250+ React Js MCQ With Online Practice Test

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React.js, often simply called React, is a highly popular JavaScript library for building user interfaces. Developed and maintained by Facebook, React is renowned for its component-based architecture and the ability to efficiently update and render components when data changes. It is a foundational tool for developing modern web and mobile applications, allowing developers to create dynamic and interactive user interfaces with ease. React's vast ecosystem, including tools like React Native for mobile app development, makes it a top choice for frontend development and a key player in the world of web technologies.

161. What is the primary purpose of testing React applications?

Answer: To ensure that the app works as expected

162. Which testing library is commonly used for unit testing React components?

Answer: React Testing Library

163. In React, what is the role of a test runner?

Answer: It executes test suites

164. What is a unit test in the context of React testing?

Answer: A test that checks a single unit of code

165. Which testing library provides utilities for querying and interacting with React components in tests?

Answer: React Testing Library

166. In React testing, what is the purpose of a "snapshot test"?

Answer: To compare the rendered output

167. What does the term "mocking" refer to in React testing?

Answer: Simulating the behavior of dependencies

168. In React, what is the purpose of a "test suite"?

Answer: A collection of test cases

169. What is the recommended approach for structuring tests in a React application?

Answer: By organizing tests based on file structure

170. In React, what is a "test double" or "mock"?

Answer: A fake implementation of a dependency
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