cy.first(), cy.last(), cy.eq() in Cypress - Framework Patterns

Framework Mode - cy.first(), cy.last(), cy.eq()

Folder Structure

  cypress/
  ├── e2e/                  # Test files
  │   ├── example.spec.js   # Example test using cy.first(), cy.last(), cy.eq()
  ├── fixtures/             # Test data files (JSON)
  ├── support/              # Custom commands and reusable utilities
  │   ├── commands.js       # Custom Cypress commands
  │   └── e2e.js            # Global setup for tests
  ├── pages/                # Page Object files
  │   └── examplePage.js    # Page object with element selectors
  cypress.config.js          # Cypress configuration file
  

Test Framework Layers

• Test Layer (cypress/e2e/): Contains test scripts that use .first(), .last(), and .eq() to select elements from lists or groups.
• Page Object Layer (cypress/pages/): Encapsulates selectors and actions for page elements, exposing collections for tests to apply .first(), .last(), .eq().
• Support Layer (cypress/support/): Holds reusable commands and setup code to keep tests clean and DRY (Don't Repeat Yourself).
• Configuration Layer (cypress.config.js): Manages environment settings, base URLs, and browser options.

Configuration Patterns

Use cypress.config.js to define:

• Base URL: Set the website URL to avoid repeating it in tests.
• Environment Variables: Store credentials or environment-specific data using env property.
• Browser Selection: Configure which browsers to run tests on via CLI or config.

Example snippet from cypress.config.js:

  import { defineConfig } from 'cypress'

  export default defineConfig({
    e2e: {
      baseUrl: 'https://example.com',
      env: {
        username: 'user1',
        password: 'pass123'
      },
      setupNodeEvents(on, config) {
        // implement node event listeners here
      }
    }
  })
  

Test Reporting and CI/CD Integration

• Use built-in Cypress Dashboard or plugins like mochawesome for detailed HTML reports.
• Integrate Cypress tests into CI/CD pipelines (GitHub Actions, Jenkins, GitLab CI) to run tests automatically on code changes.
• Configure test retries and screenshots/videos on failure for easier debugging.

Best Practices

• Use Page Objects: Keep selectors in page files and use .first(), .last(), .eq() in tests for clarity.
• Explicit Assertions: Always assert expected element state after selecting with .first() or .eq().
• Readable Tests: Use descriptive test names and comments when selecting elements by position.
• Handle Dynamic Lists: Use .first(), .last(), and .eq() carefully when list length can change.
• Reuse Selectors: Avoid hardcoding indexes; prefer semantic selectors or data attributes.

Self Check

Where in this folder structure would you add a new page object file for a list component that you want to test using .first(), .last(), and .eq()?

Key Result

Organize Cypress tests with clear folder layers, use page objects for selectors, and apply .first(), .last(), .eq() in tests for precise element selection.

Practice

1. What does cy.first() do in Cypress testing?

easy

A. Selects all elements matching a selector

B. Selects the last element from a group of matched elements

C. Selects the first element from a group of matched elements

D. Selects an element by its CSS class

Solution

1. Step 1: Understand the purpose of cy.first()

   cy.first() is used to pick the very first element from a list of elements found by a selector.

2. Step 2: Compare with other options

   Options A, B, and C describe different behaviors: last element, selecting by class, or selecting all elements, which are not what cy.first() does.

3. Final Answer:

   Selects the first element from a group of matched elements -> Option C

4. Quick Check:

   cy.first() = first element [OK]

Hint: Remember: first() picks the very first element [OK]

Common Mistakes:

• Confusing first() with last()
• Thinking first() selects by class or id
• Assuming first() selects all elements

2. Which of the following is the correct syntax to select the third element in a list using Cypress?

easy

A. cy.get('li').eq(2)

B. cy.get('li').eq(3)

C. cy.get('li').first(3)

D. cy.get('li').last(3)

Solution

1. Step 1: Recall zero-based indexing in eq()

   The eq() command uses zero-based index, so the third element is at index 2.

2. Step 2: Check syntax correctness

   cy.get('li').eq(2) uses eq(2) correctly. Options A, C, and D either use wrong index or invalid syntax.

3. Final Answer:

   cy.get('li').eq(2) -> Option A

4. Quick Check:

   Third element index = 2 [OK]

Hint: Remember eq() uses zero-based index, so third is eq(2) [OK]

Common Mistakes:

• Using eq(3) for the third element
• Trying to pass a number to first() or last()
• Confusing eq() with first() or last()

3. Given the following HTML:

<ul>
  <li>Apple</li>
  <li>Banana</li>
  <li>Cherry</li>
  <li>Date</li>
</ul>

What text will cy.get('li').last().invoke('text') return?

medium

A. "Cherry"

B. "Apple"

C. "Banana"

D. "Date"

Solution

1. Step 1: Identify what cy.last() selects

   cy.last() picks the last element in the matched list, which is the <li> containing "Date".

2. Step 2: Understand invoke('text')

   This command extracts the text content of the selected element, so it returns "Date".

3. Final Answer:

   "Date" -> Option D

4. Quick Check:

   last() element text = "Date" [OK]

Hint: last() picks last element's text content [OK]

Common Mistakes:

• Selecting first element text instead of last
• Confusing zero-based index with last()
• Expecting eq(3) to return "Date" without zero-based indexing

4. Consider this Cypress code snippet:

cy.get('button').eq(5).click()

It throws an error: "Cannot read property 'click' of undefined". What is the most likely cause?

medium

A. There are fewer than 6 buttons on the page, so eq(5) returns undefined

B. The syntax of eq() is incorrect; it should be eq[5]

C. click() cannot be chained after eq()

D. The selector 'button' is invalid

Solution

1. Step 1: Understand eq() index and element count

   eq(5) tries to select the 6th element (index 5). If fewer than 6 buttons exist, it returns undefined.

2. Step 2: Analyze error message

   The error "Cannot read property 'click' of undefined" means the element does not exist, so click() fails.

3. Final Answer:

   There are fewer than 6 buttons on the page, so eq(5) returns undefined -> Option A

4. Quick Check:

   Index out of range = undefined element [OK]

Hint: Check element count before using eq(index) [OK]

Common Mistakes:

• Using wrong eq() syntax
• Assuming click() can't chain after eq()
• Ignoring zero-based index causing out-of-range

5. You want to click the second-to-last item in a list of elements matched by cy.get('.item'). Which Cypress command chain correctly achieves this?

hard

A. cy.get('.item').eq(cy.get('.item').its('length').then(len => len - 2)).click()

B. cy.get('.item').eq(-2).click()

C. cy.get('.item').eq(-1).click({ force: true })

D. cy.get('.item').eq(cy.get('.item').length - 2).click()

Solution

1. Step 1: Recall eq() indexing in Cypress

   Cypress eq(n) supports negative indices: eq(-1) is last, eq(-2) is second-to-last.

2. Step 2: Compare options

   Options A and B have invalid syntax passing chainables to eq(). cy.get('.item').eq(-1).click({ force: true }) uses eq(-1) for last item. cy.get('.item').eq(-2).click() correctly uses eq(-2).

3. Final Answer:

   cy.get('.item').eq(-2).click() -> Option B

4. Quick Check:

   eq(-2) = second-to-last [OK]

Hint: eq() supports negative indices: -2 for second-to-last [OK]

Common Mistakes:

• Using negative index in eq() incorrectly (e.g., -1 instead of -2)
• Trying to subtract length directly without .then()
• Passing Cypress chainable as eq() argument