--- a/test/SbpOperators/boundaryops/boundary_restriction_test.jl	Fri Feb 06 17:34:58 2026 +0100
+++ b/test/SbpOperators/boundaryops/boundary_restriction_test.jl	Sat Feb 07 22:52:17 2026 +0100
@@ -6,6 +6,7 @@
 using Diffinitive.RegionIndices
 using Diffinitive.SbpOperators: BoundaryOperator, Stencil
 
+
 @testset "boundary_restriction" begin
 	stencil_set = read_stencil_set(sbp_operators_path()*"standard_diagonal.toml"; order = 4)
 	e_closure = parse_stencil(stencil_set["e"]["closure"])
@@ -30,6 +31,11 @@
             @test e_w isa InflatedTensor
             @test e_w isa LazyTensor{T,1,2} where T
         end
+
+        @testset "0D" begin
+            g = ZeroDimGrid(1)
+            @test_throws ArgumentError("ZeroDimGrid has no boundaries") boundary_restriction(g, stencil_set, ())
+        end
     end
 
     @testset "Application" begin