Test isolation strategies in Cypress - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to clear cookies before each test to ensure test isolation.

Cypress

beforeEach(() => { cy.[1]() })

Drag options to blanks, or click blank then click option'

AclearCookies

BclearCookiesAndLocalStorage

CclearCookie

DclearAllCookies

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'clearCookie' which clears only one cookie instead of all.

Using non-existent commands like 'clearAllCookies'.

The cy.clearCookie() command clears a specific cookie, but to clear all cookies, cy.clearCookies() is used. Since the blank expects the exact command to clear cookies before each test, clearCookies is the correct choice.

2fill in blank

medium

Complete the code to reset the database state before each test using a custom Cypress task.

Cypress

beforeEach(() => { cy.task('[1]') })

Drag options to blanks, or click blank then click option'

AclearDb

BcleanDatabase

CresetDb

DresetDatabase

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect task names that are not defined in Cypress plugins.

Confusing task names with commands.

The custom Cypress task to reset the database is often named resetDb. This task is called before each test to ensure a clean database state, which is essential for test isolation.

3fill in blank

hard

Fix the error in the code to properly isolate tests by clearing local storage before each test.

Cypress

beforeEach(() => { cy.[1]() })

Drag options to blanks, or click blank then click option'

AclearLocalStorageItem

BclearLocalStorages

CclearLocalStorageCache

DclearLocalStorage

Attempts:

3 left

💡 Hint

Common Mistakes

Using plural or incorrect command names that do not exist.

Trying to clear local storage with commands meant for cookies.

The correct Cypress command to clear local storage is cy.clearLocalStorage(). Other options are invalid commands and will cause errors.

4fill in blank

hard

Fill both blanks to isolate tests by resetting the server state and clearing cookies before each test.

Cypress

beforeEach(() => { cy.task('[1]'); cy.[2]() })

Drag options to blanks, or click blank then click option'

AresetDb

BclearCookie

CclearCookies

DresetServer

Attempts:

3 left

💡 Hint

Common Mistakes

Using clearCookie which clears only one cookie.

Using undefined tasks like resetServer.

To isolate tests, we reset the database state with the resetDb task and clear all cookies with cy.clearCookies() before each test.

5fill in blank

hard

Fill all three blanks to create a test isolation setup that resets the database, clears local storage, and clears cookies before each test.

Cypress

beforeEach(() => { cy.task('[1]'); cy.[2](); cy.[3]() })

Drag options to blanks, or click blank then click option'

AresetDb

BclearLocalStorage

CclearCookies

DresetServer

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect or undefined commands for clearing storage.

Mixing up the order of commands.

This setup ensures test isolation by resetting the database with resetDb, clearing local storage with clearLocalStorage(), and clearing all cookies with clearCookies() before each test.

Practice

1. What is the main purpose of test isolation in Cypress testing?

easy

A. To speed up test execution by running all tests together

B. To share data between tests for faster setup

C. To keep tests independent and avoid interference between them

D. To reduce the number of tests needed

Solution

1. Step 1: Understand test isolation concept

   Test isolation means each test runs independently without relying on others.

2. Step 2: Identify the main benefit

   This independence avoids interference and makes tests reliable and easier to debug.

3. Final Answer:

   To keep tests independent and avoid interference between them -> Option C

4. Quick Check:

   Test isolation = Independent tests [OK]

Hint: Test isolation means no test depends on another [OK]

Common Mistakes:

• Thinking tests should share data to run faster
• Believing test isolation reduces total tests
• Confusing isolation with parallel execution

2. Which Cypress hook is best used to reset application state before each test to ensure isolation?

easy

A. beforeEach

B. before

C. after

D. afterEach

Solution

1. Step 1: Recall Cypress hooks purpose

   beforeEach runs before every test, ideal for resetting state.

2. Step 2: Compare with other hooks

   before runs once before all tests, after and afterEach run after tests, so they don't reset state before tests.

3. Final Answer:

   beforeEach -> Option A

4. Quick Check:

   Reset state before each test = beforeEach [OK]

Hint: Use beforeEach to reset state before every test [OK]

Common Mistakes:

• Using before which runs only once
• Confusing afterEach with beforeEach
• Not resetting state at all

3. Consider this Cypress test code snippet:

describe('My Tests', () => {
  beforeEach(() => {
    cy.visit('/login')
  })

  it('Test A', () => {
    cy.get('#username').type('user1')
    cy.get('#password').type('pass1')
    cy.get('button').click()
    cy.url().should('include', '/dashboard')
  })

  it('Test B', () => {
    cy.get('#username').type('user2')
    cy.get('#password').type('pass2')
    cy.get('button').click()
    cy.url().should('include', '/dashboard')
  })
})

What is the main benefit of using beforeEach here?

medium

A. It visits the login page once before all tests

B. It visits the login page before each test to isolate them

C. It skips the login page for Test B

D. It runs tests faster by sharing the login page

Solution

1. Step 1: Analyze beforeEach usage

   beforeEach runs before every test, so it visits the login page before Test A and Test B.

2. Step 2: Understand test isolation effect

   This ensures each test starts fresh on the login page, isolating tests and avoiding state carryover.

3. Final Answer:

   It visits the login page before each test to isolate them -> Option B

4. Quick Check:

   beforeEach = fresh start per test [OK]

Hint: beforeEach runs before every test, isolating them [OK]

Common Mistakes:

• Thinking beforeEach runs only once
• Assuming tests share the same page state
• Believing it skips steps for some tests

4. You wrote tests with beforeEach to reset state, but tests still fail due to shared data. What is the likely mistake?

medium

A. Using before instead of beforeEach

B. Not visiting the page in any hook

C. Using afterEach to reset state

D. Running tests in parallel

Solution

1. Step 1: Identify hook usage problem

   If before is used, it runs once before all tests, so state is not reset before each test.

2. Step 2: Understand impact on test isolation

   This causes shared data between tests, breaking isolation and causing failures.

3. Final Answer:

   Using before instead of beforeEach -> Option A

4. Quick Check:

   beforeEach resets state per test, before does not [OK]

Hint: Use beforeEach, not before, to reset state each test [OK]

Common Mistakes:

• Confusing before and beforeEach hooks
• Assuming afterEach resets state before tests
• Ignoring test parallelism effects

5. You want to run Cypress tests in parallel on CI to speed up testing. Which test isolation strategy helps ensure tests run reliably in parallel?

hard

A. Sharing global variables between tests

B. Running all tests in a single browser session without reset

C. Disabling test retries to avoid repeated runs

D. Using beforeEach to reset state and avoid shared data

Solution

1. Step 1: Understand parallel test challenges

   Parallel tests run simultaneously, so shared state causes flaky failures.

2. Step 2: Identify isolation strategy for parallel runs

   Using beforeEach to reset state and avoid shared data ensures each test is independent and reliable.

3. Final Answer:

   Using beforeEach to reset state and avoid shared data -> Option D

4. Quick Check:

   Parallel tests need isolated state = beforeEach [OK]

Hint: Reset state before each test for reliable parallel runs [OK]

Common Mistakes:

• Sharing global variables causing conflicts
• Running tests without resetting state
• Disabling retries instead of fixing isolation