JavaScript Testing 4

Question 1

What is the purpose of `beforeEach` in a Jest or Mocha test suite?

Accepted Answer

Runs before each individual test in a describe block

Answer

beforeEach runs a setup function before every individual test (it/test) in its enclosing describe block.

Question 2

Which tool is commonly used for end-to-end testing of JavaScript web applications by automating a real browser?

Accepted Answer

Playwright

Answer

Playwright by Microsoft automates real browsers (Chromium, Firefox, WebKit) for end-to-end testing of web applications.

Question 3

What does `jest.useFakeTimers()` allow you to do?

Accepted Answer

Control setTimeout/setInterval manually without waiting real time

Answer

jest.useFakeTimers() replaces timer functions so you can advance time programmatically using jest.advanceTimersByTime().

Question 4

In testing, what is a 'test fixture'?

Accepted Answer

A fixed set of preconditions or data used to set up tests

Answer

A test fixture is known data or state set up before tests run to ensure consistent, reproducible test conditions.

Question 5

How does React Testing Library differ from Enzyme in its testing philosophy?

Accepted Answer

RTL focuses on user behavior and DOM queries; Enzyme on component internals

Answer

React Testing Library encourages testing from the user's perspective using DOM queries, while Enzyme allows testing internal component state and methods.

JavaScript Practice Test

JavaScript Practice Test

JavaScript Testing 4