From a38ed022dbc7914b344920698ddab7debf7f1e57 Mon Sep 17 00:00:00 2001
From: Abdulaziz <Abdulaziz.Mohamed@edu.ruhr-uni-bochum.de>
Date: Wed, 13 Nov 2024 18:39:15 +0100
Subject: [PATCH] Fix bug where boundary sets are broken for mixed grids

---
 src/Grid/utils.jl                |  1 +
 test/test_grid_addboundaryset.jl | 17 +++++++++++++++++
 2 files changed, 18 insertions(+)

diff --git a/src/Grid/utils.jl b/src/Grid/utils.jl
index ce5937010e..04400ae765 100644
--- a/src/Grid/utils.jl
+++ b/src/Grid/utils.jl
@@ -165,6 +165,7 @@ function _create_boundaryset(f::Function, grid::AbstractGrid, top::ExclusiveTopo
             cell_idx = ff_nh_idx[1]
             facet_nr = ff_nh_idx[2]
             cell = getcells(grid, cell_idx)
+            length(facets(cell)) < facet_nr && continue
             facet_nodes = facets(cell)[facet_nr]
             for (subentity_idx, subentity_nodes) in pairs(boundaryfunction(BI)(cell))
                 if Base.all(n -> n in facet_nodes, subentity_nodes)
diff --git a/test/test_grid_addboundaryset.jl b/test/test_grid_addboundaryset.jl
index ed3ca549ad..ed85602f50 100644
--- a/test/test_grid_addboundaryset.jl
+++ b/test/test_grid_addboundaryset.jl
@@ -200,4 +200,21 @@
         addboundaryfacetset!(grid, topology, "test_boundary_facetset", filter_function)
         @test getfacetset(grid, "test_boundary_facetset") == Ferrite.create_boundaryfacetset(grid, topology, filter_function)
     end
+
+    @testset "addboundaryset Mixed grid" begin
+        nodes = [Node((-1.0, 0.0)), Node((0.0, 0.0)), Node((1.0, 0.0)), Node((-1.0, 1.0)), Node((0.0, 1.0))]
+        cells = [
+            Quadrilateral((1, 2, 5, 4)),
+            Triangle((3, 5, 2)),
+        ]
+        grid = Grid(cells, nodes)
+        topology = ExclusiveTopology(grid)
+        @test extractboundary(grid, topology) == extractboundarycheck(grid)
+
+        filter_function(x) = x[1] > 0
+        addboundaryvertexset!(grid, topology, "test_boundary_vertexset", filter_function)
+        @test getvertexset(grid, "test_boundary_vertexset") == Ferrite.create_boundaryvertexset(grid, topology, filter_function)
+        addboundaryfacetset!(grid, topology, "test_boundary_facetset", filter_function)
+        @test getfacetset(grid, "test_boundary_facetset") == Ferrite.create_boundaryfacetset(grid, topology, filter_function)
+    end
 end