refactor(tests): reorganize tests directory to match engine structure

- Created tests/Core/Asset/ with tests for IResource, ResourceTypes, ResourceHandle, ResourceCache, ResourceDependencyGraph, ResourceGUID
- Created tests/Core/IO/ with tests for IResourceLoader, ResourcePath, ResourceFileSystem, FileArchive, ResourcePackage
- Reorganized tests/Resources/ into subdirectories: Texture/, Mesh/, Material/, Shader/, AudioClip/
- Added CMakeLists.txt for each new test subdirectory
- Fixed Material.h missing ResourceManager.h include (lost during engine refactor)
- tests/Core/CMakeLists.txt updated to include Asset/ and IO/ subdirectories

tests/Resources/Shader/test_shader_loader.cpp

@@ -0,0 +1,38 @@
+#include <gtest/gtest.h>
+#include <XCEngine/Resources/Shader/ShaderLoader.h>
+#include <XCEngine/Core/Asset/ResourceTypes.h>
+#include <XCEngine/Core/Containers/Array.h>
+
+using namespace XCEngine::Resources;
+using namespace XCEngine::Containers;
+
+namespace {
+
+TEST(ShaderLoader, GetResourceType) {
+    ShaderLoader loader;
+    EXPECT_EQ(loader.GetResourceType(), ResourceType::Shader);
+}
+
+TEST(ShaderLoader, GetSupportedExtensions) {
+    ShaderLoader loader;
+    auto extensions = loader.GetSupportedExtensions();
+    EXPECT_GE(extensions.Size(), 1u);
+}
+
+TEST(ShaderLoader, CanLoad) {
+    ShaderLoader loader;
+    EXPECT_TRUE(loader.CanLoad("test.vert"));
+    EXPECT_TRUE(loader.CanLoad("test.frag"));
+    EXPECT_TRUE(loader.CanLoad("test.glsl"));
+    EXPECT_TRUE(loader.CanLoad("test.hlsl"));
+    EXPECT_FALSE(loader.CanLoad("test.txt"));
+    EXPECT_FALSE(loader.CanLoad("test.png"));
+}
+
+TEST(ShaderLoader, LoadInvalidPath) {
+    ShaderLoader loader;
+    LoadResult result = loader.Load("invalid/path/shader.glsl");
+    EXPECT_FALSE(result);
+}
+
+} // namespace