( -1/49,     0.,   59/49, -118/49, 64/49, -4/49, center=1),
-        )
-
-        @test get_stencils(parsed_toml, "order4", "D2", "closure_stencils",centers=(4,2,3,1)) == (
-            Stencil(    2.,    -5.,      4.,     -1.,    0.,    0., center=4),
-            Stencil(    1.,    -2.,      1.,      0.,    0.,    0., center=2),
-            Stencil( -4/43,  59/43, -110/43,   59/43, -4/43,    0., center=3),
-            Stencil( -1/49,     0.,   59/49, -118/49, 64/49, -4/49, center=1),
-        )
-
-        @test get_stencils(parsed_toml, "order4", "D2", "closure_stencils",centers=1:4) == (
-            Stencil(    2.,    -5.,      4.,     -1.,    0.,    0., center=1),
-            Stencil(    1.,    -2.,      1.,      0.,    0.,    0., center=2),
-            Stencil( -4/43,  59/43, -110/43,   59/43, -4/43,    0., center=3),
-            Stencil( -1/49,     0.,   59/49, -118/49, 64/49, -4/49, center=4),
-        )
-
-        @test_throws AssertionError get_stencils(parsed_toml, "order4", "D2", "closure_stencils",centers=(1,2,3))
-        @test_throws AssertionError get_stencils(parsed_toml, "order4", "D2", "closure_stencils",centers=(1,2,3,5,4))
-        @test_throws AssertionError get_stencils(parsed_toml, "order4", "D2", "inner_stencil",centers=(1,2))
-    end
-
-    @testset "get_tuple" begin
-        @test get_tuple(parsed_toml, "order2", "d1", "closure") == (-3/2, 2, -1/2)
-
-        @test_throws AssertionError get_tuple(parsed_toml, "meta", "type")
-    end
-end
-
-@testset "VolumeOperator" begin
-    inner_stencil = CenteredStencil(1/4, 2/4, 1/4)
-    closure_stencils = (Stencil(1/2, 1/2; center=1), Stencil(0.,1.; center=2))
-    g_1D = EquidistantGrid(11,0.,1.)
-    g_2D = EquidistantGrid((11,12),(0.,0.),(1.,1.))
-    g_3D = EquidistantGrid((11,12,10),(0.,0.,0.),(1.,1.,1.))
-    @testset "Constructors" begin
-        @testset "1D" begin
-            op = VolumeOperator(inner_stencil,closure_stencils,(11,),even)
-            @test op == VolumeOperator(g_1D,inner_stencil,closure_stencils,even)
-            @test op == volume_operator(g_1D,inner_stencil,closure_stencils,even,1)
-            @test op isa TensorMapping{T,1,1} where T
-        end
-        @testset "2D" begin
-            op_x = volume_operator(g_2D,inner_stencil,closure_stencils,even,1)
-            op_y = volume_operator(g_2D,inner_stencil,closure_stencils,even,2)
-            Ix = IdentityMapping{Float64}((11,))
-            Iy = IdentityMapping{Float64}((12,))
-            @test op_x == VolumeOperator(inner_stencil,closure_stencils,(11,),even)⊗Iy
-            @test op_y == Ix⊗VolumeOperator(inner_stencil,closure_stencils,(12,),even)
-            @test op_x isa TensorMapping{T,2,2} where T
-            @test op_y isa TensorMapping{T,2,2} where T
-        end
-        @testset "3D" begin
-            op_x = volume_operator(g_3D,inner_stencil,closure_stencils,even,1)
-            op_y = volume_operator(g_3D,inner_stencil,closure_stencils,even,2)
-            op_z = volume_operator(g_3D,inner_stencil,closure_stencils,even,3)
-            Ix = IdentityMapping{Float64}((11,))
-            Iy = IdentityMapping{Float64}((12,))
-            Iz = IdentityMapping{Float64}((10,))
-            @test op_x == VolumeOperator(inner_stencil,closure_stencils,(11,),even)⊗Iy⊗Iz
-            @test op_y == Ix⊗VolumeOperator(inner_stencil,closure_stencils,(12,),even)⊗Iz
-            @test op_z == Ix⊗Iy⊗VolumeOperator(inner_stencil,closure_stencils,(10,),even)
-            @test op_x isa TensorMapping{T,3,3} where T
-            @test op_y isa TensorMapping{T,3,3} where T
-            @test op_z isa TensorMapping{T,3,3} where T
-        end
-    end
-
-    @testset "Sizes" begin
-        @testset "1D" begin
-            op = volume_operator(g_1D,inner_stencil,closure_stencils,even,1)
-            @test range_size(op) == domain_size(op) == size(g_1D)
-        end
-
-        @testset "2D" begin
