gen-tests

Generate Tests

Generate comprehensive tests for the JavaScript/TypeScript codebase, including unit tests (Vitest) and end-to-end browser tests (Playwright).

Step 1: Analyze Existing Test Coverage

1. Check if tests exist:

   npm test -- --coverage 2>/dev/null || echo "No tests found or coverage not configured"
   

2. If using Vitest with coverage:

   npx vitest run --coverage
   

3. Identify untested or under-tested modules by reviewing the coverage report.

Step 2: Generate Unit Tests (Vitest)

For each module or function lacking coverage:

1. Analyze the code - understand inputs, outputs, side effects, and edge cases

2. Create test file - follow the naming convention <module>.test.ts or __tests__/<module>.test.ts

3. Write tests covering:

   • Happy path scenarios
   • Edge cases (empty inputs, boundary values, null/undefined handling)
   • Error conditions and exception handling
   • Mocked external dependencies (APIs, stores)

4. Use test utilities for common setup in test helpers

Example test structure:

import { describe, it, expect, vi, beforeEach } from 'vitest';
import { functionUnderTest } from './module';

describe('functionUnderTest', () => {
  beforeEach(() => {
    vi.clearAllMocks();
  });

  it('should return expected result for valid input', () => {
    const result = functionUnderTest('valid');
    expect(result).toBe('expected');
  });

  it('should throw error for invalid input', () => {
    expect(() => functionUnderTest(null)).toThrow();
  });
});

1. Run and verify:

   npx vitest run <test-file>
   

Step 3: Generate E2E Browser Tests (Playwright)

If the project has web routes/UI components:

1. Create E2E test directory: tests/e2e/

2. Write E2E tests in tests/e2e/<feature>.spec.ts:

   • Test critical user flows (navigation, form submissions)
   • Test UI state changes and interactions
   • Test API responses via the browser
   • Use page.goto(), page.click(), page.fill(), expect() assertions