unit-testing-framework
Write comprehensive unit tests with high coverage using testing frameworks like Jest, pytest, JUnit, or RSpec. Use when writing tests for functions, classes, components, or establishing testing standards.
What this skill does
# Unit Testing Framework
## Table of Contents
- [Overview](#overview)
- [When to Use](#when-to-use)
- [Quick Start](#quick-start)
- [Reference Guides](#reference-guides)
- [Best Practices](#best-practices)
## Overview
Write effective unit tests that are fast, isolated, readable, and maintainable following industry best practices and AAA (Arrange-Act-Assert) pattern.
## When to Use
- Writing tests for new code
- Improving test coverage
- Establishing testing standards
- Refactoring with test safety
- Implementing TDD (Test-Driven Development)
- Creating test utilities and mocks
## Quick Start
Minimal working example:
```javascript
// Jest/JavaScript example
describe("UserService", () => {
describe("createUser", () => {
it("should create user with valid data", async () => {
// Arrange - Set up test data and dependencies
const userData = {
email: "[email protected]",
firstName: "John",
lastName: "Doe",
};
const mockDatabase = createMockDatabase();
const service = new UserService(mockDatabase);
// Act - Execute the function being tested
const result = await service.createUser(userData);
// Assert - Verify the outcome
expect(result.id).toBeDefined();
expect(result.email).toBe("[email protected]");
expect(mockDatabase.save).toHaveBeenCalledWith(
expect.objectContaining(userData),
);
});
});
});
```
## Reference Guides
Detailed implementations in the `references/` directory:
| Guide | Contents |
|---|---|
| [Test Structure (AAA Pattern)](references/test-structure-aaa-pattern.md) | Test Structure (AAA Pattern) |
| [Test Cases by Language](references/test-cases-by-language.md) | Test Cases by Language |
| [Mocking & Test Doubles](references/mocking-test-doubles.md) | Mocking & Test Doubles |
| [Testing Async Code](references/testing-async-code.md) | Testing Async Code, Test Coverage |
| [Testing Edge Cases](references/testing-edge-cases.md) | Testing Edge Cases |
| [Example: Complete Test Suite](references/example-complete-test-suite.md) | import { UserService } from "./user-service"; |
## Best Practices
### ✅ DO
- Write tests before or alongside code (TDD)
- Test one thing per test
- Use descriptive test names
- Follow AAA pattern
- Test edge cases and error conditions
- Keep tests isolated and independent
- Use setup/teardown appropriately
- Mock external dependencies
- Aim for high coverage on critical paths
- Make tests fast (< 10ms each)
- Use parameterized tests for similar cases
- Test public interfaces, not implementation
### ❌ DON'T
- Test implementation details
- Write tests that depend on each other
- Ignore failing tests
- Test third-party library code
- Use real databases/APIs in unit tests
- Make tests too complex
- Skip edge cases
- Forget to clean up resources
- Test everything (focus on business logic)
- Write flaky tests
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