-            op_x = volume_operator(g_2D,inner_stencil,closure_stencils,even,1)
-            op_y = volume_operator(g_2D,inner_stencil,closure_stencils,even,2)
-            @test range_size(op_y) == domain_size(op_y) ==
-                  range_size(op_x) == domain_size(op_x) == size(g_2D)
-        end
-        @testset "3D" begin
-            op_x = volume_operator(g_3D,inner_stencil,closure_stencils,even,1)
-            op_y = volume_operator(g_3D,inner_stencil,closure_stencils,even,2)
-            op_z = volume_operator(g_3D,inner_stencil,closure_stencils,even,3)
-            @test range_size(op_z) == domain_size(op_z) ==
-                  range_size(op_y) == domain_size(op_y) ==
-                  range_size(op_x) == domain_size(op_x) == size(g_3D)
-        end
-    end
-
-    op_x = volume_operator(g_2D,inner_stencil,closure_stencils,even,1)
-    op_y = volume_operator(g_2D,inner_stencil,closure_stencils,odd,2)
-    v = zeros(size(g_2D))
-    Nx = size(g_2D)[1]
-    Ny = size(g_2D)[2]
-    for i = 1:Nx
-        v[i,:] .= i
-    end
-    rx = copy(v)
-    rx[1,:] .= 1.5
-    rx[Nx,:] .= (2*Nx-1)/2
-    ry = copy(v)
-    ry[:,Ny-1:Ny] = -v[:,Ny-1:Ny]
-
-    @testset "Application" begin
-        @test op_x*v ≈ rx rtol = 1e-14
-        @test op_y*v ≈ ry rtol = 1e-14
-    end
-
-    @testset "Regions" begin
-        @test (op_x*v)[Index(1,Lower),Index(3,Interior)] ≈ rx[1,3] rtol = 1e-14
-        @test (op_x*v)[Index(2,Lower),Index(3,Interior)] ≈ rx[2,3] rtol = 1e-14
-        @test (op_x*v)[Index(6,Interior),Index(3,Interior)] ≈ rx[6,3] rtol = 1e-14
-        @test (op_x*v)[Index(10,Upper),Index(3,Interior)] ≈ rx[10,3] rtol = 1e-14
-        @test (op_x*v)[Index(11,Upper),Index(3,Interior)] ≈ rx[11,3] rtol = 1e-14
-
-        @test_throws BoundsError (op_x*v)[Index(3,Lower),Index(3,Interior)]
-        @test_throws BoundsError (op_x*v)[Index(9,Upper),Index(3,Interior)]
-
-        @test (op_y*v)[Index(3,Interior),Index(1,Lower)] ≈ ry[3,1] rtol = 1e-14
-        @test (op_y*v)[Index(3,Interior),Index(2,Lower)] ≈ ry[3,2] rtol = 1e-14
-        @test (op_y*v)[Index(3,Interior),Index(6,Interior)] ≈ ry[3,6] rtol = 1e-14
-        @test (op_y*v)[Index(3,Interior),Index(11,Upper)] ≈ ry[3,11] rtol = 1e-14
-        @test (op_y*v)[Index(3,Interior),Index(12,Upper)] ≈ ry[3,12] rtol = 1e-14
-
-        @test_throws BoundsError (op_y*v)[Index(3,Interior),Index(10,Upper)]
-        @test_throws BoundsError (op_y*v)[Index(3,Interior),Index(3,Lower)]
-    end
-
-    @testset "Inferred" begin
-        @inferred apply(op_x, v,1,1)
-        @inferred apply(op_x, v, Index(1,Lower),Index(1,Lower))
-        @inferred apply(op_x, v, Index(6,Interior),Index(1,Lower))
-        @inferred apply(op_x, v, Index(11,Upper),Index(1,Lower))
-
-        @inferred apply(op_y, v,1,1)
-        @inferred apply(op_y, v, Index(1,Lower),Index(1,Lower))
-        @inferred apply(op_y, v, Index(1,Lower),Index(6,Interior))
-        @inferred apply(op_y, v, Index(1,Lower),Index(11,Upper))
-    end
-
-end
-
-@testset "SecondDerivative" begin
-    op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-    Lx = 3.5
-    Ly = 3.
-    g_1D = EquidistantGrid(121, 0.0, Lx)
-    g_2D = EquidistantGrid((121,123), (0.0, 0.0), (Lx, Ly))
-
-    @testset "Constructors" begin
-        @testset "1D" begin
-            Dₓₓ = second_derivative(g_1D,op.innerStencil,op.closureStencils)
-            @test Dₓₓ == second_derivative(g_1D,op.innerStencil,op.closureStencils,1)
-            @test Dₓₓ isa VolumeOperator
-        end
-        @testset "2D" begin
-            Dₓₓ = second_derivative(g_2D,op.innerStencil,op.closureStencils,1)
-            D2 = second_derivative(g_1D,op.innerStencil,op.closureStencils)
-            I = IdentityMapping{Float64}(size(g_2D)[2])
-            @test Dₓₓ == D2⊗I
-            @test Dₓₓ isa TensorMapping{T,2,2} where T
-        end
-    end
-
-    # Exact differentiation is measured point-wise. In other cases
-    # the error is measured in the l2-norm.
