Responsive breakpoint testing in Cypress

Introduction

Responsive breakpoint testing checks if a website looks and works well on different screen sizes. It helps make sure users have a good experience on phones, tablets, and desktops.

When you want to test if a menu changes correctly on small screens.

When you need to verify that images resize properly on tablets.

When checking if text and buttons stay readable on mobile devices.

When making sure layout elements stack or align as expected at different widths.

When testing a new design that should adapt to various screen sizes.

Syntax

Cypress

cy.viewport(width, height)
// or
cy.viewport(presetName)

// Then write tests to check page elements after setting viewport

cy.viewport() sets the browser size for the test.

You can use common device names like 'iphone-6', 'ipad-2', or specify width and height in pixels.

Examples

This sets a small mobile screen size for testing.

Cypress

cy.viewport(320, 480)
// sets viewport to 320px wide and 480px tall

Use a preset device size for convenience.

Cypress

cy.viewport('ipad-2')
// sets viewport to iPad 2 dimensions

Test how the site looks on a laptop screen.

Cypress

cy.viewport('macbook-15')
// sets viewport to 1440x900 for a laptop screen

Sample Program

This test checks if the mobile menu button appears on a small screen and the full desktop menu appears on a larger screen.

Cypress

describe('Responsive Breakpoint Testing', () => {
  it('shows mobile menu on small screens', () => {
    cy.viewport('iphone-6')
    cy.visit('https://example.cypress.io')
    cy.get('.mobile-menu-button').should('be.visible')
  })

  it('shows full menu on desktop screens', () => {
    cy.viewport(1280, 720)
    cy.visit('https://example.cypress.io')
    cy.get('.desktop-menu').should('be.visible')
  })
})

Important Notes

Always set the viewport before visiting the page to ensure the page loads with the correct size.

Use assertions that check visibility or layout changes specific to each breakpoint.

Test multiple breakpoints to cover common device sizes.

Summary

Responsive breakpoint testing uses cy.viewport() to simulate different screen sizes.

It helps verify that UI elements adapt correctly on phones, tablets, and desktops.

Write separate tests for each important screen size to catch layout issues early.

Practice

1. What is the main purpose of using cy.viewport() in Cypress tests?

easy

A. To capture screenshots of the current page

B. To speed up test execution by skipping UI rendering

C. To mock API responses during tests

D. To simulate different screen sizes for responsive testing

Solution

1. Step 1: Understand cy.viewport() role

   cy.viewport() changes the browser size to simulate devices.

2. Step 2: Identify its use in responsive testing

   This helps check if UI adapts correctly on phones, tablets, and desktops.

3. Final Answer:

   To simulate different screen sizes for responsive testing -> Option D

4. Quick Check:

   cy.viewport() = simulate screen sizes [OK]

Hint: Remember: viewport changes screen size for layout checks [OK]

Common Mistakes:

• Confusing viewport with API mocking
• Thinking it speeds up tests by skipping UI
• Assuming it captures screenshots

2. Which of the following is the correct syntax for the iPhone 6 viewport preset in Cypress?

easy

A. cy.viewport('iphone-6')

B. cy.viewport(375, 667)

C. cy.viewport('iPhone6')

D. cy.setViewport('iphone-6')

Solution

1. Step 1: Recall Cypress viewport presets

   Cypress supports device names like 'iphone-6' in cy.viewport().

2. Step 2: Check syntax correctness

   cy.viewport('iphone-6') uses correct method and exact device name string.

3. Final Answer:

   cy.viewport('iphone-6') -> Option A

4. Quick Check:

   Correct device name string in cy.viewport() [OK]

Hint: Use exact device names in quotes with cy.viewport() [OK]

Common Mistakes:

• Using wrong method name like cy.setViewport()
• Incorrect device name casing or spelling
• Passing numbers without quotes for presets

3. What will be the result of this Cypress test snippet?

cy.viewport('ipad-2')
cy.get('.menu').should('be.visible')

medium

A. Test ignores viewport and checks .menu visibility on default size

B. Test passes if .menu is visible on iPad 2 screen size

C. Test throws syntax error due to missing semicolon

D. Test fails because 'ipad-2' is not a valid viewport preset

Solution

1. Step 1: Understand viewport preset 'ipad-2'

   'ipad-2' is a valid Cypress preset simulating iPad 2 screen size.

2. Step 2: Analyze assertion behavior

   The test checks if element with class .menu is visible at that size.

3. Final Answer:

   Test passes if .menu is visible on iPad 2 screen size -> Option B

4. Quick Check:

   Valid preset + visibility check = pass if visible [OK]

Hint: Valid preset means viewport changes; assertion checks visibility [OK]

Common Mistakes:

• Thinking 'ipad-2' is invalid preset
• Assuming missing semicolons cause errors in Cypress
• Believing viewport is ignored without explicit reload

4. Identify the error in this Cypress test for responsive breakpoint:

cy.viewport(1024, 768)
cy.get('#nav').should('be.visible')
cy.viewport('mobile')
cy.get('#nav').should('not.be.visible')

medium

A. Incorrect selector '#nav' should be '.nav'

B. Missing wait between viewport changes causes flaky test

C. Invalid viewport preset 'mobile' causes test failure

D. Assertions are reversed; nav should be visible on mobile

Solution

1. Step 1: Check viewport presets used

   1024x768 is valid, but 'mobile' is not a recognized preset in Cypress.

2. Step 2: Understand impact of invalid preset

   Using 'mobile' causes Cypress to throw an error and fail the test.

3. Final Answer:

   Invalid viewport preset 'mobile' causes test failure -> Option C

4. Quick Check:

   Use only valid viewport presets [OK]

Hint: Use only Cypress documented viewport presets [OK]

Common Mistakes:

• Assuming 'mobile' is a valid preset
• Thinking missing waits cause failure here
• Confusing selector correctness with viewport issues

5. You want to test a web page's header visibility on desktop (1440x900) and mobile (375x667). Which is the best Cypress test approach?

hard

A. Write two separate tests using cy.viewport(1440, 900) and cy.viewport(375, 667) with visibility assertions

B. Write one test with cy.viewport(1440, 900) only, assuming mobile works the same

C. Use cy.viewport('iphone-x') only, ignoring desktop size

D. Test only on default viewport size without changing viewport

Solution

1. Step 1: Understand responsive testing goal

   We want to verify header visibility on both desktop and mobile screen sizes.

2. Step 2: Choose best Cypress approach

   Writing separate tests with explicit viewport sizes ensures coverage of both layouts.

3. Final Answer:

   Write two separate tests using cy.viewport(1440, 900) and cy.viewport(375, 667) with visibility assertions -> Option A

4. Quick Check:

   Separate viewport tests cover all breakpoints [OK]

Hint: Test each breakpoint separately for reliable responsive checks [OK]

Common Mistakes:

• Assuming one viewport size covers all devices
• Ignoring desktop or mobile viewport testing
• Relying on default viewport without changes