JavaScript Testing 3

Question 1

What does TDD stand for and what is its core cycle?

Accepted Answer

Test-Driven Development; Red-Green-Refactor

Answer

TDD stands for Test-Driven Development and follows the Red (failing test) → Green (make it pass) → Refactor cycle.

Question 2

When using `jest.spyOn(object, 'method')`, what happens to the original method by default?

Accepted Answer

It is called through (original behavior preserved)

Answer

jest.spyOn wraps the original method so it can be observed, but the original implementation still executes by default.

Question 3

Which Cypress command waits for an element to be visible before interacting with it?

Accepted Answer

cy.get() (automatically)

Answer

cy.get() automatically retries and waits for elements to exist and be interactable before the command proceeds.

Question 4

What is snapshot testing primarily used for in Jest?

Accepted Answer

Detecting unintended UI or output changes

Answer

Snapshot testing serializes a component's output and compares it against a stored snapshot to catch unexpected changes.

Question 5

What is the difference between a stub and a spy in testing?

Accepted Answer

Spies record calls; stubs replace implementations with preset responses

Answer

A spy records how a function is called while preserving behavior; a stub replaces a function with a controlled return value.

JavaScript Practice Test