API-first setup pattern in Cypress - Build an Automation Script

Create a new user via API and verify UI shows the user

Preconditions (3)

Step 1: Send a POST request to /api/users with JSON body {"name": "Alice", "email": "[e-mail]"}

Step 2: Open the /users page in the browser

Step 3: Verify that the user list contains a user with name 'Alice' and email '[e-mail]'

✅ Expected Result: The new user 'Alice' is created via API and visible in the UI user list

Automation Requirements - Cypress

Assertions Needed:

Verify API response status is 201

Verify UI user list contains the created user with correct name and email

Best Practices:

Use API call to set up test data before UI visit

Use explicit assertions on API response

Use data-test attributes for UI element selectors

Avoid UI actions for setup to speed up tests

Automated Solution

Cypress

describe('API-first setup pattern test', () => {
  it('creates a user via API and verifies UI shows it', () => {
    // Step 1: Create user via API
    cy.request({
      method: 'POST',
      url: '/api/users',
      body: { name: 'Alice', email: '[e-mail]' },
      headers: { 'Content-Type': 'application/json' }
    }).then((response) => {
      expect(response.status).to.equal(201);
      expect(response.body).to.have.property('id');
    });

    // Step 2: Visit the users page
    cy.visit('/users');

    // Step 3: Verify the user appears in the list
    cy.get('[data-test=user-list]').should('be.visible');
    cy.get('[data-test=user-list]').contains('Alice').should('exist');
    cy.get('[data-test=user-list]').contains('[e-mail]').should('exist');
  });
});

This test uses Cypress to automate the manual test case.

First, it sends a POST request to the API to create a user named Alice. We check the response status is 201 to confirm success and that the response body contains an id, meaning the user was created.

Next, the test visits the /users page in the browser to check the UI.

Finally, it looks for the user list element using a data-test attribute, which is a best practice for stable selectors. It asserts that the list contains the name 'Alice' and the email '[e-mail]'.

This approach uses the API to set up test data quickly and reliably, then verifies the UI shows the expected result, following the API-first setup pattern.

Common Mistakes - 4 Pitfalls

Setting up test data only through the UI instead of API

Not asserting the API response status or body

Using brittle selectors like CSS classes or element indexes for UI verification

{'mistake': 'Not waiting for the UI to load before checking elements', 'why_bad': 'Tests may fail intermittently if elements are not yet rendered.', 'correct_approach': "Use Cypress commands like cy.get() with should('be.visible') to wait for elements."}

Bonus Challenge

Now add data-driven testing with 3 different users created via API and verify each appears in the UI

Show Hint

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