API-first setup pattern in Cypress - Test Execution Trace

Test Overview

This test uses the API-first setup pattern to create a user via API before visiting the UI page. It verifies that the user appears correctly on the page after setup.

Test Code - Cypress

Cypress

describe('API-first setup pattern test', () => {
  it('creates user via API then verifies UI', () => {
    // Step 1: Create user via API
    cy.request('POST', '/api/users', { name: 'Alice', email: '[e-mail]' })
      .then((response) => {
        expect(response.status).to.eq(201);
        expect(response.body).to.have.property('id');
        const userId = response.body.id;

        // Step 2: Visit user page
        cy.visit(`/users/${userId}`);

        // Step 3: Verify user name on page
        cy.get('[data-cy=user-name]').should('contain.text', 'Alice');
      });
  });
});

Execution Trace - 3 Steps

Step	Action	System State	Assertion	Result
1	Send POST request to /api/users with user data {name: 'Alice', email: '[e-mail]'}	API server receives request and creates new user with unique ID	Response status is 201 Created and response body contains user ID	PASS
2	Visit the URL /users/{userId} where userId is from API response	Browser loads user detail page for the created user	—	PASS
3	Find element with data-cy attribute 'user-name' and check it contains text 'Alice'	User detail page shows user name 'Alice' in the specified element	Element text contains 'Alice'	PASS

Failure Scenario

Failing Condition: API request fails or returns status other than 201, or user name not found on UI

Execution Trace Quiz - 3 Questions

What is the first action performed in this API-first setup test?

A Send POST request to create user via API

B Visit the user detail page in browser

C Check user name on UI page

D Click a button on the page

Key Result

Using API-first setup helps tests run faster and more reliably by preparing data directly via API before UI interaction.

Practice

1. What is the main benefit of using the API-first setup pattern in Cypress tests?

easy

A. It prepares test data quickly by calling backend APIs before UI tests run.

B. It replaces UI tests completely with API tests.

C. It slows down tests by adding extra API calls.

D. It only works for frontend UI testing without backend interaction.

Solution

1. Step 1: Understand API-first setup purpose

   API-first setup means using backend API calls to prepare data before UI tests.

2. Step 2: Identify the benefit

   This approach makes tests faster and more reliable by avoiding UI data entry steps.

3. Final Answer:

   It prepares test data quickly by calling backend APIs before UI tests run. -> Option A

4. Quick Check:

   API-first setup = faster, reliable test data setup [OK]

Hint: API-first means setup via backend calls before UI tests [OK]

Common Mistakes:

• Thinking API-first replaces UI tests
• Assuming API calls slow down tests
• Believing API-first only works on frontend

2. Which of the following is the correct way to make an API call in Cypress for setup?

easy

A. cy.fetch('POST', '/users', {name: 'John'})

B. cy.api('POST', '/users', {name: 'John'})

C. cy.call('POST', '/users', {name: 'John'})

D. cy.request('POST', '/users', {name: 'John'})

Solution

1. Step 1: Recall Cypress API call syntax

   Cypress uses cy.request() to make HTTP requests.

2. Step 2: Match correct method and parameters

   cy.request('POST', url, body) is the correct syntax.

3. Final Answer:

   cy.request('POST', '/users', {name: 'John'}) -> Option D

4. Quick Check:

   Use cy.request() for API calls in Cypress [OK]

Hint: Use cy.request() for API calls in Cypress [OK]

Common Mistakes:

• Using cy.api() which is not a Cypress command
• Using cy.call() or cy.fetch() which don't exist in Cypress
• Mixing up method names or parameters

3. Given this Cypress test snippet using API-first setup:

cy.request('POST', '/api/users', {name: 'Alice'}).then((response) => {
  expect(response.status).to.eq(201)
  cy.visit('/users/' + response.body.id)
})

What will happen if the API returns status 400 instead of 201?

medium

A. The test will continue and visit the user page anyway.

B. The test will throw a syntax error.

C. The test will fail at the assertion checking response.status.

D. The test will ignore the response and pass.

Solution

1. Step 1: Analyze the assertion on response status

   The test expects response.status to equal 201.

2. Step 2: Understand behavior if status is 400

   If status is 400, the assertion expect(response.status).to.eq(201) fails and test stops with failure.

3. Final Answer:

   The test will fail at the assertion checking response.status. -> Option C

4. Quick Check:

   Assertion fails if response.status != 201 [OK]

Hint: Assertion fails if API response status is unexpected [OK]

Common Mistakes:

• Assuming test continues after failed assertion
• Thinking Cypress throws syntax error on bad status
• Believing test ignores failed API responses

4. You wrote this API-first setup code in Cypress:

cy.request('POST', '/api/items', {name: 'Book'})
  .then((res) => {
    expect(res.status).to.eq(200)
    cy.wrap(res.body.id).as('itemId')
  })
cy.get('@itemId').then((id) => {
  cy.visit(`/items/${id}`)
})

But the test fails with "Cannot read property 'then' of undefined". What is the likely cause?

medium

A. The cy.get('@itemId') runs before the alias is set.

B. The API returned status 500 causing failure.

C. The cy.request method is misspelled.

D. The cy.wrap command cannot create aliases.

Solution

1. Step 1: Understand Cypress command chaining and timing

   Cypress commands run asynchronously and in order, but alias usage requires the alias to be set before use.

2. Step 2: Identify timing issue with alias usage

   cy.get('@itemId') is called immediately, before the alias is set inside the then callback, causing undefined error.

3. Final Answer:

   The cy.get('@itemId') runs before the alias is set. -> Option A

4. Quick Check:

   Alias must be set before cy.get() uses it [OK]

Hint: Set alias before using cy.get('@alias') to avoid timing errors [OK]

Common Mistakes:

• Assuming API error causes this specific error
• Thinking cy.request is misspelled
• Believing cy.wrap cannot create aliases

5. You want to use API-first setup to create multiple users before a UI test. Which approach correctly ensures all users are created before visiting the page?

const users = [
  {name: 'Anna'},
  {name: 'Ben'},
  {name: 'Cara'}
]

// Which code snippet is correct?

hard

A. users.forEach(user => {
cy.request('POST', '/api/users', user)
cy.visit('/users')
})

B. cy.wrap(users).each(user => {
cy.request('POST', '/api/users', user)
}).then(() => {
cy.visit('/users')
})

C. for (const user of users) {
cy.request('POST', '/api/users', user)
cy.visit('/users')
}

D. cy.wrap(users).each(user => {
cy.request('POST', '/api/users', user)
})
cy.visit('/users')

Solution

1. Step 1: Understand Cypress command queue and async behavior

   Cypress commands like cy.request are asynchronous and queued. To wait for all requests, use cy.wrap().each() with a .then() callback.

2. Step 2: Analyze each option

   The native forEach and for-of options place cy.visit() inside the loop, causing visits after each request instead of after all. The cy.wrap(users).each(...) cy.visit() executes visit before requests due to queuing. Only cy.wrap(users).each(...).then(() => cy.visit()) waits for all requests before visiting.

3. Final Answer:

   cy.wrap(users).each(user => { cy.request('POST', '/api/users', user) }).then(() => { cy.visit('/users') }) -> Option B

4. Quick Check:

   Use cy.wrap().each() with then() to wait before next step [OK]

Hint: Chain .then() after cy.wrap().each() to wait for all API calls [OK]

Common Mistakes:

• Placing cy.visit() inside the forEach or for-of loop
• Using cy.wrap().each() without .then() afterward
• Not chaining .then() to wait for all iterations