--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/test/Grids/tensor_grid_test.jl	Sun Jan 12 21:18:44 2025 +0100
@@ -0,0 +1,263 @@
+using Test
+using Diffinitive.Grids
+using StaticArrays
+
+@testset "TensorGrid" begin
+    g₁ = EquidistantGrid(range(0,1,length=11))
+    g₂ = EquidistantGrid(range(2,3,length=6))
+    g₃ = EquidistantGrid(1:10)
+    g₄ = ZeroDimGrid(@SVector[1,2])
+
+    @test TensorGrid(g₁, g₂) isa TensorGrid
+    @test TensorGrid(g₁, g₂) isa Grid{SVector{2,Float64}, 2}
+    @test TensorGrid(g₃, g₃) isa Grid{SVector{2,Int}, 2}
+    @test TensorGrid(g₁, g₂, g₃) isa Grid{SVector{3,Float64}, 3}
+    @test TensorGrid(g₁, g₄) isa Grid{SVector{3,Float64}, 1}
+    @test TensorGrid(g₁, g₄, g₂) isa Grid{SVector{4,Float64}, 2}
+
+    @testset "Indexing Interface" begin
+        @testset "regular indexing" begin
+            @test TensorGrid(g₁, g₂)[1,1] isa SVector{2,Float64}
+            @test TensorGrid(g₁, g₂)[1,1] == [0.0,2.0]
+            @test TensorGrid(g₁, g₂)[3,5] == [0.2,2.8]
+            @test TensorGrid(g₁, g₂)[10,6] == [0.9,3.0]
+
+            @test TensorGrid(g₁, g₃)[1,1] isa SVector{2,Float64}
+            @test TensorGrid(g₁, g₃)[1,1] == [0.0,1.0]
+
+            @test TensorGrid(g₁, g₂, g₃)[3,4,5] isa SVector{3,Float64}
+            @test TensorGrid(g₁, g₂, g₃)[3,4,5] == [0.2, 2.6, 5.0]
+
+            @test TensorGrid(g₁, g₄)[3] isa SVector{3,Float64}
+            @test TensorGrid(g₁, g₄)[3] == [0.2, 1., 2.]
+
+            @test TensorGrid(g₁, g₄, g₂)[3,2] isa SVector{4,Float64}
+            @test TensorGrid(g₁, g₄, g₂)[3,2] == [0.2, 1., 2., 2.2]
+
+            g = TensorGrid(g₁, g₂)
+            @test g[begin, begin] == g[1,1]
+            @test g[begin, end] == g[1,6]
+            @test g[end, end] == g[11,6]
+        end
+
+        @testset "cartesian indexing" begin
+            cases = [
+                (TensorGrid(g₁, g₂),     (1,1)  ),
+                (TensorGrid(g₁, g₂),     (3,5)  ),
+                (TensorGrid(g₁, g₂),     (10,6) ),
+                (TensorGrid(g₁, g₃),     (1,1)  ),
+                (TensorGrid(g₁, g₂, g₃), (3,4,5)),
+                (TensorGrid(g₁, g₄),     (3)    ),
+                (TensorGrid(g₁, g₄, g₂), (3,2)  ),
+            ]
+
+            @testset "i = $is" for (g, is) ∈ cases
+                @test g[CartesianIndex(is...)] == g[is...]
