OpenGL: Restructure tests similar to D3D12 layout

- Move old test files to new unit/integration structure
- Add OpenGL Test Fixture
- Update CMakeLists.txt for new layout
- Add OpenGL_Test_Restructuring_Plan.md

tests/RHI/OpenGL/unit/test_texture.cpp

@@ -0,0 +1,73 @@
+#include "fixtures/OpenGLTestFixture.h"
+#include "XCEngine/RHI/OpenGL/OpenGLTexture.h"
+
+using namespace XCEngine::RHI;
+
+TEST_F(OpenGLTestFixture, Texture_Initialize_2DTexture) {
+    OpenGLTexture texture;
+
+    bool result = texture.Initialize2D(64, 64, 4, nullptr, false);
+
+    ASSERT_TRUE(result);
+    EXPECT_NE(texture.GetID(), 0u);
+    EXPECT_EQ(texture.GetWidth(), 64);
+    EXPECT_EQ(texture.GetHeight(), 64);
+    EXPECT_EQ(texture.GetTextureType(), TextureType::Texture2D);
+
+    texture.Shutdown();
+}
+
+TEST_F(OpenGLTestFixture, Texture_Initialize_CubeMap) {
+    OpenGLTexture texture;
+
+    bool result = texture.InitializeCubeMap(64, 1, OpenGLFormat::RGBA8, nullptr);
+
+    ASSERT_TRUE(result);
+    EXPECT_NE(texture.GetID(), 0u);
+    EXPECT_EQ(texture.GetWidth(), 64);
+    EXPECT_EQ(texture.GetHeight(), 64);
+    EXPECT_EQ(texture.GetTextureType(), TextureType::TextureCube);
+
+    texture.Shutdown();
+}
+
+TEST_F(OpenGLTestFixture, Texture_Bind_Unbind) {
+    OpenGLTexture texture;
+    texture.Initialize2D(64, 64, 4, nullptr, false);
+
+    texture.Bind(0);
+    GLint boundTexture = 0;
+    glGetIntegerv(GL_TEXTURE_BINDING_2D, &boundTexture);
+    EXPECT_EQ(boundTexture, static_cast<GLint>(texture.GetID()));
+
+    texture.Unbind();
+    glGetIntegerv(GL_TEXTURE_BINDING_2D, &boundTexture);
+    EXPECT_EQ(boundTexture, 0);
+
+    texture.Shutdown();
+}
+
+TEST_F(OpenGLTestFixture, Texture_GenerateMipmap) {
+    OpenGLTexture texture;
+    texture.Initialize2D(64, 64, 4, nullptr, false);
+
+    texture.GenerateMipmap();
+
+    GLenum error = glGetError();
+    EXPECT_EQ(error, GL_NO_ERROR);
+
+    texture.Shutdown();
+}
+
+TEST_F(OpenGLTestFixture, Texture_SetFiltering_SetWrapping) {
+    OpenGLTexture texture;
+    texture.Initialize2D(64, 64, 4, nullptr, false);
+
+    texture.SetFiltering(GL_LINEAR_MIPMAP_LINEAR, GL_LINEAR);
+    texture.SetWrapping(GL_REPEAT, GL_REPEAT, GL_REPEAT);
+
+    GLenum error = glGetError();
+    EXPECT_EQ(error, GL_NO_ERROR);
+
+    texture.Shutdown();
+}