-    @testset "Accuracy" begin
-        @testset "1D" begin
-            l2(v) = sqrt(spacing(g_1D)[1]*sum(v.^2));
-            monomials = ()
-            maxOrder = 4;
-            for i = 0:maxOrder-1
-                f_i(x) = 1/factorial(i)*x^i
-                monomials = (monomials...,evalOn(g_1D,f_i))
-            end
-            v = evalOn(g_1D,x -> sin(x))
-            vₓₓ = evalOn(g_1D,x -> -sin(x))
-
-            # 2nd order interior stencil, 1nd order boundary stencil,
-            # implies that L*v should be exact for monomials up to order 2.
-            @testset "2nd order" begin
-                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=2)
-                Dₓₓ = second_derivative(g_1D,op.innerStencil,op.closureStencils)
-                @test Dₓₓ*monomials[1] ≈ zeros(Float64,size(g_1D)...) atol = 5e-10
-                @test Dₓₓ*monomials[2] ≈ zeros(Float64,size(g_1D)...) atol = 5e-10
-                @test Dₓₓ*monomials[3] ≈ monomials[1] atol = 5e-10
-                @test Dₓₓ*v ≈ vₓₓ rtol = 5e-2 norm = l2
-            end
-
-            # 4th order interior stencil, 2nd order boundary stencil,
-            # implies that L*v should be exact for monomials up to order 3.
-            @testset "4th order" begin
-                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-                Dₓₓ = second_derivative(g_1D,op.innerStencil,op.closureStencils)
-                # NOTE: high tolerances for checking the "exact" differentiation
-                # due to accumulation of round-off errors/cancellation errors?
-                @test Dₓₓ*monomials[1] ≈ zeros(Float64,size(g_1D)...) atol = 5e-10
-                @test Dₓₓ*monomials[2] ≈ zeros(Float64,size(g_1D)...) atol = 5e-10
-                @test Dₓₓ*monomials[3] ≈ monomials[1] atol = 5e-10
-                @test Dₓₓ*monomials[4] ≈ monomials[2] atol = 5e-10
-                @test Dₓₓ*v ≈ vₓₓ rtol = 5e-4 norm = l2
-            end
-        end
-
-        @testset "2D" begin
-            l2(v) = sqrt(prod(spacing(g_2D))*sum(v.^2));
-            binomials = ()
-            maxOrder = 4;
-            for i = 0:maxOrder-1
-                f_i(x,y) = 1/factorial(i)*y^i + x^i
-                binomials = (binomials...,evalOn(g_2D,f_i))
-            end
-            v = evalOn(g_2D, (x,y) -> sin(x)+cos(y))
-            v_yy = evalOn(g_2D,(x,y) -> -cos(y))
-
-            # 2nd order interior stencil, 1st order boundary stencil,
-            # implies that L*v should be exact for binomials up to order 2.
-            @testset "2nd order" begin
-                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=2)
-                Dyy = second_derivative(g_2D,op.innerStencil,op.closureStencils,2)
-                @test Dyy*binomials[1] ≈ zeros(Float64,size(g_2D)...) atol = 5e-9
-                @test Dyy*binomials[2] ≈ zeros(Float64,size(g_2D)...) atol = 5e-9
-                @test Dyy*binomials[3] ≈ evalOn(g_2D,(x,y)->1.) atol = 5e-9
-                @test Dyy*v ≈ v_yy rtol = 5e-2 norm = l2
-            end
-
-            # 4th order interior stencil, 2nd order boundary stencil,
-            # implies that L*v should be exact for binomials up to order 3.
-            @testset "4th order" begin
-                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-                Dyy = second_derivative(g_2D,op.innerStencil,op.closureStencils,2)
-                # NOTE: high tolerances for checking the "exact" differentiation
-                # due to accumulation of round-off errors/cancellation errors?
-                @test Dyy*binomials[1] ≈ zeros(Float64,size(g_2D)...) atol = 5e-9
-                @test Dyy*binomials[2] ≈ zeros(Float64,size(g_2D)...) atol = 5e-9
-                @test Dyy*binomials[3] ≈ evalOn(g_2D,(x,y)->1.) atol = 5e-9
-                @test Dyy*binomials[4] ≈ evalOn(g_2D,(x,y)->y) atol = 5e-9
-                @test Dyy*v ≈ v_yy rtol = 5e-4 norm = l2
-            end
-        end
-    end
-end
-
-@testset "Laplace" begin
-    g_1D = EquidistantGrid(101, 0.0, 1.)
-    g_3D = EquidistantGrid((51,101,52), (0.0, -1.0, 0.0), (1., 1., 1.))