+            end
+        end
+
+        @testset "eachindex" begin
+            @test eachindex(TensorGrid(g₁, g₂)) == CartesianIndices((11,6))
+            @test eachindex(TensorGrid(g₁, g₃)) == CartesianIndices((11,10))
+            @test eachindex(TensorGrid(g₁, g₂, g₃)) == CartesianIndices((11,6,10))
+            @test eachindex(TensorGrid(g₁, g₄)) == CartesianIndices((11,))
+            @test eachindex(TensorGrid(g₁, g₄, g₂)) == CartesianIndices((11,6))
+        end
+
+        @testset "firstindex" begin
+            @test firstindex(TensorGrid(g₁, g₂, g₃), 1) == 1
+            @test firstindex(TensorGrid(g₁, g₂, g₃), 2) == 1
+            @test firstindex(TensorGrid(g₁, g₂, g₃), 3) == 1
+        end
+
+        @testset "lastindex" begin
+            @test lastindex(TensorGrid(g₁, g₂, g₃), 1) == 11
+            @test lastindex(TensorGrid(g₁, g₂, g₃), 2) == 6
+            @test lastindex(TensorGrid(g₁, g₂, g₃), 3) == 10
+        end
+    end
+
+    @testset "Iterator interface" begin
+        @test eltype(TensorGrid(g₁, g₂)) == SVector{2,Float64}
+        @test eltype(TensorGrid(g₁, g₃)) == SVector{2,Float64}
+        @test eltype(TensorGrid(g₁, g₂, g₃)) == SVector{3,Float64}
+        @test eltype(TensorGrid(g₁, g₄)) == SVector{3,Float64}
+        @test eltype(TensorGrid(g₁, g₄, g₂)) == SVector{4,Float64}
+
+        @test eltype(typeof(TensorGrid(g₁, g₂))) == SVector{2,Float64}
+        @test eltype(typeof(TensorGrid(g₁, g₃))) == SVector{2,Float64}
+        @test eltype(typeof(TensorGrid(g₁, g₂, g₃))) == SVector{3,Float64}
+        @test eltype(typeof(TensorGrid(g₁, g₄))) == SVector{3,Float64}
+        @test eltype(typeof(TensorGrid(g₁, g₄, g₂))) == SVector{4,Float64}
+
+        @test size(TensorGrid(g₁, g₂)) == (11,6)
+        @test size(TensorGrid(g₁, g₃)) == (11,10)
+        @test size(TensorGrid(g₁, g₂, g₃)) == (11,6,10)
+        @test size(TensorGrid(g₁, g₄)) == (11,)
+        @test size(TensorGrid(g₁, g₄, g₂)) == (11,6)
+
+        @test size(TensorGrid(g₁, g₂, g₃),1) == 11
+        @test size(TensorGrid(g₁, g₂, g₃),2) == 6
+        @test size(TensorGrid(g₁, g₂, g₃),3) == 10
+        @test size(TensorGrid(g₁, g₄, g₂),1) == 11
+        @test size(TensorGrid(g₁, g₄, g₂),2) == 6
+
+        @test length(TensorGrid(g₁, g₂)) == 66
+        @test length(TensorGrid(g₁, g₃)) == 110
+        @test length(TensorGrid(g₁, g₂, g₃)) == 660
+        @test length(TensorGrid(g₁, g₄)) == 11
+        @test length(TensorGrid(g₁, g₄, g₂)) == 66
+
+        @test Base.IteratorSize(TensorGrid(g₁, g₂)) == Base.HasShape{2}()
+        @test Base.IteratorSize(TensorGrid(g₁, g₃)) == Base.HasShape{2}()
+        @test Base.IteratorSize(TensorGrid(g₁, g₂, g₃)) == Base.HasShape{3}()
+        @test Base.IteratorSize(TensorGrid(g₁, g₄)) == Base.HasShape{1}()
+        @test Base.IteratorSize(TensorGrid(g₁, g₄, g₂)) == Base.HasShape{2}()
+
+        @test iterate(TensorGrid(g₁, g₂))[1] isa SVector{2,Float64}
+        @test iterate(TensorGrid(g₁, g₃))[1] isa SVector{2,Float64}
+        @test iterate(TensorGrid(g₁, g₂, g₃))[1] isa SVector{3,Float64}
+        @test iterate(TensorGrid(g₁, g₄))[1] isa SVector{3,Float64}
+        @test iterate(TensorGrid(g₁, g₄, g₂))[1] isa SVector{4,Float64}
