Asserting response bodies in Cypress - Test Execution Trace

Test Overview

This test sends a GET request to a sample API endpoint and verifies that the response body contains the expected data.

Test Code - Cypress

Cypress

describe('API Response Body Assertion', () => {
  it('should verify the response body contains expected user data', () => {
    cy.request('https://jsonplaceholder.typicode.com/users/1')
      .then((response) => {
        expect(response.status).to.equal(200);
        expect(response.body).to.have.property('id', 1);
        expect(response.body).to.have.property('username', 'Bret');
      });
  });
});

Execution Trace - 6 Steps

Step	Action	System State	Assertion	Result
1	Test starts	Cypress test runner initialized	—	PASS
2	Sends GET request to https://jsonplaceholder.typicode.com/users/1	Request sent, waiting for response	—	PASS
3	Receives response with status 200 and JSON body	Response received with user data	Check response.status equals 200	PASS
4	Asserts response body has property 'id' with value 1	Response body contains user object	response.body.id === 1	PASS
5	Asserts response body has property 'username' with value 'Bret'	Response body contains user object	response.body.username === 'Bret'	PASS
6	Test ends successfully	All assertions passed	—	PASS

Failure Scenario

Failing Condition: Response body does not contain the expected 'username' property with value 'Bret'

Execution Trace Quiz - 3 Questions

What does the test verify about the response status?

A It checks that the status code is 500

B It checks that the status code is 404

C It checks that the status code is 200

D It does not check the status code

Key Result

Always assert both the HTTP status code and key properties in the response body to ensure the API returns the expected data.

Practice

1. What is the main purpose of asserting response bodies in Cypress tests?

easy

A. To check if the UI elements are visible on the page

B. To verify the server sends the correct data in the response body

C. To measure the page load time

D. To test the browser compatibility

Solution

1. Step 1: Understand response body assertion

   Asserting response bodies means checking the data returned by the server is correct and as expected.

2. Step 2: Identify the purpose in Cypress tests

   Cypress uses assertions on response bodies to confirm the server sends the right data, not UI or performance checks.

3. Final Answer:

   To verify the server sends the correct data in the response body -> Option B

4. Quick Check:

   Response body assertion = verify server data [OK]

Hint: Response body assertions check server data, not UI or speed [OK]

Common Mistakes:

• Confusing response body with UI element checks
• Thinking it measures performance
• Assuming it tests browser features

2. Which of the following is the correct syntax to assert that the response body has a property name equal to "John" in Cypress?

easy

A. cy.request('/api/user').expect('body.name').to.equal('John')

B. cy.request('/api/user').body.should('contain', 'name', 'John')

C. cy.request('/api/user').its('body').should('have.property', 'name', 'John')

D. cy.request('/api/user').should('body.name', 'John')

Solution

1. Step 1: Review Cypress chaining syntax

   In Cypress, cy.request() returns a response object. To assert a property in the body, use its('body') to access it.

2. Step 2: Use should('have.property', key, value) for assertion

   The correct way to check a property and its value is should('have.property', 'name', 'John').

3. Final Answer:

   cy.request('/api/user').its('body').should('have.property', 'name', 'John') -> Option C

4. Quick Check:

   Use its('body').should('have.property', key, value) [OK]

Hint: Use its('body').should('have.property', key, value) for body checks [OK]

Common Mistakes:

• Trying to access body directly without its()
• Using expect() incorrectly inside cy.request chain
• Wrong method names like expect() or body.should()

3. Given the following Cypress code, what will be the result of the assertion?

cy.request('/api/data').then((response) => {
  expect(response.status).to.eq(200)
  expect(response.body.items).to.have.length(3)
})

medium

A. The test passes if the response status is 200 and items array has exactly 3 elements

B. The test fails if the response status is 200 but items array has more than 3 elements

C. The test passes regardless of the items array length

D. The test fails if the response status is not 404

Solution

1. Step 1: Analyze the status code assertion

   The code expects response.status to equal 200, so the server must respond with HTTP 200.

2. Step 2: Analyze the items array length assertion

   The code expects response.body.items to have exactly 3 elements. If it has more or less, the test fails.

3. Final Answer:

   The test passes if the response status is 200 and items array has exactly 3 elements -> Option A

4. Quick Check:

   Status 200 and items length 3 = pass [OK]

Hint: Both status and body length must match exactly for pass [OK]

Common Mistakes:

• Ignoring the length check on items array
• Confusing status 200 with 404
• Assuming partial matches pass

4. Identify the error in this Cypress test code that asserts the response body property success is true:

cy.request('/api/submit').then((response) => {
  expect(response.body.success).to.be.true()
})

medium

A. The cy.request method is missing a URL

B. The property success does not exist in response.body

C. The then callback should use response.body.success()

D. The assertion should be to.be.true without parentheses

Solution

1. Step 1: Check the assertion syntax

   In Chai assertions used by Cypress, to.be.true is a property, not a function, so it should not have parentheses.

2. Step 2: Confirm other parts are correct

   The URL is provided, and accessing response.body.success is valid if the property exists.

3. Final Answer:

   The assertion should be to.be.true without parentheses -> Option D

4. Quick Check:

   Use to.be.true without () for boolean assertions [OK]

Hint: Boolean assertions use to.be.true without parentheses [OK]

Common Mistakes:

• Adding parentheses to boolean assertions
• Assuming success is a function
• Missing URL in cy.request

5. You want to assert that the response body contains a nested object with a user's id equal to 5 and a roles array containing "admin". Which Cypress assertion correctly checks both conditions?

hard

A. cy.request('/api/user/5').its('body').should((body) => {
expect(body.id).to.eq(5)
expect(body.roles).to.include('admin')
})

B. cy.request('/api/user/5').should('body.id', 5).and('body.roles', 'admin')

C. cy.request('/api/user/5').then((response) => {
expect(response.body.id).to.equal(5)
expect(response.body.roles).to.have.length(1)
})

D. cy.request('/api/user/5').its('body').should('have.property', 'id', 5).and('have.property', 'roles', 'admin')

Solution

1. Step 1: Understand nested assertions with callback

   Using should with a callback allows multiple assertions on the body object.

2. Step 2: Check each assertion correctness

   expect(body.id).to.eq(5) checks the id correctly. expect(body.roles).to.include('admin') checks the roles array contains 'admin'.

3. Step 3: Identify incorrect options

   cy.request('/api/user/5').should('body.id', 5).and('body.roles', 'admin') uses invalid chaining syntax. cy.request('/api/user/5').then((response) => { expect(response.body.id).to.equal(5) expect(response.body.roles).to.have.length(1) }) misses checking 'admin' in roles. cy.request('/api/user/5').its('body').should('have.property', 'id', 5).and('have.property', 'roles', 'admin') wrongly checks roles as a property equal to string 'admin'.

4. Final Answer:

   cy.request('/api/user/5').its('body').should((body) => { expect(body.id).to.eq(5) expect(body.roles).to.include('admin') }) -> Option A

5. Quick Check:

   Use callback in should for multiple nested assertions [OK]

Hint: Use should callback for multiple nested property checks [OK]

Common Mistakes:

• Trying to chain multiple properties incorrectly
• Checking array length instead of content
• Using have.property with array content as string