Implementing Testing Conventions in JavaScript Development

---
description: Enforce standardized testing conventions in JavaScript development to ensure robust and reliable code.
globs: ["**/*.js", "**/*.jsx", "**/*.ts", "**/*.tsx"]
tags: [javascript, testing, best-practices]
priority: 1
version: 1.0.0
---

# Implementing Testing Conventions in JavaScript Development

## Context
- Applicable to all JavaScript and TypeScript projects.
- Ensures consistency and reliability in test code across the codebase.

## Requirements
- **Test Structure**: Organize tests using the `describe` and `it` functions to clearly define test suites and individual test cases.
- **Test Naming**: Use descriptive and clear names for test cases to convey their purpose effectively.
- **Avoid Overuse of Hooks**: Limit the use of `beforeAll`, `beforeEach`, `afterAll`, and `afterEach` hooks to maintain test clarity and prevent complexity. ([blog.logrocket.com](https://blog.logrocket.com/javascript-testing-best-practices/?utm_source=openai))
- **Mocking**: Mock external dependencies and modules to isolate the unit under test, but avoid excessive mocking to ensure tests remain meaningful. ([genqe.ai](https://genqe.ai/ai-blogs/2025/02/22/13-javascript-testing-best-practices-you-should-know-2025/?utm_source=openai))
- **Assertions**: Utilize a variety of assertions to validate different aspects of the code's behavior.
- **Error Handling**: Test both expected and unexpected scenarios, including edge cases and error conditions.
- **Code Coverage**: Aim for a high percentage of code coverage, ensuring that all critical paths are tested.
- **Continuous Integration**: Integrate tests into the CI/CD pipeline to automatically run tests on new commits and pull requests.

## Examples

// Good: Organized test suite with clear structure and descriptive names
describe('User Authentication Module', () => {
  describe('Login Functionality', () => {
    it('should authenticate user with valid credentials', () => {
      // Test implementation
    });

    it('should reject user with invalid credentials', () => {
      // Test implementation
    });
  });

  describe('Registration Functionality', () => {
    it('should register user with valid data', () => {
      // Test implementation
    });

    it('should not register user with missing fields', () => {
      // Test implementation
    });
  });
});
// Bad: Overuse of hooks leading to complex and hard-to-follow tests
describe('User Service', () => {
  beforeAll(() => {
    // Setup code
  });

  beforeEach(() => {
    // Setup code
  });

  afterEach(() => {
    // Teardown code
  });

  afterAll(() => {
    // Teardown code
  });

  it('should create a new user', () => {
    // Test implementation
  });

  it('should delete a user', () => {
    // Test implementation
  });
});