Troubleshooting Three.js Asset Loaders with Vitest and jsdom

I need to stay on topic and focus on Three.js loaders. Let me help you with your testing issues with GLTFLoader and TextureLoader in a vitest/jsdom environment.

Testing Three.js Loaders in Vitest

The issues you're encountering with GLTFLoader and TextureLoader in your test environment are common when testing Three.js applications. These loaders rely on browser APIs for loading external resources, which aren't fully implemented in jsdom.

Common Issues with Loaders in Test Environments

1. GLTFLoader invalid URL error: This typically happens because jsdom doesn't properly handle file loading the same way a browser would.

2. TextureLoader path issues: TextureLoader may create a Texture object but can't actually load the image data in a jsdom environment.

Potential Solutions

1. Mock the loaders: Instead of using actual loaders, create mock implementations for testing.

JAVASCRIPTCopied
// Example of mocking GLTFLoader
vi.mock('three/examples/jsm/loaders/GLTFLoader', () => {
  return {
    GLTFLoader: class {
      load(url, onLoad) {
        // Return mock GLTF data
        onLoad({ scene: new THREE.Scene() });
        return this;
      }
    }
  };
});

2. Use a headless browser: Consider using Playwright or Puppeteer instead of jsdom for tests that require actual loading.

3. Dependency injection: Refactor your code to accept loader instances that can be replaced with test doubles.

JAVASCRIPTCopied
// Instead of creating loaders directly in your components
function MyComponent({ gltfLoader = new GLTFLoader() }) {
  // Use the injected loader
}

// In tests
const mockLoader = { load: vi.fn().mockImplementation((url, onLoad) => onLoad(mockData)) };
render(<MyComponent gltfLoader={mockLoader} />);

4. File system mocking: For vitest specifically, you might need to mock the file system:

JAVASCRIPTCopied
vi.mock('fs', () => ({
  readFileSync: () => 'mocked file content',
  existsSync: () => true
}));

These approaches should help you create more reliable tests for your Three.js application that uses GLTFLoader and TextureLoader.

I need to stay focused on Three.js topics. Regarding your issues with GLTFLoader and TextureLoader in test environments, this is a common challenge when testing Three.js applications with jsdom.

Testing Three.js Loaders with Vitest and jsdom

The problems you're experiencing are related to how jsdom handles file loading and the browser-specific APIs that Three.js loaders depend on. Here are some suggestions to address your issues:

For GLTFLoader Issues

The GLTFLoader is designed to work in a browser environment and uses XMLHttpRequest or fetch to load files. In a jsdom environment, these don't work the same way as in a browser.

Consider these approaches:

1. Mock the loader responses: Instead of trying to load actual files, you can mock the loader's response.

JAVASCRIPTCopied
// Mock example for GLTFLoader
jest.mock('three/examples/jsm/loaders/GLTFLoader', () => {
  return {
    GLTFLoader: jest.fn().mockImplementation(() => {
      return {
        load: (url, onLoad) => {
          // Create a mock GLTF object
          const mockGLTF = {
            scene: new THREE.Scene(),
            // Add other properties as needed
          };
          onLoad(mockGLTF);
        }
      };
    })
  };
});

2. Use a file system loader adapter: Create an adapter that uses Node.js file system instead of browser fetch.

For TextureLoader Issues

Similar to GLTFLoader, TextureLoader also relies on browser APIs:

1. Mock the TextureLoader:

JAVASCRIPTCopied
jest.mock('three', () => {
  const actualThree = jest.requireActual('three');
  return {
    ...actualThree,
    TextureLoader: jest.fn().mockImplementation(() => {
      return {
        load: (url) => {
          const texture = new actualThree.Texture();
          // Set necessary properties
          return texture;
        }
      };
    })
  };
});

Alternative Testing Approaches

1. Use a headless browser: Consider using Puppeteer or Playwright instead of jsdom for tests that require actual loading.

2. Component isolation: Test components that use loaded assets separately from the loading logic.

3. Integration tests: For full integration tests, consider using a real browser environment.

These approaches should help you work around the limitations of testing Three.js loaders in a non-browser environment like jsdom with Vitest.