changeset 709:48a61e085e60 feature/selectable_tests

Add function for selecting tests
author Jonatan Werpers <jonatan@werpers.com>
date Sat, 20 Feb 2021 20:31:08 +0100
parents 38f9894279cd
children 44fa9a171557
files README.md test/Manifest.toml test/Project.toml test/SbpOperators/testSbpOperators.jl test/runtests.jl test/testSbpOperators.jl
diffstat 6 files changed, 896 insertions(+), 836 deletions(-) [+]
line wrap: on
line diff
diff -r 38f9894279cd -r 48a61e085e60 README.md
--- a/README.md	Mon Feb 15 11:13:12 2021 +0100
+++ b/README.md	Sat Feb 20 20:31:08 2021 +0100
@@ -10,6 +10,17 @@
 If you want to run tests from a specific file in `test/`, you can do
 ```
 julia> using Pkg
-julia> Pkg.test(test_args=["testLazyTensors"])
+julia> Pkg.test(test_args=["[glob pattern]"])
+```
+For example
+```
+julia> Pkg.test(test_args=["SbpOperators/*"])
 ```
+to run all test in the `SbpOperators` folder, or
+```
+julia> Pkg.test(test_args=["*/readoperators.jl"])
+```
+to run only the tests in files named `readoperators.jl`.
+
+
 This works by using the `@includetests` macro from the [TestSetExtensions](https://github.com/ssfrr/TestSetExtensions.jl) package. For more information, see their documentation.
diff -r 38f9894279cd -r 48a61e085e60 test/Manifest.toml
--- a/test/Manifest.toml	Mon Feb 15 11:13:12 2021 +0100
+++ b/test/Manifest.toml	Sat Feb 20 20:31:08 2021 +0100
@@ -34,6 +34,11 @@
 deps = ["Random", "Serialization", "Sockets"]
 uuid = "8ba89e20-285c-5b6f-9357-94700520ee1b"
 
+[[Glob]]
+git-tree-sha1 = "4df9f7e06108728ebf00a0a11edee4b29a482bb2"
+uuid = "c27321d9-0574-5035-807b-f59d2c89b15c"
+version = "1.3.0"
+
 [[InteractiveUtils]]
 deps = ["Markdown"]
 uuid = "b77e0a4c-d291-57a0-90e8-8db25a27a240"
diff -r 38f9894279cd -r 48a61e085e60 test/Project.toml
--- a/test/Project.toml	Mon Feb 15 11:13:12 2021 +0100
+++ b/test/Project.toml	Sat Feb 20 20:31:08 2021 +0100
@@ -1,4 +1,5 @@
 [deps]
+Glob = "c27321d9-0574-5035-807b-f59d2c89b15c"
 LinearAlgebra = "37e2e46d-f89d-539d-b4ee-838fcccc9c8e"
 TOML = "fa267f1f-6049-4f14-aa54-33bafae1ed76"
 Test = "8dfed614-e22c-5e08-85e1-65c5234f0b40"
diff -r 38f9894279cd -r 48a61e085e60 test/SbpOperators/testSbpOperators.jl
--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/SbpOperators/testSbpOperators.jl	Sat Feb 20 20:31:08 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
diff -r 38f9894279cd -r 48a61e085e60 test/runtests.jl
--- a/test/runtests.jl	Mon Feb 15 11:13:12 2021 +0100
+++ b/test/runtests.jl	Sat Feb 20 20:31:08 2021 +0100
@@ -1,6 +1,49 @@
 using Test
-using TestSetExtensions
+using Glob
+
+"""
+    run_testfiles()
+    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.
+The argument `glob` can optionally be supplied to filter which test files are run.
+"""
+function run_testfiles(args)
+    if isempty(args)
+        glob = fn"./*"
+    else
+        glob = Glob.FilenameMatch("./"*args[1]) #TBD: Allow multiple filters?
+    end
+
+    run_testfiles(".", glob)
+end
 
-@testset "All" begin
-    @includetests ARGS
+# TODO change from prefix `test` to suffix `_test` for testfiles
+function  run_testfiles(path, glob)
+    for name ∈ readdir(path)
+        filepath = joinpath(path, name)
+
+        if isdir(filepath)
+            @testset "$name" begin
+                run_testfiles(filepath, glob)
+            end
+        end
+
+        if !endswith(name, ".jl") ## TODO combine this into test below when switching to suffix
+            continue
+        end
+
+        if startswith(name, "test") && occursin(glob, filepath)
+            printstyled("Running "; bold=true, color=:green)
+            println(filepath)
+            include(filepath)
+        end
+    end
 end
+
+testsetname = isempty(ARGS) ? "Sbplib.jl" : ARGS[1]
+
+@testset "$testsetname" begin
+    run_testfiles(ARGS)
+end
diff -r 38f9894279cd -r 48a61e085e60 test/testSbpOperators.jl
--- a/test/testSbpOperators.jl	Mon Feb 15 11:13:12 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