Why Cypress.Commands.add()? - Purpose & Use Cases

The Big Idea

What if you could write a test step once and use it everywhere without copying?

The Scenario

Imagine testing a website where you have to log in many times manually by typing the username and password each time in your test scripts.

You copy and paste the same steps over and over in every test.

The Problem

This manual way is slow and boring.

It's easy to make mistakes copying the same steps repeatedly.

If the login process changes, you must update every test, which wastes time and causes errors.

The Solution

Cypress.Commands.add() lets you create your own custom commands.

You write the login steps once, then reuse them everywhere by calling your new command.

This saves time, reduces mistakes, and makes tests easier to update.

Before vs After

✗ Before

cy.get('#username').type('user')
cy.get('#password').type('pass')
cy.get('#login').click()

✓ After

Cypress.Commands.add('login', () => {
  cy.get('#username').type('user')
  cy.get('#password').type('pass')
  cy.get('#login').click()
})

cy.login()

What It Enables

You can build a library of reusable commands that make your tests cleaner, faster, and easier to maintain.

Real Life Example

In a big project, you create a custom command for logging in once.

Every test just calls cy.login() instead of repeating the login steps.

When the login changes, you update only one place.

Key Takeaways

Manual repetition of test steps is slow and error-prone.

Cypress.Commands.add() creates reusable custom commands.

Custom commands make tests simpler and easier to maintain.

Practice

1. What is the main purpose of Cypress.Commands.add() in Cypress testing?

easy

A. To configure browser settings

B. To add new test cases automatically

C. To create reusable custom commands for cleaner test code

D. To generate test reports

Solution

1. Step 1: Understand the function of Cypress.Commands.add()

   This method allows you to define your own commands that you can reuse in tests.

2. Step 2: Identify the benefit of reusable commands

   Reusable commands help keep test code clean and avoid repetition.

3. Final Answer:

   To create reusable custom commands for cleaner test code -> Option C

4. Quick Check:

   Reusable commands = Cleaner code [OK]

Hint: Remember: add() creates custom commands you can reuse [OK]

Common Mistakes:

• Thinking it adds test cases automatically
• Confusing it with test report generation
• Assuming it changes browser settings

2. Which of the following is the correct syntax to add a custom command named login in Cypress?

easy

A. Cypress.Commands.create('login', () => { /* code */ })

B. Cypress.addCommand('login', () => { /* code */ })

C. Commands.add('login', () => { /* code */ })

D. Cypress.Commands.add('login', () => { /* code */ })

Solution

1. Step 1: Recall the correct method name

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

2. Step 2: Check the syntax format

   The first argument is the command name as a string, the second is a function.

3. Final Answer:

   Cypress.Commands.add('login', () => { /* code */ }) -> Option D

4. Quick Check:

   Correct method and syntax = Cypress.Commands.add('login', () => { /* code */ }) [OK]

Hint: Use Cypress.Commands.add('name', function) always [OK]

Common Mistakes:

• Using Cypress.addCommand instead of Commands.add
• Omitting Cypress.Commands prefix
• Using create instead of add

3. Given the code below, what will be the output when cy.login() is called in a test?

 Cypress.Commands.add('login', (username, password) => {
  cy.get('#user').type(username)
  cy.get('#pass').type(password)
  cy.get('#submit').click()
})

// In test
cy.login('user1', 'pass1')

medium

A. Types 'user1' in #user, 'pass1' in #pass, then clicks #submit

B. Throws an error because login needs no parameters

C. Clicks #submit without typing anything

D. Types 'user1' in #pass and 'pass1' in #user

Solution

1. Step 1: Analyze the custom command parameters

   The command takes username and password and types them into respective fields.

2. Step 2: Follow the command actions

   It types username into '#user', password into '#pass', then clicks '#submit'.

3. Final Answer:

   Types 'user1' in #user, 'pass1' in #pass, then clicks #submit -> Option A

4. Quick Check:

   Parameters map to correct fields = Types 'user1' in #user, 'pass1' in #pass, then clicks #submit [OK]

Hint: Match parameters to fields carefully [OK]

Common Mistakes:

• Assuming no parameters are needed
• Mixing up username and password fields
• Ignoring the click action

4. Identify the error in the following custom command definition:

 Cypress.Commands.add('clickButton', () => {
  cy.get('#button')
  cy.click()
})

medium

A. Missing chaining of click() to cy.get()

B. Wrong command name, should be clickbutton

C. Should use cy.find() instead of cy.get()

D. No error, code is correct

Solution

1. Step 1: Review the command chaining

   cy.get('#button') returns an element, but cy.click() is called separately, not chained.

2. Step 2: Understand correct chaining

   Click should be chained to the element: cy.get('#button').click().

3. Final Answer:

   Missing chaining of click() to cy.get() -> Option A

4. Quick Check:

   Method chaining required = Missing chaining of click() to cy.get() [OK]

Hint: Always chain commands like cy.get(...).click() [OK]

Common Mistakes:

• Calling cy.click() separately
• Changing command name unnecessarily
• Using cy.find() instead of cy.get() without reason

5. You want to create a custom command fillForm that fills multiple fields and submits a form. Which approach correctly uses Cypress.Commands.add() to accept an object with field values and perform the actions?

hard

A. Cypress.Commands.add('fillForm', () => {
cy.get('#name').type(name)
cy.get('#email').type(email)
cy.get('#submit').click()
})

B. Cypress.Commands.add('fillForm', (data) => {
cy.get('#name').type(data.name)
cy.get('#email').type(data.email)
cy.get('#submit').click()
})

C. Cypress.Commands.add('fillForm', (name, email) => {
cy.get('#name').type(name)
cy.get('#email').type(email)
cy.get('#submit').click()
})

D. Cypress.Commands.add('fillForm', (data) => {
cy.get('#name').type(data[0])
cy.get('#email').type(data[1])
cy.get('#submit').click()
})

Solution

1. Step 1: Understand parameter passing

   Using a single object parameter data with named properties is clear and flexible.

2. Step 2: Check usage of object properties

   Accessing data.name and data.email matches the object keys.

3. Final Answer:

   Cypress.Commands.add('fillForm', (data) => { cy.get('#name').type(data.name) cy.get('#email').type(data.email) cy.get('#submit').click() }) -> Option B

4. Quick Check:

   Object parameter with named fields = Cypress.Commands.add('fillForm', (data) => { cy.get('#name').type(data.name) cy.get('#email').type(data.email) cy.get('#submit').click() }) [OK]

Hint: Pass one object with named fields for clarity [OK]

Common Mistakes:

• Using undefined variables without parameters
• Passing multiple parameters instead of one object
• Accessing object fields by index instead of name