Testing - Coverage & Quick Reference

Related Guides

• Testing (Unit & E2E) — Test templates and examples
• Testing - Mocking & Configuration — Mock factories, Jest config, and best practices

Coverage Reports

Generate Coverage

# Generate coverage report
npm run test:cov

# View coverage in browser
open coverage/lcov-report/index.html

Coverage Goals

• Statements: > 80%
• Branches: > 75%
• Functions: > 80%
• Lines: > 80%

What to Exclude from Coverage

collectCoverageFrom: [
    'src/**/*.(t|j)s',
    '!src/main.ts',           // Bootstrap file
    '!src/**/*.module.ts',    // Module definitions
    '!src/**/*.dto.ts',       // Data transfer objects
    '!src/**/*.entity.ts',    // Database entities
    '!src/**/*.enum.ts',      // Enums
    '!src/**/*.interface.ts', // Type definitions
],

---

Summary Checklist

Before submitting tests, verify:

Unit Tests:

• Mock service layer using factory from test/mocks/
• Test all controller methods (create, update, findOne, findAll, delete)
• Test both success and error cases
• Verify service methods are called with correct arguments
• Clear mocks in afterEach

E2E Tests:

• Test full HTTP request/response pipeline
• Verify routing works correctly
• Test ValidationPipe (400 for invalid DTOs)
• Test TransformInterceptor (JSON:API response format)
• Test AllExceptionsFilter (error responses)
• Verify response.body structure matches JSON:API spec
• Close app in afterAll

General:

• Tests follow AAA pattern (Arrange, Act, Assert)
• Test names are descriptive
• Each test focuses on one thing
• Coverage meets minimum thresholds (>80%)
• All tests pass locally before pushing

---

Quick Reference

Supertest Request Methods

// GET request
await request(server).get('/engagements/123/orders').expect(200);

// POST request with body
await request(server).post('/engagements/123/orders').send(createDTO).expect(201);

// PATCH request
await request(server).patch('/engagements/123/orders/456').send(updateDTO).expect(200);

// DELETE request
await request(server).delete('/engagements/123/orders/456').expect(204);

// With query parameters
await request(server).get('/engagements/123/orders').query({ page: 1, limit: 10 }).expect(200);

// Check response body
const response = await request(server).get('/engagements/123/orders/456').expect(200);
expect(response.body.data.id).toBe('456');

Common Mock Patterns

// Mock successful response
mockService.findOne.mockResolvedValue(mockEntity);

// Mock error
mockService.findOne.mockRejectedValue(new NotFoundException());

// Mock different return values for multiple calls
mockService.findOne
    .mockResolvedValueOnce({ id: '1' })
    .mockResolvedValueOnce({ id: '2' })
    .mockResolvedValueOnce({ id: '3' });

// Mock with custom logic
mockService.findOne.mockImplementation(async (id: string) => {
    if (id === 'valid-id') {
        return { id, name: 'Test' };
    }
    throw new NotFoundException();
});

JSON:API Response Assertions

// Single resource
expect(response.body).toEqual(
    expect.objectContaining({
        data: expect.objectContaining({
            type: 'engagement-orders',
            id: expect.any(String),
            attributes: expect.objectContaining({
                order_type: 'LAB',
            }),
        }),
        status: expect.objectContaining({ code: 200000 }),
        links: expect.objectContaining({ self: expect.any(String) }),
    }),
);

// Paginated collection
expect(response.body).toEqual(
    expect.objectContaining({
        data: expect.any(Array),
        meta: expect.objectContaining({
            pagination: expect.objectContaining({
                page: 1,
                page_size: 10,
                total: expect.any(Number),
                total_pages: expect.any(Number),
            }),
        }),
        links: expect.objectContaining({
            self: expect.any(String),
            first: expect.any(String),
            last: expect.any(String),
        }),
    }),
);

---

File Structure Reference

Standard locations for test artifacts within a bounded context:

apps/[service-name]/
├── jest.config.js                              # Unit test Jest configuration
├── test/
│   ├── jest-e2e.json                           # E2E test Jest configuration
│   ├── mocks/
│   │   └── mock-[entity-name].ts               # Mock factory (service + entity + DTO)
│   ├── unit/
│   │   ├── [entity-name].controller.spec.ts    # Controller unit tests
│   │   └── [entity-name].service.spec.ts       # Service unit tests
│   └── e2e/
│       └── [entity-name].e2e-spec.ts           # E2E tests
└── ...
libs/
└── common/
    └── src/
        └── testing/
            └── test-setup.ts                   # createTestApp + createTestingModule helpers