testing

Testing Guidelines

When writing tests for this project:

Test Structure

Use table-driven tests for utilities and pure functions:

describe('formatCurrency', () => {
  const testCases = [
    { input: 100, expected: '$1.00', description: 'whole dollars' },
    { input: 99, expected: '$0.99', description: 'cents only' },
    { input: 0, expected: '$0.00', description: 'zero' },
    { input: -100, expected: '-$1.00', description: 'negative' },
  ];

  testCases.forEach(({ input, expected, description }) => {
    it(`handles ${description}`, () => {
      expect(formatCurrency(input)).toBe(expected);
    });
  });
});

Coverage Requirements

• Minimum 80% coverage for new code
• 100% coverage for utility functions
• Integration tests for all API endpoints

Mocking

// Use vi.mock for module mocking
vi.mock('@/services/api', () => ({
  api: {
    users: {
      get: vi.fn(),
    },
  },
}));

// Use MSW for API mocking in integration tests
import { rest } from 'msw';
import { server } from '@/tests/server';

server.use(
  rest.get('/api/users/:id', (req, res, ctx) => {
    return res(ctx.json({ id: req.params.id, name: 'Test User' }));
  })
);

Naming Conventions

• Test files: *.test.ts or *.spec.ts
• Test descriptions: Start with verb ("renders", "returns", "throws")
• Use describe blocks to group related tests

Reference Implementation

See @src/utils/tests/formatters.test.ts for examples.