test(dofs): add Hex20 facet map wiring tests

test/dofs/test_hex20_facet_maps.jl

@@ -0,0 +1,53 @@
+# This file is a part of JuliaFEM.
+# License is MIT: see https://github.com/JuliaFEM/JuliaFEM.jl/blob/master/LICENSE.md
+
+using Test
+using LinearAlgebra
+using JuliaFEM
+using JuliaFEM: Hex8FacetMaps, build_hex20_facet_maps, hex20_edge_orientation_sign
+using JuliaFEM: FacetMassKernel, EdgeMassKernel
+using JuliaFEM: DOFBasedCOOAssembler, DOFBasedCOOCache, assemble!, extract_system
+
+@testset "build_hex20_facet_maps (single Hex20)" begin
+    nodes = Vec{3, Float64}[reference_coordinates(Hex20())...]
+    conn = ntuple(i -> UInt32(i), 20)
+    mesh = Mesh{Hex20}(nodes, [conn])
+    maps = build_hex20_facet_maps(mesh)
+    @test maps isa Hex8FacetMaps
+    @test maps.n_edges == 12
+    @test maps.n_faces == 6
+
+    for le in 1:12
+        @test hex20_edge_orientation_sign(conn, le) == maps.elem_edge_orientation[le, 1]
+    end
+
+    S = @DOFSet{e::DOF{Float64, Edge}}
+    elements, handler = create_elements!(mesh, Element{Hex20, Serendipity{2}, S})
+    @test handler.total_dofs == 12
+end
+
+@testset "FacetMassKernel / EdgeMassKernel on reference Hex20 (corner skeleton)" begin
+    nodes = Vec{3, Float64}[reference_coordinates(Hex20())...]
+    conn = ntuple(i -> UInt32(i), 20)
+    mesh = Mesh{Hex20}(nodes, [conn])
+    X = nodes
+
+    expected_face_area = sum(hex8_face_area_physical(X, lf) for lf in 1:6)
+    expected_edge_len = sum(hex8_edge_length_physical(X, le) for le in 1:12)
+
+    Sf = @DOFSet{flux::DOF{Float64, Face}}
+    ef, hf = create_elements!(mesh, Element{Hex20, Serendipity{2}, Sf})
+    kf = FacetMassKernel(mesh)
+    cf = DOFBasedCOOCache(ef, hf, mesh, kf)
+    assemble!(cf, DOFBasedCOOAssembler(), kf, mesh)
+    Kf, _ = extract_system(cf)
+    @test sum(diag(Matrix(Kf))) ≈ expected_face_area rtol = 1e-10
+
+    Se = @DOFSet{circ::DOF{Float64, Edge}}
+    ee, he = create_elements!(mesh, Element{Hex20, Serendipity{2}, Se})
+    ke = EdgeMassKernel(mesh)
+    ce = DOFBasedCOOCache(ee, he, mesh, ke)
+    assemble!(ce, DOFBasedCOOAssembler(), ke, mesh)
+    Ke, _ = extract_system(ce)
+    @test sum(diag(Matrix(Ke))) ≈ expected_edge_len rtol = 1e-10
+end