-    @testset "Constructors" begin
-        op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-        @testset "1D" begin
-            L = laplace(g_1D, op.innerStencil, op.closureStencils)
-            @test L == second_derivative(g_1D, op.innerStencil, op.closureStencils)
-            @test L isa TensorMapping{T,1,1}  where T
-        end
-        @testset "3D" begin
-            L = laplace(g_3D, op.innerStencil, op.closureStencils)
-            @test L isa TensorMapping{T,3,3} where T
-            Dxx = second_derivative(g_3D, op.innerStencil, op.closureStencils,1)
-            Dyy = second_derivative(g_3D, op.innerStencil, op.closureStencils,2)
-            Dzz = second_derivative(g_3D, op.innerStencil, op.closureStencils,3)
-            @test L == Dxx + Dyy + Dzz
-        end
-    end
-
-    # Exact differentiation is measured point-wise. In other cases
-    # the error is measured in the l2-norm.
-    @testset "Accuracy" begin
-        l2(v) = sqrt(prod(spacing(g_3D))*sum(v.^2));
-        polynomials = ()
-        maxOrder = 4;
-        for i = 0:maxOrder-1
-            f_i(x,y,z) = 1/factorial(i)*(y^i + x^i + z^i)
-            polynomials = (polynomials...,evalOn(g_3D,f_i))
-        end
-        v = evalOn(g_3D, (x,y,z) -> sin(x) + cos(y) + exp(z))
-        Δv = evalOn(g_3D,(x,y,z) -> -sin(x) - cos(y) + exp(z))
-
-        # 2nd order interior stencil, 1st order boundary stencil,
-        # implies that L*v should be exact for binomials up to order 2.
-        @testset "2nd order" begin
-            op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=2)
-            L = laplace(g_3D,op.innerStencil,op.closureStencils)
-            @test L*polynomials[1] ≈ zeros(Float64, size(g_3D)...) atol = 5e-9
-            @test L*polynomials[2] ≈ zeros(Float64, size(g_3D)...) atol = 5e-9
-            @test L*polynomials[3] ≈ polynomials[1] atol = 5e-9
-            @test L*v ≈ Δv rtol = 5e-2 norm = l2
-        end
-
-        # 4th order interior stencil, 2nd order boundary stencil,
-        # implies that L*v should be exact for binomials up to order 3.
-        @testset "4th order" begin
-            op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-            L = laplace(g_3D,op.innerStencil,op.closureStencils)
-            # NOTE: high tolerances for checking the "exact" differentiation
-            # due to accumulation of round-off errors/cancellation errors?
-            @test L*polynomials[1] ≈ zeros(Float64, size(g_3D)...) atol = 5e-9
-            @test L*polynomials[2] ≈ zeros(Float64, size(g_3D)...) atol = 5e-9
-            @test L*polynomials[3] ≈ polynomials[1] atol = 5e-9
-            @test L*polynomials[4] ≈ polynomials[2] atol = 5e-9
-            @test L*v ≈ Δv rtol = 5e-4 norm = l2
-        end
-    end
-end
-
-@testset "Diagonal-stencil inner_product" begin
-    Lx = π/2.
-    Ly = Float64(π)
-    Lz = 1.
-    g_1D = EquidistantGrid(77, 0.0, Lx)
-    g_2D = EquidistantGrid((77,66), (0.0, 0.0), (Lx,Ly))
-    g_3D = EquidistantGrid((10,10, 10), (0.0, 0.0, 0.0), (Lx,Ly,Lz))
-    integral(H,v) = sum(H*v)
-    @testset "inner_product" begin
-        op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-        @testset "0D" begin
-            H = inner_product(EquidistantGrid{Float64}(),op.quadratureClosure)
-            @test H == IdentityMapping{Float64}()
-            @test H isa TensorMapping{T,0,0} where T
-        end
-        @testset "1D" begin
-            H = inner_product(g_1D,op.quadratureClosure)
-            inner_stencil = CenteredStencil(1.)
