Testing React Components Quiz

Question 1

What is the guiding principle of React Testing Library?

Accepted Answer

The more your tests resemble how the software is used, the more confidence they give

Answer

Test every function in isolation

Answer

Aim for 100 percent coverage

Answer

Test internal state to catch bugs early

Question 2

Which of these is testing implementation rather than behaviour?

Accepted Answer

Asserting the component's internal isOpen state is true

Answer

Asserting a button with a given name is on screen

Answer

Asserting a click reveals a listbox

Answer

Asserting an error message appears

Question 3

Which query should you prefer first?

Accepted Answer

getByRole

Answer

getByTestId

Answer

getByText

Answer

container.querySelector

Question 4

Which query should you use to assert an element is NOT present?

Accepted Answer

queryBy

Answer

getBy

Answer

findBy

Answer

getAllBy

Question 5

Which query do you use for an element that appears after an async update?

Accepted Answer

findBy

Answer

getBy

Answer

queryBy

Answer

getAllBy

Question 6

Why prefer user-event over fireEvent?

Accepted Answer

It simulates the full sequence of events a real interaction produces, rather than one raw event

Answer

It is faster

Answer

fireEvent is deprecated

Answer

It does not require await

Question 7

What does an 'update was not wrapped in act(...)' warning usually mean?

Accepted Answer

A state update happened after the test finished, usually an unawaited async operation

Answer

You must wrap every render in act

Answer

The component has too many hooks

Answer

React Testing Library is misconfigured

Question 8

Why mock with Mock Service Worker rather than replacing fetch?

Accepted Answer

It intercepts at the network level, so the component exercises its real data fetching code

Answer

It runs faster

Answer

It requires no setup

Answer

fetch cannot be mocked