Dynamic response stubbing in Cypress - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to stub a GET request with a dynamic response.

Cypress

cy.intercept('GET', '/api/users', [1]).as('getUsers')

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

A{ fixture: 'users.json' }

B{ statusCode: 200, body: [{ id: 1, name: 'Alice' }] }

C{ delay: 1000 }

D{ method: 'POST' }

Attempts:

3 left

💡 Hint

Common Mistakes

Using fixture instead of inline response.

Setting wrong HTTP method in stub.

Omitting statusCode in response.

The stub must provide a dynamic response body with status 200 and user data.

2fill in blank

medium

Complete the code to stub a POST request and return a custom response.

Cypress

cy.intercept('POST', '/api/login', (req) => { req.reply({ [1] }) }).as('postLogin')

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

AstatusCode: 200, body: { token: 'abc123' }

BstatusCode: 404, body: { error: 'Not found' }

CstatusCode: 500, body: { error: 'Server error' }

DstatusCode: 401, body: { error: 'Unauthorized' }

Attempts:

3 left

💡 Hint

Common Mistakes

Using error status codes for a successful login stub.

Omitting the token in the response body.

The stub should simulate a successful login with status 200 and a token in the body.

3fill in blank

hard

Fix the error in the stub to correctly delay the response by 2 seconds.

Cypress

cy.intercept('GET', '/api/data', { [1] }).as('getData')

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

Atimeout: 2000, body: { data: [] }

Bwait: 2000, body: { data: [] }

Cpause: 2000, body: { data: [] }

Ddelay: 2000, body: { data: [] }

Attempts:

3 left

💡 Hint

Common Mistakes

Using incorrect property names like wait, timeout, or pause.

Omitting the delay property.

The correct property to delay response is delay with milliseconds.

4fill in blank

hard

Fill both blanks to stub a GET request that returns a 404 status with a custom error message.

Cypress

cy.intercept('GET', '/api/item/[1]', { statusCode: [2], body: { error: 'Item not found' } }).as('getItem')

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

A:id

B404

C500

D:itemId

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong dynamic segment syntax like ':itemId'.

Using wrong status code like 500 instead of 404.

The URL uses a dynamic parameter :id and the status code for not found is 404.

5fill in blank

hard

Fill all three blanks to stub a PUT request that updates a user and returns the updated user data with status 200.

Cypress

cy.intercept('PUT', '/api/users/[1]', (req) => { req.reply({ statusCode: [2], body: [3] }) }).as('updateUser')

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

A:userId

B200

C{ id: req.body.id, name: req.body.name }

D201

Attempts:

3 left

💡 Hint

Common Mistakes

Using wrong status code like 201 for update.

Not returning updated user data in the body.

Using incorrect dynamic segment syntax.

The URL uses :userId as dynamic param, status 200 means success, and the body returns updated user data from the request.

Practice

1. What is the main purpose of dynamic response stubbing in Cypress tests?

easy

A. To change server responses during tests to simulate different scenarios

B. To speed up the browser rendering process

C. To automatically generate test data from the server

D. To record user interactions for playback

Solution

1. Step 1: Understand dynamic response stubbing

   Dynamic response stubbing allows tests to modify server replies on the fly to simulate various conditions.

2. Step 2: Identify the main goal

   This helps test how the app behaves with different data or errors without relying on real server responses.

3. Final Answer:

   To change server responses during tests to simulate different scenarios -> Option A

4. Quick Check:

   Dynamic stubbing = simulate different server replies [OK]

Hint: Dynamic stubbing means changing server replies during tests [OK]

Common Mistakes:

• Confusing stubbing with speeding up rendering
• Thinking it generates test data automatically
• Mixing it up with recording user actions

2. Which of the following is the correct way to stub a dynamic response using cy.intercept in Cypress?

easy

A. cy.intercept('GET', '/api/data', { status: 200, body: { value: 42 } })

B. cy.intercept('GET', '/api/data', (res) => { res.send({ value: 42 }) })

C. cy.intercept('GET', '/api/data', () => { return { value: 42 } })

D. cy.intercept('GET', '/api/data', (req) => { req.reply({ body: { value: 42 } }) })

Solution

1. Step 1: Recall cy.intercept syntax for dynamic stubbing

   To modify the response dynamically, use a callback with the request object and call req.reply() with the new body.

2. Step 2: Check each option

   cy.intercept('GET', '/api/data', (req) => { req.reply({ body: { value: 42 } }) }) correctly uses (req) => { req.reply({ body: ... }) }. cy.intercept('GET', '/api/data', { status: 200, body: { value: 42 } }) is static stubbing, C returns a value incorrectly, D uses res.send which is not Cypress syntax.

3. Final Answer:

   cy.intercept('GET', '/api/data', (req) => { req.reply({ body: { value: 42 } }) }) -> Option D

4. Quick Check:

   Dynamic stub uses req.reply() callback [OK]

Hint: Use req.reply() inside intercept callback for dynamic response [OK]

Common Mistakes:

• Using static object instead of callback for dynamic stubbing
• Returning response instead of calling req.reply()
• Using incorrect callback parameter names

3. Given the following Cypress code, what will be the response body when the app requests '/api/user'?

cy.intercept('GET', '/api/user', (req) => {
  const id = req.query.id
  if (id === '1') {
    req.reply({ body: { name: 'Alice' } })
  } else {
    req.reply({ body: { name: 'Guest' } })
  }
})

The app calls fetch('/api/user?id=1'). What is the response?

medium

A. Empty response body

B. { name: 'Guest' }

C. { name: 'Alice' }

D. An error occurs because req.query is undefined

Solution

1. Step 1: Analyze the intercept callback logic

   The callback checks req.query.id. If it equals '1', it replies with { name: 'Alice' }, else { name: 'Guest' }.

