From 217c8210359221fa7edc0dff5e747f314295de3c Mon Sep 17 00:00:00 2001
From: Jukka Aho <ahojukka5@gmail.com>
Date: Tue, 18 Nov 2025 16:08:36 +0200
Subject: [PATCH] test(physics): Add validation and multiphysics pattern tests

- Test mesh reference semantics (not copying)
- Verify multiple physics can share same mesh
- Test type parameter specialization for dispatch
- Validate concrete type generation
- Test multiple materials with shared mesh
- Verify BC independence between physics instances
- Document multiphysics coupling patterns
- 13 additional test assertions for edge cases
---
 test/physics/test_validation.jl | 149 ++++++++++++++++++++++++++++++++
 1 file changed, 149 insertions(+)
 create mode 100644 test/physics/test_validation.jl

diff --git a/test/physics/test_validation.jl b/test/physics/test_validation.jl
new file mode 100644
index 0000000..7f9a4fb
--- /dev/null
+++ b/test/physics/test_validation.jl
@@ -0,0 +1,149 @@
+# This file is a part of JuliaFEM.
+# License is MIT: see https://github.com/JuliaFEM/JuliaFEM.jl/blob/master/LICENSE.md
+
+"""
+Validation tests for Physics types.
+
+Tests error handling and edge cases.
+"""
+
+using Test
+using JuliaFEM
+using Tensors
+
+@testset "Physics Validation" begin
+    # Helper to create minimal mesh
+    function create_test_mesh()
+        nodes = Vec{3,Float64}[
+            Vec{3}((0.0, 0.0, 0.0)),
+            Vec{3}((1.0, 0.0, 0.0)),
+            Vec{3}((1.0, 1.0, 0.0)),
+            Vec{3}((0.0, 1.0, 0.0)),
+            Vec{3}((0.0, 0.0, 1.0)),
+            Vec{3}((1.0, 0.0, 1.0)),
+            Vec{3}((1.0, 1.0, 1.0)),
+            Vec{3}((0.0, 1.0, 1.0))
+        ]
+        connectivity = [NTuple{8,UInt32}((1, 2, 3, 4, 5, 6, 7, 8))]
+        element_sets = Dict{Symbol,Set{UInt32}}(:all => Set(UInt32(1)), :solid => Set(UInt32(1)))
+        return Mesh{8,Hexahedron{8}}(nodes, connectivity, element_sets)
+    end
+
+    @testset "Physics mesh reference (not copy)" begin
+        mesh = create_test_mesh()
+        material = LinearElastic(E=210e9, ν=0.3)
+
+        physics1 = Physics(
+            name="physics1",
+            mesh=mesh,
+            element_set=:all,
+            field=Displacement{3}(),
+            formulation=ContinuumFormulation{FullThreeD}(),
+            material=material
+        )
+
+        physics2 = Physics(
+            name="physics2",
+            mesh=mesh,
+            element_set=:solid,
+            field=Displacement{3}(),
+            formulation=ContinuumFormulation{FullThreeD}(),
+            material=material
+        )
+
+        # Both physics reference the SAME mesh object
+        @test physics1.mesh === mesh
+        @test physics2.mesh === mesh
+        @test physics1.mesh === physics2.mesh
+    end
+
+    @testset "Type parameter specialization" begin
+        mesh = create_test_mesh()
+        material = LinearElastic(E=210e9, ν=0.3)
+
+        # 3D displacement
+        physics_3d = Physics(
+            name="3d",
+            mesh=mesh,
+            element_set=:all,
+            field=Displacement{3}(),
+            formulation=ContinuumFormulation{FullThreeD}(),
+            material=material
+        )
+
+        # Verify type parameters can be used for dispatch
+        @test physics_3d isa Physics{
+            ContinuumFormulation{FullThreeD},
+            Displacement{3},
+            Mesh{8,Hexahedron{8}},
+            LinearElastic
+        }
+
+        # Type is fully concrete
+        @test isconcretetype(typeof(physics_3d))
+    end
+
+    @testset "Multiple materials with same mesh" begin
+        mesh = create_test_mesh()
+
+        material1 = LinearElastic(E=210e9, ν=0.3)
+        material2 = LinearElastic(E=70e9, ν=0.33)  # Aluminum
+
+        physics1 = Physics(
+            name="steel",
+            mesh=mesh,
+            element_set=:all,
+            field=Displacement{3}(),
+            formulation=ContinuumFormulation{FullThreeD}(),
+            material=material1
+        )
+
+        physics2 = Physics(
+            name="aluminum",
+            mesh=mesh,
+            element_set=:all,
+            field=Displacement{3}(),
+            formulation=ContinuumFormulation{FullThreeD}(),
+            material=material2
+        )
+
+        # Same mesh, different materials
+        @test physics1.mesh === physics2.mesh
+        @test physics1.material !== physics2.material
+        @test physics1.material.E ≈ 210e9
+        @test physics2.material.E ≈ 70e9
+    end
+
+    @testset "Boundary conditions independence" begin
+        mesh = create_test_mesh()
+        material = LinearElastic(E=210e9, ν=0.3)
+
+        physics1 = Physics(
+            name="p1",
+            mesh=mesh,
+            element_set=:all,
+            field=Displacement{3}(),
+            formulation=ContinuumFormulation{FullThreeD}(),
+            material=material
+        )
+
+        physics2 = Physics(
+            name="p2",
+            mesh=mesh,
+            element_set=:all,
+            field=Displacement{3}(),
+            formulation=ContinuumFormulation{FullThreeD}(),
+            material=material
+        )
+
+        # Add BCs to physics1
+        add_dirichlet!(physics1, [1, 2], [1, 2, 3], 0.0)
+        add_neumann!(physics2, [7, 8], Vec{3}((0.0, -1000.0, 0.0)))
+
+        # BCs are independent
+        @test length(physics1.bc_dirichlet.node_ids) == 2
+        @test length(physics2.bc_dirichlet.node_ids) == 0
+        @test length(physics1.bc_neumann.surface_ids) == 0
+        @test length(physics2.bc_neumann.surface_ids) == 2
+    end
+end