-            @test H == inner_product(g_1D,op.quadratureClosure,inner_stencil)
-            @test H isa TensorMapping{T,1,1} where T
-        end
-        @testset "2D" begin
-            H = inner_product(g_2D,op.quadratureClosure)
-            H_x = inner_product(restrict(g_2D,1),op.quadratureClosure)
-            H_y = inner_product(restrict(g_2D,2),op.quadratureClosure)
-            @test H == H_x⊗H_y
-            @test H isa TensorMapping{T,2,2} where T
-        end
-    end
-
-    @testset "Sizes" begin
-        op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-        @testset "1D" begin
-            H = inner_product(g_1D,op.quadratureClosure)
-            @test domain_size(H) == size(g_1D)
-            @test range_size(H) == size(g_1D)
-        end
-        @testset "2D" begin
-            H = inner_product(g_2D,op.quadratureClosure)
-            @test domain_size(H) == size(g_2D)
-            @test range_size(H) == size(g_2D)
-        end
-    end
-
-    @testset "Accuracy" begin
-        @testset "1D" begin
-            v = ()
-            for i = 0:4
-                f_i(x) = 1/factorial(i)*x^i
-                v = (v...,evalOn(g_1D,f_i))
-            end
-            u = evalOn(g_1D,x->sin(x))
-
-            @testset "2nd order" begin
-                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=2)
-                H = inner_product(g_1D,op.quadratureClosure)
-                for i = 1:2
-                    @test integral(H,v[i]) ≈ v[i+1][end] - v[i+1][1] rtol = 1e-14
-                end
-                @test integral(H,u) ≈ 1. rtol = 1e-4
-            end
-
-            @testset "4th order" begin
-                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-                H = inner_product(g_1D,op.quadratureClosure)
-                for i = 1:4
-                    @test integral(H,v[i]) ≈ v[i+1][end] -  v[i+1][1] rtol = 1e-14
-                end
-                @test integral(H,u) ≈ 1. rtol = 1e-8
-            end
-        end
-
-        @testset "2D" begin
-            b = 2.1
-            v = b*ones(Float64, size(g_2D))
-            u = evalOn(g_2D,(x,y)->sin(x)+cos(y))
-            @testset "2nd order" begin
-                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=2)
-                H = inner_product(g_2D,op.quadratureClosure)
-                @test integral(H,v) ≈ b*Lx*Ly rtol = 1e-13
-                @test integral(H,u) ≈ π rtol = 1e-4
-            end
-            @testset "4th order" begin
-                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-                H = inner_product(g_2D,op.quadratureClosure)
-                @test integral(H,v) ≈ b*Lx*Ly rtol = 1e-13
-                @test integral(H,u) ≈ π rtol = 1e-8
-            end
-        end
-    end
-end
-
-@testset "Diagonal-stencil inverse_inner_product" begin
-    Lx = π/2.
-    Ly = Float64(π)
-    g_1D = EquidistantGrid(77, 0.0, Lx)
-    g_2D = EquidistantGrid((77,66), (0.0, 0.0), (Lx,Ly))
-    @testset "inverse_inner_product" begin
-        op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-        @testset "0D" begin
-            Hi = inverse_inner_product(EquidistantGrid{Float64}(),op.quadratureClosure)
-            @test Hi == IdentityMapping{Float64}()
-            @test Hi isa TensorMapping{T,0,0} where T
-        end
-        @testset "1D" begin
-            Hi = inverse_inner_product(g_1D, op.quadratureClosure);
-            inner_stencil = CenteredStencil(1.)
-            closures = ()
-            for i = 1:length(op.quadratureClosure)
-                closures = (closures...,Stencil(op.quadratureClosure[i].range,1.0./op.quadratureClosure[i].weights))
-            end
-            @test Hi == inverse_inner_product(g_1D,closures,inner_stencil)
-            @test Hi isa TensorMapping{T,1,1} where T
-        end
-        @testset "2D" begin
-            Hi = inverse_inner_product(g_2D,op.quadratureClosure)
-            Hi_x = inverse_inner_product(restrict(g_2D,1),op.quadratureClosure)
-            Hi_y = inverse_inner_product(restrict(g_2D,2),op.quadratureClosure)
-            @test Hi == Hi_x⊗Hi_y
-            @test Hi isa TensorMapping{T,2,2} where T
-        end
-    end
-
-    @testset "Sizes" begin
-        op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-        @testset "1D" begin
-            Hi = inverse_inner_product(g_1D,op.quadratureClosure)
-            @test domain_size(Hi) == size(g_1D)
-            @test range_size(Hi) == size(g_1D)
-        end
-        @testset "2D" begin
-            Hi = inverse_inner_product(g_2D,op.quadratureClosure)
-            @test domain_size(Hi) == size(g_2D)
-            @test range_size(Hi) == size(g_2D)
-        end
-    end
-
-    @testset "Accuracy" begin
-        @testset "1D" begin
-            v = evalOn(g_1D,x->sin(x))
-            u = evalOn(g_1D,x->x^3-x^2+1)
-            @testset "2nd order" begin
-                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=2)
-                H = inner_product(g_1D,op.quadratureClosure)
-                Hi = inverse_inner_product(g_1D,op.quadratureClosure)
-                @test Hi*H*v ≈ v rtol = 1e-15
-                @test Hi*H*u ≈ u rtol = 1e-15
-            end
-            @testset "4th order" begin
-                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-                H = inner_product(g_1D,op.quadratureClosure)
-                Hi = inverse_inner_product(g_1D,op.quadratureClosure)
-                @test Hi*H*v ≈ v rtol = 1e-15
-                @test Hi*H*u ≈ u rtol = 1e-15
-            end
-        end
-        @testset "2D" begin
-            v = evalOn(g_2D,(x,y)->sin(x)+cos(y))
-            u = evalOn(g_2D,(x,y)->x*y + x^5 - sqrt(y))
-            @testset "2nd order" begin
-                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=2)
-                H = inner_product(g_2D,op.quadratureClosure)
-                Hi = inverse_inner_product(g_2D,op.quadratureClosure)
-                @test Hi*H*v ≈ v rtol = 1e-15
-                @test Hi*H*u ≈ u rtol = 1e-15
-            end
-            @testset "4th order" begin
-                op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-                H = inner_product(g_2D,op.quadratureClosure)
-                Hi = inverse_inner_product(g_2D,op.quadratureClosure)
-                @test Hi*H*v ≈ v rtol = 1e-15
-                @test Hi*H*u ≈ u rtol = 1e-15
-            end
-        end
-    end
-end
-
-@testset "BoundaryOperator" begin
-    closure_stencil = Stencil((0,2), (2.,1.,3.))
