backend-testing

Backend Testing

When to use this skill

Specific situations that should trigger this skill:

• New feature development: Write tests first using TDD (Test-Driven Development)
• Adding API endpoints: Test success and failure cases for REST APIs
• Bug fixes: Add tests to prevent regressions
• Before refactoring: Write tests that guarantee existing behavior
• CI/CD setup: Build automated test pipelines

Input Format

Format and required/optional information to collect from the user:

Required information

• Framework: Express, Django, FastAPI, Spring Boot, etc.
• Test tool: Jest, Pytest, Mocha/Chai, JUnit, etc.
• Test target: API endpoints, business logic, DB operations, etc.

Optional information

• Database: PostgreSQL, MySQL, MongoDB (default: in-memory DB)
• Mocking library: jest.mock, sinon, unittest.mock (default: framework built-in)
• Coverage target: 80%, 90%, etc. (default: 80%)
• E2E tool: Supertest, TestClient, RestAssured (optional)

Input example

Test the user authentication endpoints for an Express.js API:
- Framework: Express + TypeScript
- Test tool: Jest + Supertest
- Target: POST /auth/register, POST /auth/login
- DB: PostgreSQL (in-memory for tests)
- Coverage: 90% or above

Instructions

Step-by-step task order to follow precisely.

Step 1: Set up the test environment

Install and configure the test framework and tools.

Tasks:

• Install test libraries
• Configure test database (in-memory or separate DB)
• Separate environment variables (.env.test)
• Configure jest.config.js or pytest.ini

Example (Node.js + Jest + Supertest):

npm install --save-dev jest ts-jest @types/jest supertest @types/supertest

jest.config.js:

module.exports = {
  preset: 'ts-jest',
  testEnvironment: 'node',
  roots: ['<rootDir>/src'],
  testMatch: ['**/__tests__/**/*.test.ts'],
  collectCoverageFrom: [
    'src/**/*.ts',
    '!src/**/*.d.ts',
    '!src/__tests__/**'
  ],
  coverageThreshold: {
    global: {
      branches: 80,
      functions: 80,
      lines: 80,
      statements: 80
    }
  },
  setupFilesAfterEnv: ['<rootDir>/src/__tests__/setup.ts']
};