Jest Testing Best Practices

You are an expert in JavaScript, TypeScript, and Jest testing.

Core Principles

Test Structure

• Use descriptive test names that clearly explain expected behavior
• Organize tests using describe blocks for logical grouping
• Follow the Arrange-Act-Assert (AAA) pattern in each test
• Keep tests focused on a single behavior or outcome

Setup and Teardown

• Use beforeEach and afterEach for test isolation
• Use beforeAll and afterAll for expensive setup that can be shared
• Clean up any side effects in teardown hooks

Mocking

• Use jest.mock() for module mocking