+
+        @test collect(TensorGrid(g₁, g₂)) == [@SVector[x,y] for x ∈ range(0,1,length=11), y ∈ range(2,3,length=6)]
+        @test collect(TensorGrid(g₁, g₃)) == [@SVector[x,y] for x ∈ range(0,1,length=11), y ∈ 1:10]
+        @test collect(TensorGrid(g₁, g₂, g₃)) == [@SVector[x,y,z] for x ∈ range(0,1,length=11), y ∈ range(2,3,length=6), z ∈ 1:10]
+        @test collect(TensorGrid(g₁, g₄)) == [@SVector[x,1,2] for x ∈ range(0,1,length=11)]
+        @test collect(TensorGrid(g₁, g₄, g₂)) == [@SVector[x,1,2,y] for x ∈ range(0,1,length=11), y ∈ range(2,3,length=6)]
+    end
+
+    @testset "Base" begin
+        g₁ = EquidistantGrid(range(0,1,length=11))
+        g₂ = EquidistantGrid(range(2,3,length=6))
+        g = TensorGrid(g₁, g₂)
+
+        @test axes(g, 1) == 1:11
+        @test axes(g, 2) == 1:6
+        @test axes(g) == (1:11,1:6)
+    end
+
+    @testset "spacing" begin
+        g₁ = EquidistantGrid(range(0,1,length=11))
+        g₂ = EquidistantGrid(range(2,3,length=6))
+        g₃ = ZeroDimGrid(@SVector[1,2])
+
+        @test spacing(TensorGrid(g₁)) == (1/10,)
+        @test spacing(TensorGrid(g₂)) == (1/5,)
+
+        @test spacing(TensorGrid(g₁, g₂)) == (1/10, 1/5)
+
+        @test spacing(TensorGrid(g₁, g₃)) == (1/10,)
+        @test spacing(TensorGrid(g₃, g₂)) == (1/5,)
+
+
+        @test spacing(TensorGrid(g₁, g₂, g₁)) == (1/10, 1/5, 1/10)
+
+        @test spacing(TensorGrid(g₃, g₂, g₁)) == (1/5, 1/10)
+        @test spacing(TensorGrid(g₁, g₃, g₁)) == (1/10, 1/10)
+        @test spacing(TensorGrid(g₁, g₂, g₃)) == (1/10, 1/5)
+    end
+
+    @testset "min_spacing" begin
+        g₁ = EquidistantGrid(range(0,1,length=11))
+        g₂ = EquidistantGrid(range(2,3,length=6))
+        g₃ = ZeroDimGrid(@SVector[1,2])
+
+        @test min_spacing(TensorGrid(g₁, g₂)) == 1/10
+        @test min_spacing(TensorGrid(g₂, g₃)) == 1/5
+    end
+
+    @testset "refine" begin
+        g1(n) = EquidistantGrid(range(0,1,length=n))
+        g2(n) = EquidistantGrid(range(2,3,length=n))
+
+        @test refine(TensorGrid(g1(11), g2(6)),1) == TensorGrid(g1(11), g2(6))
+        @test refine(TensorGrid(g1(11), g2(6)),2) == TensorGrid(g1(21), g2(11))
+        @test refine(TensorGrid(g1(11), g2(6)),3) == TensorGrid(g1(31), g2(16))
+        @test refine(TensorGrid(g1(11), g₄), 1) == TensorGrid(g1(11), g₄)
+        @test refine(TensorGrid(g1(11), g₄), 2) == TensorGrid(g1(21), g₄)
+    end
+
+    @testset "coarsen" begin
+        g1(n) = EquidistantGrid(range(0,1,length=n))
+        g2(n) = EquidistantGrid(range(2,3,length=n))
+
+        @test coarsen(TensorGrid(g1(11), g2(6)),1) == TensorGrid(g1(11), g2(6))
+        @test coarsen(TensorGrid(g1(21), g2(11)),2) == TensorGrid(g1(11), g2(6))
+        @test coarsen(TensorGrid(g1(31), g2(16)),3) == TensorGrid(g1(11), g2(6))
+        @test coarsen(TensorGrid(g1(11), g₄), 1) == TensorGrid(g1(11), g₄)
+        @test coarsen(TensorGrid(g1(21), g₄), 2) == TensorGrid(g1(11), g₄)
+    end
+
+    @testset "boundary_identifiers" begin
+        @test boundary_identifiers(TensorGrid(g₁, g₂)) == map((n,id)->TensorGridBoundary{n,id}(), (1,1,2,2), (LowerBoundary,UpperBoundary,LowerBoundary,UpperBoundary))
