--- a/src/Grids/mapped_grid.jl	Wed Sep 11 09:03:55 2024 +0200
+++ b/src/Grids/mapped_grid.jl	Wed Sep 11 12:09:41 2024 +0200
@@ -77,6 +77,9 @@
         det(∂x∂ξ)
     end
 end
+# TBD: Should this be changed to calculate sqrt(g) instead?
+#       This would make it well defined also for n-dim grids embedded in higher dimensions.
+# TBD: Is there a better name? metric_determinant?
 
 function metric_tensor(g::MappedGrid)
     return map(jacobian(g)) do ∂x∂ξ

--- a/test/Grids/mapped_grid_test.jl	Wed Sep 11 09:03:55 2024 +0200
+++ b/test/Grids/mapped_grid_test.jl	Wed Sep 11 12:09:41 2024 +0200
@@ -258,6 +258,14 @@
         2η^2 - ξ
     end
     @test jacobian_determinant(g) ≈ J
+
+
+    lg = equidistant_grid((0,0), (1,1), 11, 21)
+    x̄ = map(ξ̄ -> @SVector[ξ̄[1],ξ̄[2], ξ̄[1] + ξ̄[2]], lg)
+    J = map(ξ̄ -> @SMatrix[1 0; 0 1; 1 1], lg)
+    mg = MappedGrid(lg, x̄, J)
+
+    @test_broken jacobian(mg) isa AbstractArray{2,Float64}
 end
 
 @testset "metric_tensor" begin