Overwriting existing commands in Cypress - Framework Patterns

Framework Mode - Overwriting existing commands

Folder Structure

  cypress/
  ├── e2e/                  # Test specs
  │   └── example.cy.js
  ├── support/              # Support files and custom commands
  │   ├── commands.js       # Custom and overwritten commands
  │   └── e2e.js            # Support file loaded before tests
  ├── fixtures/             # Test data files
  │   └── example.json
  cypress.config.js         # Cypress configuration file
  

Test Framework Layers

• Support Layer: Contains commands.js where existing Cypress commands are overwritten or new commands are added.
• Test Specs Layer: Located in cypress/e2e/, contains test files that use the commands.
• Fixtures Layer: Holds test data files used by tests.
• Configuration Layer: cypress.config.js manages environment settings.

Configuration Patterns

Use cypress.config.js to define environment variables, base URLs, and browser settings.

Example snippet to set environment variables:

  import { defineConfig } from 'cypress'

  export default defineConfig({
    e2e: {
      baseUrl: 'https://example.com',
      env: {
        username: 'testuser',
        password: 'securePass123'
      },
      setupNodeEvents(on, config) {
        // implement node event listeners here
      }
    }
  })
  

Access environment variables in tests or commands with Cypress.env('username').

Test Reporting and CI/CD Integration

• Use built-in Cypress reporters or integrate with mochawesome for detailed HTML reports.
• Configure CI pipelines (GitHub Actions, Jenkins, GitLab CI) to run Cypress tests headlessly.
• Save test reports and screenshots as artifacts for review.
• Example GitHub Actions step to run tests and upload reports:

  - name: Run Cypress Tests
    uses: cypress-io/github-action@v5
    with:
      browser: chrome
      headless: true
  

Best Practices for Overwriting Commands in Cypress

1. Keep Original Behavior: When overwriting, call originalFn to preserve existing functionality unless intentionally changing it.
2. Use Clear Naming: Overwrite commands only when necessary; avoid confusing names.
3. Centralize Overwrites: Place all overwritten commands in cypress/support/commands.js for easy maintenance.
4. Document Changes: Comment why and how commands are overwritten for team clarity.
5. Test Overwritten Commands: Write tests to verify the new behavior works as expected.

Self Check

Where in this folder structure would you add a new overwritten command for cy.click() to add a custom log message before clicking?

Key Result

In Cypress, overwrite existing commands by extending cypress/support/commands.js to customize behavior while preserving original functionality.

Practice

1. What is the main purpose of overwriting existing commands in Cypress?

easy

A. To change or extend the behavior of built-in Cypress commands

B. To delete commands from Cypress

C. To create new commands unrelated to existing ones

D. To speed up test execution by skipping commands

Solution

1. Step 1: Understand command overwriting

   Overwriting commands means changing how existing Cypress commands behave.

2. Step 2: Identify the purpose

   This lets you add features like logging or fix issues in commands.

3. Final Answer:

   To change or extend the behavior of built-in Cypress commands -> Option A

4. Quick Check:

   Overwriting = Change behavior [OK]

Hint: Overwriting means changing existing command behavior [OK]

Common Mistakes:

• Thinking overwriting deletes commands
• Confusing overwriting with creating new commands
• Assuming overwriting speeds up tests automatically

2. Which of the following is the correct syntax to overwrite the click command in Cypress?

easy

A. Cypress.Commands.add('click', (subject, options) => { return subject.click(options) })

B. Cypress.Commands.override('click', (originalFn, subject) => { originalFn(subject) })

C. Cypress.overwrite('click', (subject, options) => { return subject.click(options) })

D. Cypress.Commands.overwrite('click', (originalFn, subject, options) => { return originalFn(subject, options) })

Solution

1. Step 1: Recall Cypress overwrite syntax

   Use Cypress.Commands.overwrite with the command name and a function receiving originalFn.

2. Step 2: Check parameters and call

   The function must call originalFn(subject, options) to keep original behavior.

