---
Description: Rules to help Cursor write unit tests code that aligns with the project's standards
globs: *.test.js,*.test.ts
alwaysApply: false
---
# Project Rules

## Jest Unit Testing

In Jest unit test files, **never perform mocking globally**. Instead, perform all mocks inside the `beforeEach()` section.

### Rationale
- Keeps test setup centralized and visible
- Ensures mocks are reset between tests
- Makes test dependencies explicit
- Prevents test pollution from global mocks

### Example

❌ **Don't do this:**
```javascript
const mockSleep = jest.fn().mockResolvedValue(undefined);
jest.mock('../../../../utils/sleep', () => mockSleep);

describe('MyClass', () => {
  // ...
});
```

✅ **Do this instead:**
```javascript
describe('MyClass', () => {
  let mockSleep;

  beforeEach(() => {
    jest.mock('../../../../utils/sleep');
    mockSleep = require('../../../../utils/sleep');
    mockSleep.mockResolvedValue(undefined);

// ... other setup
  });
});
```

Alternatively, in cases where jest.mock() doesn't work well out of the box, this can be performed too:

```javascript
  beforeEach(() => {
    jest.mock('../../../../utils/sleep', () => jest.fn().mockResolvedValue(undefined));
    mockSleep = require('../../../../utils/sleep');
  });

  // Or if the sleep js module actually exports an object:
  beforeEach(() => {
    jest.mock('../../../../utils/sleep', () => ({
      sleep: jest.fn().mockResolvedValue(undefined),
    }));
    mockSleep = require('../../../../utils/sleep');
  });
```

Note: `jest.mock()` must still be called at the module level (for hoisting), but all mock configuration should happen in `beforeEach()`.