Visual regression testing concept in Cypress - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to take a screenshot for visual regression testing.

Cypress

cy.visit('https://example.com')
cy.[1]('homepage')

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

Areload

Btype

Cclick

Dscreenshot

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'click' instead of 'screenshot' will not capture the page image.

Using 'type' or 'reload' does not take screenshots.

The screenshot command captures the current page view for visual regression testing.

2fill in blank

medium

Complete the code to compare the current screenshot with the baseline image.

Cypress

cy.matchImageSnapshot([1])

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

A'homepage'

B'homepage.png'

C'baseline.png'

D'compare'

Attempts:

3 left

💡 Hint

Common Mistakes

Including file extensions causes errors.

Using unrelated strings will not match the correct snapshot.

The matchImageSnapshot function takes a name string to identify the snapshot, usually without file extension.

3fill in blank

hard

Fix the error in the code to properly set the viewport size for visual regression testing.

Cypress

cy.viewport([1], 800)

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

A1024

Bwidth

C'1024'

D'1024px'

Attempts:

3 left

💡 Hint

Common Mistakes

Using strings with units like '1024px' causes errors.

Using variable names instead of numbers is incorrect here.

The viewport width must be a number, not a string.

4fill in blank

hard

Fill both blanks to create a dictionary of viewport sizes and filter only those wider than 500 pixels.

Cypress

const viewports = { 'small': 320, 'medium': 768, 'large': 1024 };
const filtered = Object.entries(viewports).filter(([[1], [2]]) => [2] > 500);

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

Akey

Bvalue

Cwidth

Dsize

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect variable names that do not match the entries structure.

Comparing the key instead of the value.

When filtering entries, the first element is the key and the second is the value.

5fill in blank

hard

Fill all three blanks to create a test that visits a page, sets viewport, and takes a snapshot named 'homepage'.

Cypress

describe('Visual test', () => {
  it('checks homepage', () => {
    cy.visit([1])
    cy.viewport([2], 800)
    cy.screenshot([3])
  })
})

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

A'https://example.com'

B1024

C'homepage'

D'/home'

Attempts:

3 left

💡 Hint

Common Mistakes

Using partial URLs or paths in visit causes errors.

Passing viewport width as a string causes errors.

Not naming the screenshot properly.

The test visits the full URL, sets viewport width as a number, and names the screenshot 'homepage'.

Practice

1. What is the main purpose of visual regression testing in Cypress?

easy

A. To check if the webpage links are working

B. To test the speed of webpage loading

C. To verify the correctness of backend data processing

D. To check if the webpage appearance changes unexpectedly after updates

Solution

1. Step 1: Understand visual regression testing goal

   Visual regression testing compares screenshots to detect visual changes.

2. Step 2: Identify the main purpose in Cypress context

   Cypress uses visual regression to ensure UI looks the same after code changes.

3. Final Answer:

   To check if the webpage appearance changes unexpectedly after updates -> Option D

4. Quick Check:

   Visual regression = check appearance changes [OK]

Hint: Visual regression tests page look, not speed or links [OK]

Common Mistakes:

• Confusing visual regression with performance testing
• Thinking it tests backend logic
• Assuming it checks link functionality

2. Which Cypress command is used to take a snapshot for visual regression testing?

easy

A. cy.get()

B. cy.visit()

C. cy.matchImageSnapshot()

D. cy.click()

Solution

1. Step 1: Identify commands related to visual regression

   cy.matchImageSnapshot() is designed to compare screenshots for visual testing.

2. Step 2: Differentiate from other Cypress commands

   cy.visit() loads pages, cy.get() selects elements, cy.click() simulates clicks.

3. Final Answer:

   cy.matchImageSnapshot() -> Option C

4. Quick Check:

   Snapshot command = cy.matchImageSnapshot() [OK]

Hint: Snapshot command has 'matchImage' in its name [OK]

Common Mistakes:

• Choosing cy.visit() which loads pages
• Confusing cy.get() with snapshot command
• Selecting cy.click() which triggers clicks

3. What will happen if the following Cypress test runs and the page appearance has changed since the last snapshot?

cy.visit('https://example.com')
cy.matchImageSnapshot('homepage')

medium

A. The test fails because the new screenshot differs from the saved snapshot

B. The test reloads the page automatically

C. The test passes because it always ignores visual differences

D. The test skips the snapshot comparison

Solution

1. Step 1: Understand snapshot comparison behavior

   cy.matchImageSnapshot compares current screenshot to saved snapshot and fails if different.

2. Step 2: Apply this to changed page appearance

   If the page looks different, the test detects difference and fails.

3. Final Answer:

   The test fails because the new screenshot differs from the saved snapshot -> Option A

4. Quick Check:

   Visual difference causes test failure [OK]

Hint: Changed appearance means snapshot test fails [OK]

Common Mistakes:

• Thinking test always passes regardless of changes
• Assuming test reloads page automatically
• Believing snapshot comparison is skipped

4. Identify the error in this Cypress visual regression test code:

cy.matchImageSnapshot('homepage')
cy.visit('https://example.com')

medium

A. cy.visit() should be called before cy.matchImageSnapshot()

B. cy.matchImageSnapshot() cannot take a string argument

C. cy.visit() is not a valid Cypress command

D. The test is missing cy.get() before snapshot

Solution

1. Step 1: Check command order for visual testing

   Page must be loaded with cy.visit() before taking a snapshot.

2. Step 2: Verify argument and command validity

   cy.matchImageSnapshot() accepts a string name; cy.visit() is valid; cy.get() not required here.

3. Final Answer:

   cy.visit() should be called before cy.matchImageSnapshot() -> Option A

4. Quick Check:

   Visit page first, then snapshot [OK]

Hint: Always visit page before snapshot command [OK]

Common Mistakes:

• Calling snapshot before loading page
• Thinking cy.matchImageSnapshot() disallows string names
• Assuming cy.visit() is invalid
• Believing cy.get() is mandatory before snapshot

5. You want to add visual regression testing for a login page that changes its welcome message based on the user. How should you handle this dynamic content in Cypress visual regression tests?

hard

A. Use a custom snapshot name for each user to save separate images

B. Ignore the dynamic area by masking or hiding it before snapshot

C. Remove cy.visit() to avoid loading the page

D. Run cy.matchImageSnapshot() twice to average results

Solution

1. Step 1: Understand problem with dynamic content

   Dynamic text changes cause snapshot differences and false failures.

2. Step 2: Choose best practice to handle dynamic parts

   Masking or hiding dynamic areas before snapshot avoids false positives.

3. Step 3: Evaluate other options

   Custom names create many snapshots; removing cy.visit() breaks test; averaging snapshots is invalid.

4. Final Answer:

   Ignore the dynamic area by masking or hiding it before snapshot -> Option B

5. Quick Check:

   Mask dynamic content to stabilize snapshots [OK]

Hint: Mask or hide changing parts before snapshot [OK]

Common Mistakes:

• Saving separate snapshots for each user causes clutter
• Skipping page load breaks test
• Trying to average snapshots is not supported