-    g_1D = EquidistantGrid(11, 0.0, 1.0)
-    g_2D = EquidistantGrid((11,15), (0.0, 0.0), (1.0,1.0))
-
-    @testset "Constructors" begin
-        @testset "1D" begin
-            op_l = BoundaryOperator{Lower}(closure_stencil,size(g_1D)[1])
-            @test op_l == BoundaryOperator(g_1D,closure_stencil,Lower())
-            @test op_l == boundary_operator(g_1D,closure_stencil,CartesianBoundary{1,Lower}())
-            @test op_l isa TensorMapping{T,0,1} where T
-
-            op_r = BoundaryOperator{Upper}(closure_stencil,size(g_1D)[1])
-            @test op_r == BoundaryOperator(g_1D,closure_stencil,Upper())
-            @test op_r == boundary_operator(g_1D,closure_stencil,CartesianBoundary{1,Upper}())
-            @test op_r isa TensorMapping{T,0,1} where T
-        end
-
-        @testset "2D" begin
-            e_w = boundary_operator(g_2D,closure_stencil,CartesianBoundary{1,Upper}())
-            @test e_w isa InflatedTensorMapping
-            @test e_w isa TensorMapping{T,1,2} where T
-        end
-    end
-
-    op_l = boundary_operator(g_1D, closure_stencil, CartesianBoundary{1,Lower}())
-    op_r = boundary_operator(g_1D, closure_stencil, CartesianBoundary{1,Upper}())
-
-    op_w = boundary_operator(g_2D, closure_stencil, CartesianBoundary{1,Lower}())
-    op_e = boundary_operator(g_2D, closure_stencil, CartesianBoundary{1,Upper}())
-    op_s = boundary_operator(g_2D, closure_stencil, CartesianBoundary{2,Lower}())
-    op_n = boundary_operator(g_2D, closure_stencil, CartesianBoundary{2,Upper}())
-
-    @testset "Sizes" begin
-        @testset "1D" begin
-            @test domain_size(op_l) == (11,)
-            @test domain_size(op_r) == (11,)
-
-            @test range_size(op_l) == ()
-            @test range_size(op_r) == ()
-        end
-
-        @testset "2D" begin
-            @test domain_size(op_w) == (11,15)
-            @test domain_size(op_e) == (11,15)
-            @test domain_size(op_s) == (11,15)
-            @test domain_size(op_n) == (11,15)
-
-            @test range_size(op_w) == (15,)
-            @test range_size(op_e) == (15,)
-            @test range_size(op_s) == (11,)
-            @test range_size(op_n) == (11,)
-        end
-    end
-
-    @testset "Application" begin
-        @testset "1D" begin
-            v = evalOn(g_1D,x->1+x^2)
-            u = fill(3.124)
-            @test (op_l*v)[] == 2*v[1] + v[2] + 3*v[3]
-            @test (op_r*v)[] == 2*v[end] + v[end-1] + 3*v[end-2]
-            @test (op_r*v)[1] == 2*v[end] + v[end-1] + 3*v[end-2]
-            @test op_l'*u == [2*u[]; u[]; 3*u[]; zeros(8)]
-            @test op_r'*u == [zeros(8); 3*u[]; u[]; 2*u[]]
-        end
-
-        @testset "2D" begin
-            v = rand(size(g_2D)...)
-            u = fill(3.124)
-            @test op_w*v ≈ 2*v[1,:] + v[2,:] + 3*v[3,:] rtol = 1e-14
-            @test op_e*v ≈ 2*v[end,:] + v[end-1,:] + 3*v[end-2,:] rtol = 1e-14
-            @test op_s*v ≈ 2*v[:,1] + v[:,2] + 3*v[:,3] rtol = 1e-14
-            @test op_n*v ≈ 2*v[:,end] + v[:,end-1] + 3*v[:,end-2] rtol = 1e-14
-
-
-            g_x = rand(size(g_2D)[1])
-            g_y = rand(size(g_2D)[2])
-
-            G_w = zeros(Float64, size(g_2D)...)
-            G_w[1,:] = 2*g_y
-            G_w[2,:] = g_y
-            G_w[3,:] = 3*g_y
-
-            G_e = zeros(Float64, size(g_2D)...)
-            G_e[end,:] = 2*g_y
-            G_e[end-1,:] = g_y
-            G_e[end-2,:] = 3*g_y
-
-            G_s = zeros(Float64, size(g_2D)...)