+        @test boundary_identifiers(TensorGrid(g₁, g₄)) == (TensorGridBoundary{1,LowerBoundary}(),TensorGridBoundary{1,UpperBoundary}())
+    end
+
+    @testset "boundary_grid" begin
+        @test boundary_grid(TensorGrid(g₁, g₂), TensorGridBoundary{1, UpperBoundary}()) == TensorGrid(ZeroDimGrid(g₁[end]), g₂)
+        @test boundary_grid(TensorGrid(g₁, g₄), TensorGridBoundary{1, UpperBoundary}()) == TensorGrid(ZeroDimGrid(g₁[end]), g₄)
+    end
+
+    @testset "boundary_indices" begin
+        g₁ = EquidistantGrid(range(0,1,length=11))
+        g₂ = EquidistantGrid(range(2,3,length=6))
+        g₄ = ZeroDimGrid(@SVector[1,2])
+
+        @test boundary_indices(TensorGrid(g₁, g₂), TensorGridBoundary{1, LowerBoundary}()) == (1,:)
+        @test boundary_indices(TensorGrid(g₁, g₂), TensorGridBoundary{1, UpperBoundary}()) == (11,:)
+        @test boundary_indices(TensorGrid(g₁, g₂), TensorGridBoundary{2, LowerBoundary}()) == (:,1)
+        @test boundary_indices(TensorGrid(g₁, g₂), TensorGridBoundary{2, UpperBoundary}()) == (:,6)
+        @test boundary_indices(TensorGrid(g₁, g₄), TensorGridBoundary{1, LowerBoundary}()) == (1,)
+        @test boundary_indices(TensorGrid(g₁, g₄), TensorGridBoundary{1, UpperBoundary}()) == (11,)
+        @test boundary_indices(TensorGrid(g₄,g₁), TensorGridBoundary{2, LowerBoundary}()) == (1,)
+        @test boundary_indices(TensorGrid(g₄,g₁), TensorGridBoundary{2, UpperBoundary}()) == (11,)
+    end
+end
+
+@testset "combined_coordinate_vector_type" begin
+    @test Grids.combined_coordinate_vector_type(Float64) == Float64
+    @test Grids.combined_coordinate_vector_type(Float64, Int) == SVector{2,Float64}
+    @test Grids.combined_coordinate_vector_type(Float32, Int16, Int32) == SVector{3,Float32}
+
+    @test Grids.combined_coordinate_vector_type(SVector{2,Float64}) == SVector{2,Float64}
+    @test Grids.combined_coordinate_vector_type(SVector{2,Float64}, SVector{1,Float64}) == SVector{3,Float64}
+    @test Grids.combined_coordinate_vector_type(SVector{2,Float64}, SVector{1,Int}, SVector{3, Float32}) == SVector{6,Float64}
+end
+
+@testset "combine_coordinates" begin
+    @test Grids.combine_coordinates(1,2,3) isa SVector{3, Int}
+    @test Grids.combine_coordinates(1,2,3) == [1,2,3]
+    @test Grids.combine_coordinates(1,2.,3) isa SVector{3, Float64}
+    @test Grids.combine_coordinates(1,2.,3) == [1,2,3]
+    @test Grids.combine_coordinates(1,@SVector[2.,3]) isa SVector{3, Float64}
+    @test Grids.combine_coordinates(1,@SVector[2.,3]) == [1,2,3]
+end
+
+@testset "grid_and_local_dim_index" begin
+    cases = [
+        ((1,), 1) => (1,1),
+
+        ((1,1), 1) => (1,1),
+        ((1,1), 2) => (2,1),
+
+        ((1,2), 1) => (1,1),
+        ((1,2), 2) => (2,1),
+        ((1,2), 3) => (2,2),
+
+        ((2,1), 1) => (1,1),
+        ((2,1), 2) => (1,2),
+        ((2,1), 3) => (2,1),
+
+        ((2,1,3), 1) => (1,1),
+        ((2,1,3), 2) => (1,2),
+        ((2,1,3), 3) => (2,1),
+        ((2,1,3), 4) => (3,1),
+        ((2,1,3), 5) => (3,2),
+        ((2,1,3), 6) => (3,3),
+    ]
+
+    @testset "grid_and_local_dim_index$args" for (args, expected) ∈ cases
+        @test Grids.grid_and_local_dim_index(args...) == expected
+    end
+end