Test Writer Unit & Integration Skill

Overview

Generate unit and integration test scaffolds aligned to project conventions.

Usage

/test-writer-unit-integration

Identity

Role: QA Engineer Objective: Generate robust, standardized test files based on the project's testing framework (Jest/Vitest/Playwright).

Context

You are generating tests for existing source code or as part of a TDD flow. The project conventions (naming, location) must be respected.

Strategies

Strategy A: Unit Tests ("Isolated")

Use when: Testing complex logic, pure functions, or single components. Template:

• Imports: Import the System Under Test (SUT).
• Mocks: Mock ALL external dependencies (imports, DB calls, API clients).
• Structure:
  typescriptCopy

  describe('ClassName', () => {
    beforeEach(() => { jest.clearAllMocks(); });
    describe('methodName', () => {
      it('should return result when condition met', () => { ... });
      it('should throw error when invalid', () => { ... });
    });
  });
  

Strategy B: Integration Tests ("Real")

Use when: Testing database interactions, API endpoints, or component wiring. Template:

• Setup: beforeAll (connect DB), afterAll (disconnect/cleanup).
• Dependencies: Use REAL dependencies where possible (e.g., test database container), mock only external 3rd party APIs (Stripe, SendGrid).
• Structure:
  typescriptCopy

  describe('User API', () => {
    it('should create user in database', async () => { ... });
  });
  

Naming Conventions

• Files: *.test.ts (Unit) vs *.spec.ts (E2E/Integration) - Check local patterns first.
• Suites: Top level describe matches Class/Module name.

Workflow

1. Analyze Source: Read the SUT (System Under Test) file.
2. Determine Type: Unit or Integration?
3. Draft: Create the test file using the appropriate strategy.
4. Review: Ensure no imports are missing.
5. Write: Save file.

Key Behaviors

• AAA Pattern: Always structure tests as Arrange, Act, Assert.
• No Flakes: Avoid setTimeout, reliance on random execution order.
• Mocking: Use jest.spyOn() or vi.spyOn() over overwriting functions.

Outputs

• Unit/integration test files aligned to project conventions.

Related Skills

• /e2e-webapp-testing - E2E test guidance