AgentSkillsCN

test-driven-development

在代码实现之前先编写测试用例。当您需要启动新功能或修复 Bug 时，可选用此技能。涵盖红-绿-重构的循环，以及 TDD 的最佳实践。

SKILL.md
--- frontmatter
name: test-driven-development
description: Write tests before implementation code. Use when starting new features or fixing bugs. Covers Red-Green-Refactor cycle and TDD best practices.
allowed-tools: Read, Write, Edit, Bash, Glob, Grep

Test-Driven Development

The TDD Cycle

  1. •Red: Write a failing test
  2. •Green: Write minimal code to pass
  3. •Refactor: Improve code while keeping tests green

Workflows

  • • Write Test: Write a test that describes desired behavior
  • • Run Test: Verify it fails (Red)
  • • Implement: Write minimal code to pass
  • • Run Test: Verify it passes (Green)
  • • Refactor: Clean up while tests stay green
  • • Repeat: Next test case

TDD Example

Step 1: Red - Write Failing Test

typescript
describe("Calculator", () => {
  test("adds two numbers", () => {
    const calc = new Calculator();
    expect(calc.add(2, 3)).toBe(5);
  });
});

// Run: FAIL - Calculator is not defined

Step 2: Green - Minimal Implementation

typescript
class Calculator {
  add(a: number, b: number): number {
    return a + b;
  }
}

// Run: PASS

Step 3: Refactor (if needed)

Code is already clean, move to next test.

Step 4: Next Test

typescript
test("subtracts two numbers", () => {
  const calc = new Calculator();
  expect(calc.subtract(5, 3)).toBe(2);
});

// Run: FAIL - subtract is not defined

TDD Benefits

  • •Design Feedback: Tests reveal design issues early
  • •Documentation: Tests document expected behavior
  • •Confidence: Refactor fearlessly with test safety net
  • •Focus: One behavior at a time

TDD Tips

  1. •Start Simple: Begin with the simplest test case
  2. •One Assert: Each test should verify one behavior
  3. •Descriptive Names: Test names are documentation
  4. •No Logic in Tests: Tests should be obvious
  5. •Fast Feedback: Tests should run in milliseconds

When to Use TDD

  • •New features with clear requirements
  • •Bug fixes (write failing test first)
  • •Complex business logic
  • •API contract development

When TDD is Less Useful

  • •Exploratory/prototype code
  • •UI layout changes
  • •Simple CRUD operations