jest

To write unit tests for JavaScript and TypeScript, you configure the test environment using `jest.config.ts` and `jest.setup.ts`, then define test cases with basic structures, common matchers, and mocking techniques to validate application logic.

The best way to test React components with Jest is by using the `@testing-library/react` package, which enables interactive component testing by simulating user interactions and verifying rendered output within your test suite.

Snapshot testing captures the rendered output of UI components or data structures into a saved file, allowing Jest to automatically compare future test runs against the baseline to detect unexpected visual or structural changes.

Yes, you can mock dependencies and test asynchronous operations in Jest using built-in mocking functions and async/await syntax, ensuring that external API calls and complex data flows are properly validated.

You generate code coverage reports by configuring Jest to track executed lines of code during test runs, producing a detailed analysis that shows untested branches, functions, and statements in your application.