This presentation is about testing in React applications. Test-driven development approach for small applications or for the enterprise. Coverage and threshold. Tests components before implementation. How properly mock data or static configs, testing GraphQL integration, best practices, and scalable solutions. In the presentation, we going to see how Test-driven development is uncomfortable in the beginning and how big the benefit of tests is in the end. We going to test components with Apollo Client and hooks. In general, this presentation will cover almost all aspects of TDD in React Applications.