Test isolation strategies in Cypress - Practice Problems & Coding Challenges

Challenge - 5 Problems

🧠 Conceptual

intermediate

Why is test isolation important in Cypress?

In Cypress testing, why do we need to isolate tests from each other?

A To prevent Cypress from opening multiple browser windows

B To make tests run slower and use more resources

C To allow tests to share data and speed up execution

D To ensure tests do not depend on each other's state and results are reliable

💡 Hint

Think about what happens if one test changes something that affects another test.

Test isolation ensures each test runs independently without side effects from others, making results consistent and trustworthy.

❓ Predict Output

intermediate

What is the output of this Cypress test suite?

Consider this Cypress test code. What will be the value of count after all tests run?

Cypress

let count = 0;
describe('Counter tests', () => {
  beforeEach(() => {
    count = 0;
  });
  it('increments count', () => {
    count += 1;
    expect(count).to.equal(1);
  });
  it('increments count again', () => {
    count += 1;
    expect(count).to.equal(1);
  });
});

// What is the final value of count?

A 2

B 0

C 1

D Undefined

💡 Hint

Look at what beforeEach does before each test.

The beforeEach resets count to 0 before each test. Each test increments it to 1. After all tests, count remains 1.

❓ assertion

advanced

Which assertion best verifies test isolation of localStorage?

You want to confirm that localStorage is cleared between tests in Cypress. Which assertion correctly checks this?

A expect(localStorage.getItem('token')).to.equal('token');

B expect(localStorage.getItem('token')).to.be.null;

C expect(localStorage.length).to.be.greaterThan(0);

D expect(localStorage.token).to.equal('');

💡 Hint

Think about what value localStorage returns when a key does not exist.

If localStorage is cleared, getItem returns null for any key. Checking for null confirms isolation.

🔧 Debug

advanced

Identify the test isolation issue in this Cypress code

Look at this Cypress test code. What causes the tests to fail intermittently due to poor isolation?

Cypress

let sharedData = [];
describe('Shared data tests', () => {
  it('adds item', () => {
    sharedData.push('item1');
    expect(sharedData).to.include('item1');
  });
  it('checks empty array', () => {
    expect(sharedData).to.be.empty;
  });
});

A sharedData is not reset between tests, causing state leakage

B The expect syntax is incorrect and causes errors

C Cypress does not support arrays in tests

D Tests run in parallel causing race conditions

💡 Hint

Check if sharedData is cleared before each test.

sharedData is declared outside tests and not reset, so the second test sees data from the first, breaking isolation.

❓ framework

expert

Which Cypress command best ensures test isolation by resetting application state?

In Cypress, which command is best used to reset the application state between tests to ensure isolation?

A cy.visit('/')

B cy.resetAppState()

C cy.reload()

D cy.clearCookies()

💡 Hint

Think about how to start fresh with a clean page load.

cy.visit('/') reloads the app from the start URL, resetting state including cookies, localStorage, and UI.