javascript-testing

To set up Vitest for JavaScript testing, create a `vitest.config.ts` file to configure the environment, then write unit and integration tests using the provided framework strategies. This enables fast test execution and optimal coverage reporting.

Mocking modules and dependencies in Jest and Vitest is achieved through module mocking, global mocks, and dependency injection. These techniques isolate the code under test, ensuring unit tests evaluate pure functions and classes without external side effects.

Testing React components and custom hooks with Testing Library involves rendering UI elements and asserting on user interactions. This approach validates component behavior and hook state changes under various conditions without relying on internal implementation details.

Yes, TDD workflows can handle asynchronous code, promise handling, and timer manipulation in JavaScript testing. By configuring fake timers and awaiting promises within Vitest or Jest, you control async execution and ensure reliable test outcomes.

Vitest provides compatibility with Jest's mocking API and fixture patterns, allowing you to transition JavaScript testing setups smoothly. You can reuse test fixtures and module mocking strategies while leveraging Vitest's faster execution environment.

Missing test coverage for asynchronous operations occurs when promises are not properly awaited or timer manipulation is not correctly flushed. Implementing explicit async assertions and ensuring all promise resolutions complete during testing resolves these coverage gaps.