--- a/test/SbpOperators/volumeops/derivatives/first_derivative_test.jl	Mon Mar 21 09:32:26 2022 +0100
+++ b/test/SbpOperators/volumeops/derivatives/first_derivative_test.jl	Thu May 12 21:52:47 2022 +0200
@@ -29,12 +29,14 @@
         
         @test first_derivative(g₁, stencil_set, 1) isa LazyTensor{Float64,1,1}
         @test first_derivative(g₂, stencil_set, 2) isa LazyTensor{Float64,2,2}
+        @test first_derivative(g₁, stencil_set, 1) == first_derivative(g₁, stencil_set)
 
         interior_stencil = CenteredStencil(-1,0,1)
         closure_stencils = [Stencil(-1,1, center=1)]
 
         @test first_derivative(g₁, interior_stencil, closure_stencils, 1) isa LazyTensor{Float64,1,1}
         @test first_derivative(g₁, interior_stencil, closure_stencils, 1) isa VolumeOperator
+        @test first_derivative(g₁, interior_stencil, closure_stencils, 1) == first_derivative(g₁, interior_stencil, closure_stencils)
         @test first_derivative(g₂, interior_stencil, closure_stencils, 2) isa LazyTensor{Float64,2,2}
     end
 
@@ -69,6 +71,7 @@
     end
 
     @testset "Accuracy on function" begin
+        # 1D
         g = EquidistantGrid(30, 0.,1.)
         v = evalOn(g, x->exp(x))
         @testset for (order, tol) ∈ [(2, 6e-3),(4, 2e-4)]
@@ -77,6 +80,18 @@
 
             @test D₁*v ≈ v rtol=tol
         end
+
+        # 2D
+        g = EquidistantGrid((30,60), (0.,0.),(1.,2.))
+        v = evalOn(g, (x,y)->exp(0.8x+1.2*y))
+        @testset for (order, tol) ∈ [(2, 6e-3),(4, 3e-4)]
+            stencil_set = read_stencil_set(sbp_operators_path()*"standard_diagonal.toml"; order)
+            Dx = first_derivative(g, stencil_set, 1)
+            Dy = first_derivative(g, stencil_set, 2)
+
+            @test Dx*v ≈ 0.8v rtol=tol
+            @test Dy*v ≈ 1.2v rtol=tol
+        end
     end
 end