-            G_s[:,1] = 2*g_x
-            G_s[:,2] = g_x
-            G_s[:,3] = 3*g_x
-
-            G_n = zeros(Float64, size(g_2D)...)
-            G_n[:,end] = 2*g_x
-            G_n[:,end-1] = g_x
-            G_n[:,end-2] = 3*g_x
-
-            @test op_w'*g_y == G_w
-            @test op_e'*g_y == G_e
-            @test op_s'*g_x == G_s
-            @test op_n'*g_x == G_n
-       end
-
-       @testset "Regions" begin
-            u = fill(3.124)
-            @test (op_l'*u)[Index(1,Lower)] == 2*u[]
-            @test (op_l'*u)[Index(2,Lower)] == u[]
-            @test (op_l'*u)[Index(6,Interior)] == 0
-            @test (op_l'*u)[Index(10,Upper)] == 0
-            @test (op_l'*u)[Index(11,Upper)] == 0
-
-            @test (op_r'*u)[Index(1,Lower)] == 0
-            @test (op_r'*u)[Index(2,Lower)] == 0
-            @test (op_r'*u)[Index(6,Interior)] == 0
-            @test (op_r'*u)[Index(10,Upper)] == u[]
-            @test (op_r'*u)[Index(11,Upper)] == 2*u[]
-       end
-    end
-
-    @testset "Inferred" begin
-        v = ones(Float64, 11)
-        u = fill(1.)
-
-        @inferred apply(op_l, v)
-        @inferred apply(op_r, v)
-
-        @inferred apply_transpose(op_l, u, 4)
-        @inferred apply_transpose(op_l, u, Index(1,Lower))
-        @inferred apply_transpose(op_l, u, Index(2,Lower))
-        @inferred apply_transpose(op_l, u, Index(6,Interior))
-        @inferred apply_transpose(op_l, u, Index(10,Upper))
-        @inferred apply_transpose(op_l, u, Index(11,Upper))
-
-        @inferred apply_transpose(op_r, u, 4)
-        @inferred apply_transpose(op_r, u, Index(1,Lower))
-        @inferred apply_transpose(op_r, u, Index(2,Lower))
-        @inferred apply_transpose(op_r, u, Index(6,Interior))
-        @inferred apply_transpose(op_r, u, Index(10,Upper))
-        @inferred apply_transpose(op_r, u, Index(11,Upper))
-    end
-
-end
-
-@testset "boundary_restriction" begin
-    op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-    g_1D = EquidistantGrid(11, 0.0, 1.0)
-    g_2D = EquidistantGrid((11,15), (0.0, 0.0), (1.0,1.0))
-
-    @testset "boundary_restriction" begin
-        @testset "1D" begin
-            e_l = boundary_restriction(g_1D,op.eClosure,Lower())
-            @test e_l == boundary_restriction(g_1D,op.eClosure,CartesianBoundary{1,Lower}())
-            @test e_l == BoundaryOperator(g_1D,op.eClosure,Lower())
-            @test e_l isa BoundaryOperator{T,Lower} where T
-            @test e_l isa TensorMapping{T,0,1} where T
-
-            e_r = boundary_restriction(g_1D,op.eClosure,Upper())
-            @test e_r == boundary_restriction(g_1D,op.eClosure,CartesianBoundary{1,Upper}())
-            @test e_r == BoundaryOperator(g_1D,op.eClosure,Upper())
-            @test e_r isa BoundaryOperator{T,Upper} where T
-            @test e_r isa TensorMapping{T,0,1} where T
-        end
-
-        @testset "2D" begin
-            e_w = boundary_restriction(g_2D,op.eClosure,CartesianBoundary{1,Upper}())
-            @test e_w isa InflatedTensorMapping
-            @test e_w isa TensorMapping{T,1,2} where T
-        end
-    end
-
-    @testset "Application" begin
-        @testset "1D" begin
-            e_l = boundary_restriction(g_1D, op.eClosure, CartesianBoundary{1,Lower}())
-            e_r = boundary_restriction(g_1D, op.eClosure, CartesianBoundary{1,Upper}())
-
-            v = evalOn(g_1D,x->1+x^2)
-            u = fill(3.124)
-
-            @test (e_l*v)[] == v[1]
-            @test (e_r*v)[] == v[end]
-            @test (e_r*v)[1] == v[end]
-        end
-
-        @testset "2D" begin
-            e_w = boundary_restriction(g_2D, op.eClosure, CartesianBoundary{1,Lower}())
-            e_e = boundary_restriction(g_2D, op.eClosure, CartesianBoundary{1,Upper}())
-            e_s = boundary_restriction(g_2D, op.eClosure, CartesianBoundary{2,Lower}())
-            e_n = boundary_restriction(g_2D, op.eClosure, CartesianBoundary{2,Upper}())
-
-            v = rand(11, 15)
-            u = fill(3.124)
-
-            @test e_w*v == v[1,:]
-            @test e_e*v == v[end,:]
-            @test e_s*v == v[:,1]
-            @test e_n*v == v[:,end]