2. Step 2: Check the request URL query

   The app calls '/api/user?id=1', so req.query.id is '1'. Therefore, the response is { name: 'Alice' }.

3. Final Answer:

   { name: 'Alice' } -> Option C

4. Quick Check:

   Query id '1' returns Alice [OK]

Hint: Match query params in req.query to decide response [OK]

Common Mistakes:

• Assuming req.query is undefined in Cypress intercept
• Ignoring query parameters in the stub
• Confusing string and number types in comparison

4. Identify the error in this Cypress dynamic stub code:

cy.intercept('POST', '/api/login', (req) => {
  req.reply({ statusCode: 200, body: { token: 'abc123' } })
})

The test fails with an error about req.reply not being a function. What is wrong?

medium

A. The callback receives req but req.reply is not a function; should use req.continue

B. The callback parameter should be interception and interception.reply used

C. The callback parameter is correct, but req.reply is only available on res

D. The callback parameter should be named res instead of req

Solution

1. Step 1: Understand intercept callback parameter

   The callback receives an interception object, often named interception, which has the reply method.

2. Step 2: Identify the naming and usage error

   Using req as parameter is allowed but req.reply is not a function because the object is not the request but the interception. The correct approach is to name it interception and call interception.reply().

3. Final Answer:

   The callback parameter should be interception and interception.reply used -> Option B

4. Quick Check:

   Use interception.reply() in intercept callback [OK]

Hint: Use interception.reply(), not req.reply(), in intercept callback [OK]

Common Mistakes:

• Confusing request object with interception object
• Using req.reply() which does not exist
• Misnaming callback parameter causing method errors

5. You want to stub a GET request to '/api/items' so that the response body depends on a query parameter 'type'. If 'type' is 'fruit', respond with { items: ['apple', 'banana'] }. If 'type' is 'vegetable', respond with { items: ['carrot', 'lettuce'] }. Otherwise, respond with { items: [] }. Which code correctly implements this dynamic response stubbing?

hard

A. cy.intercept('GET', '/api/items', (interception) => {
const type = interception.query.type
if (type === 'fruit') {
interception.reply({ body: { items: ['apple', 'banana'] } })
} else if (type === 'vegetable') {
interception.reply({ body: { items: ['carrot', 'lettuce'] } })
} else {
interception.reply({ body: { items: [] } })
}
})

B. cy.intercept('GET', '/api/items', (req) => {
if (req.query.type === 'fruit') {
req.reply({ items: ['apple', 'banana'] })
} else if (req.query.type === 'vegetable') {
req.reply({ items: ['carrot', 'lettuce'] })
} else {
req.reply({ items: [] })
}
})

C. cy.intercept('GET', '/api/items', (req) => {
const type = req.query.type
if (type === 'fruit') {
req.reply({ body: { items: ['apple', 'banana'] } })
} else if (type === 'vegetable') {
req.reply({ body: { items: ['carrot', 'lettuce'] } })
} else {
req.reply({ body: { items: [] } })
}
})

D. cy.intercept('GET', '/api/items', (interception) => {
const type = interception.query.type
if (type === 'fruit') {
interception.send({ body: { items: ['apple', 'banana'] } })
} else if (type === 'vegetable') {
interception.send({ body: { items: ['carrot', 'lettuce'] } })
} else {
interception.send({ body: { items: [] } })
}
})

Solution

1. Step 1: Identify correct parameter and method usage

   The callback parameter should be named interception (or similar) and use interception.reply() to send the response with a body property.

2. Step 2: Check each option for correctness

   cy.intercept('GET', '/api/items', (interception) => { const type = interception.query.type if (type === 'fruit') { interception.reply({ body: { items: ['apple', 'banana'] } }) } else if (type === 'vegetable') { interception.reply({ body: { items: ['carrot', 'lettuce'] } }) } else { interception.reply({ body: { items: [] } }) } }) correctly uses interception.query.type and calls interception.reply({ body: ... }). cy.intercept('GET', '/api/items', (req) => { if (req.query.type === 'fruit') { req.reply({ items: ['apple', 'banana'] }) } else if (req.query.type === 'vegetable') { req.reply({ items: ['carrot', 'lettuce'] }) } else { req.reply({ items: [] }) } }) misses body wrapper. cy.intercept('GET', '/api/items', (req) => { const type = req.query.type if (type === 'fruit') { req.reply({ body: { items: ['apple', 'banana'] } }) } else if (type === 'vegetable') { req.reply({ body: { items: ['carrot', 'lettuce'] } }) } else { req.reply({ body: { items: [] } }) } }) uses req but req.reply is not a function. cy.intercept('GET', '/api/items', (interception) => { const type = interception.query.type if (type === 'fruit') { interception.send({ body: { items: ['apple', 'banana'] } }) } else if (type === 'vegetable') { interception.send({ body: { items: ['carrot', 'lettuce'] } }) } else { interception.send({ body: { items: [] } }) } }) uses interception.send which is not a Cypress method.

3. Final Answer:

   Option A code correctly implements dynamic response stubbing with query check and reply -> Option A

4. Quick Check:

   Use interception.reply({ body }) and check interception.query [OK]

Hint: Use interception.reply({ body }) and check interception.query.type [OK]

Common Mistakes:

• Using req.reply() which is undefined
• Omitting the body wrapper in reply
• Using interception.send() which does not exist