Overwriting existing commands in Cypress - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does it mean to overwrite an existing command in Cypress?

It means replacing or extending a built-in Cypress command with your own version to customize its behavior.

beginner

How do you overwrite a Cypress command?

Use Cypress.Commands.overwrite('commandName', (originalFn, ...args) => { ... }) to replace the command.

intermediate

Why should you call the original command function inside your overwritten command?

To keep the original behavior and add extra steps, ensuring your changes don’t break existing functionality.

intermediate

Example: Overwrite click command to log a message before clicking. What is the correct way?

Use Cypress.Commands.overwrite('click', (originalFn, subject, options) => { console.log('Clicking element'); return originalFn(subject, options); }).

intermediate

What happens if you overwrite a command but do NOT call the original function?

The original command’s behavior is skipped, which may cause tests to fail or behave unexpectedly.

Which method is used to overwrite an existing Cypress command?

A Cypress.Commands.replace()

B Cypress.Commands.overwrite()

C Cypress.Commands.add()

D Cypress.Commands.modify()

The correct method to overwrite commands is Cypress.Commands.overwrite().

When overwriting a command, what is the first argument passed to your function?

A The original command function

B The command name

C The test context

D The command options

The first argument is the original command function, allowing you to call it inside your overwrite.

What is a good reason to overwrite a Cypress command?

A To slow down tests intentionally

B To delete the command permanently

C To add logging or extra checks before or after the original command

D To change Cypress configuration

Overwriting is useful to add extra behavior like logging or validation around the original command.

If you overwrite a command but forget to call the original function, what happens?

A The original command runs anyway

B The test passes without running the command

C Cypress throws an error automatically

D The command does nothing and may break tests

Not calling the original function means the command’s main action is skipped, likely breaking tests.

Where should you place your overwritten commands in a Cypress project?

A In the <code>cypress/support/commands.js</code> file

B In the test spec files

C In the <code>cypress/plugins</code> folder

D In the <code>cypress/fixtures</code> folder

Overwritten commands belong in cypress/support/commands.js to load before tests run.

Explain how to overwrite a Cypress command and why you might want to do it.

Think about customizing built-in commands without losing their original behavior.

Describe the risks of overwriting a command without calling the original function.

Consider what happens if the main action of a command is missing.

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