-       end
-    end
-end
-
-@testset "normal_derivative" begin
-    g_1D = EquidistantGrid(11, 0.0, 1.0)
-    g_2D = EquidistantGrid((11,12), (0.0, 0.0), (1.0,1.0))
-    @testset "normal_derivative" begin
-        op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-        @testset "1D" begin
-            d_l = normal_derivative(g_1D, op.dClosure, Lower())
-            @test d_l == normal_derivative(g_1D, op.dClosure, CartesianBoundary{1,Lower}())
-            @test d_l isa BoundaryOperator{T,Lower} where T
-            @test d_l isa TensorMapping{T,0,1} where T
-        end
-        @testset "2D" begin
-            op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-            d_w = normal_derivative(g_2D, op.dClosure, CartesianBoundary{1,Lower}())
-            d_n = normal_derivative(g_2D, op.dClosure, CartesianBoundary{2,Upper}())
-            Ix = IdentityMapping{Float64}((size(g_2D)[1],))
-            Iy = IdentityMapping{Float64}((size(g_2D)[2],))
-            d_l = normal_derivative(restrict(g_2D,1),op.dClosure,Lower())
-            d_r = normal_derivative(restrict(g_2D,2),op.dClosure,Upper())
-            @test d_w ==  d_l⊗Iy
-            @test d_n ==  Ix⊗d_r
-            @test d_w isa TensorMapping{T,1,2} where T
-            @test d_n isa TensorMapping{T,1,2} where T
-        end
-    end
-    @testset "Accuracy" begin
-        v = evalOn(g_2D, (x,y)-> x^2 + (y-1)^2 + x*y)
-        v∂x = evalOn(g_2D, (x,y)-> 2*x + y)
-        v∂y = evalOn(g_2D, (x,y)-> 2*(y-1) + x)
-        # TODO: Test for higher order polynomials?
-        @testset "2nd order" begin
-            op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=2)
-            d_w = normal_derivative(g_2D, op.dClosure, CartesianBoundary{1,Lower}())
-            d_e = normal_derivative(g_2D, op.dClosure, CartesianBoundary{1,Upper}())
-            d_s = normal_derivative(g_2D, op.dClosure, CartesianBoundary{2,Lower}())
-            d_n = normal_derivative(g_2D, op.dClosure, CartesianBoundary{2,Upper}())
-
-            @test d_w*v ≈ v∂x[1,:] atol = 1e-13
-            @test d_e*v ≈ -v∂x[end,:] atol = 1e-13
-            @test d_s*v ≈ v∂y[:,1] atol = 1e-13
-            @test d_n*v ≈ -v∂y[:,end] atol = 1e-13
-        end
-
-        @testset "4th order" begin
-            op = read_D2_operator(sbp_operators_path()*"standard_diagonal.toml"; order=4)
-            d_w = normal_derivative(g_2D, op.dClosure, CartesianBoundary{1,Lower}())
-            d_e = normal_derivative(g_2D, op.dClosure, CartesianBoundary{1,Upper}())
-            d_s = normal_derivative(g_2D, op.dClosure, CartesianBoundary{2,Lower}())
-            d_n = normal_derivative(g_2D, op.dClosure, CartesianBoundary{2,Upper}())
-
-            @test d_w*v ≈ v∂x[1,:] atol = 1e-13
-            @test d_e*v ≈ -v∂x[end,:] atol = 1e-13
-            @test d_s*v ≈ v∂y[:,1] atol = 1e-13
-            @test d_n*v ≈ -v∂y[:,end] atol = 1e-13
-        end
-    end
-end
-
-end
--- a/test/runtests.jl	Sat Feb 20 20:36:27 2021 +0100
+++ b/test/runtests.jl	Sat Feb 20 20:45:40 2021 +0100
@@ -6,7 +6,7 @@
     run_testfiles(path)
     run_testfiles(path, glob)
 
-Find and run all files with filenames starting with "test". If `path` is omitted the test folder is assumed.
+Find and run all files with filenames ending with "_test.jl". If `path` is omitted the test folder is assumed.
 The argument `glob` can optionally be supplied to filter which test files are run.
 """
 function run_testfiles(args)
@@ -19,7 +19,6 @@
     run_testfiles(".", glob)
 end
 
-# TODO change from prefix `test` to suffix `_test` for testfiles
 function  run_testfiles(path, glob)
     for name ∈ readdir(path)
         filepath = joinpath(path, name)
@@ -30,11 +29,7 @@
             end
         end
 
-        if !endswith(name, ".jl") ## TODO combine this into test below when switching to suffix
-            continue
-        end
-
-        if startswith(name, "test") && occursin(glob, filepath)
+        if endswith(name, "_test.jl") && occursin(glob, filepath)
             printstyled("Running "; bold=true, color=:green)
             println(filepath)
             include(filepath)