3. Final Answer:

   Cypress.Commands.overwrite('click', (originalFn, subject, options) => { return originalFn(subject, options) }) -> Option D

4. Quick Check:

   Overwrite syntax = Cypress.Commands.overwrite [OK]

Hint: Use Cypress.Commands.overwrite with originalFn first param [OK]

Common Mistakes:

• Using Cypress.Commands.add instead of overwrite
• Wrong method name like override
• Missing originalFn parameter

3. Given this overwrite code:

Cypress.Commands.overwrite('type', (originalFn, subject, text, options) => {
  cy.log(`Typing: ${text}`)
  return originalFn(subject, text, options)
})

What will happen when cy.get('input').type('hello') runs?

medium

A. It types 'hello' and logs 'Typing: hello' in the test runner

B. It types 'hello' but does not log anything

C. It throws an error because of wrong parameters

D. It logs 'Typing: hello' but does not type anything

Solution

1. Step 1: Analyze the overwrite function

   The overwrite logs the text being typed, then calls the original type command with all parameters.

2. Step 2: Understand the effect on cy.type

   When cy.get('input').type('hello') runs, it logs the message and types 'hello' into the input.

3. Final Answer:

   It types 'hello' and logs 'Typing: hello' in the test runner -> Option A

4. Quick Check:

   Overwrite logs then calls original = logs and types [OK]

Hint: Overwrite calls originalFn after logging to keep behavior [OK]

Common Mistakes:

• Assuming logging prevents typing
• Thinking parameters are incorrect
• Believing it throws an error

4. What is wrong with this overwrite code?

Cypress.Commands.overwrite('click', (subject, options) => {
  cy.log('Clicking element')
  return subject.click(options)
})

medium

A. It should use Cypress.Commands.add instead of overwrite

B. It misses the originalFn parameter required for overwriting

C. It uses cy.log which is not allowed inside overwrites

D. It calls subject.click instead of originalFn

Solution

1. Step 1: Check overwrite function parameters

   Overwrites must receive originalFn as the first parameter to call the original command.

2. Step 2: Identify missing parameter

   This code only has subject and options, missing originalFn.

3. Final Answer:

   It misses the originalFn parameter required for overwriting -> Option B

4. Quick Check:

   Overwrite needs originalFn first param [OK]

Hint: Overwrite must have originalFn as first parameter [OK]

Common Mistakes:

• Omitting originalFn parameter
• Confusing add with overwrite
• Thinking cy.log is disallowed

5. You want to overwrite the visit command to add a console log only when the URL contains 'admin'. Which overwrite code correctly implements this?

hard

A. Cypress.Commands.overwrite('visit', (url, options) => {
if (url.includes('admin')) {
console.log('Admin page visited')
}
return cy.visit(url, options)
})

B. Cypress.Commands.overwrite('visit', (originalFn, url, options) => {
if (url.includes('admin')) {
console.log('Admin page visited')
}
return originalFn(options, url)
})

C. Cypress.Commands.overwrite('visit', (originalFn, url, options) => {
if (url.includes('admin')) {
console.log('Admin page visited')
}
return originalFn(url, options)
})

D. Cypress.Commands.add('visit', (url, options) => {
if (url.includes('admin')) {
console.log('Admin page visited')
}
cy.visit(url, options)
})

Solution

1. Step 1: Use correct overwrite signature

   Overwrite must have originalFn as first parameter, then url and options.

2. Step 2: Call originalFn with correct argument order

   Call originalFn(url, options) to keep original behavior.

3. Step 3: Add conditional console log

   Check if url.includes('admin') and log message accordingly.

4. Final Answer:

   Cypress.Commands.overwrite('visit', (originalFn, url, options) => { if (url.includes('admin')) { console.log('Admin page visited') } return originalFn(url, options) }) -> Option C

5. Quick Check:

   Overwrite with originalFn and correct args [OK]

Hint: Always call originalFn with correct parameters in overwrite [OK]

Common Mistakes:

• Swapping url and options in call
• Using add instead of overwrite
• Omitting originalFn parameter