Using fixtures in tests in Cypress - Build an Automation Script

Verify login functionality using user data from fixture

Preconditions (2)

Step 1: Open the login page at '/login'

Step 2: Load user credentials from 'user.json' fixture

Step 3: Enter the 'username' from fixture into the username input field with id 'username'

Step 4: Enter the 'password' from fixture into the password input field with id 'password'

Step 5: Click the login button with id 'loginBtn'

Step 6: Verify that the URL changes to '/dashboard' after login

✅ Expected Result: User is successfully logged in and redirected to the dashboard page

Automation Requirements - Cypress

Assertions Needed:

Verify username and password fields are filled with fixture data

Verify URL is '/dashboard' after login

Best Practices:

Use cy.fixture() to load test data

Use explicit selectors with IDs

Use cy.visit() to open pages

Use cy.url().should() for URL assertions

Avoid hardcoded waits; rely on Cypress automatic waits

Automated Solution

Cypress

describe('Login Test Using Fixture', () => {
  beforeEach(() => {
    cy.visit('/login');
  });

  it('logs in using fixture data', () => {
    cy.fixture('user').then((user) => {
      cy.get('#username').type(user.username);
      cy.get('#password').type(user.password);
      cy.get('#loginBtn').click();

      cy.url().should('include', '/dashboard');
    });
  });
});

The describe block groups the login test. The beforeEach hook opens the login page before each test to ensure a fresh start.

Inside the test, cy.fixture('user') loads the user data from the user.json file. The then callback receives the user object.

We use cy.get('#username') and cy.get('#password') to find input fields by their IDs and type the fixture data into them.

Clicking the login button triggers the login action.

Finally, cy.url().should('include', '/dashboard') asserts that the URL contains '/dashboard', confirming successful login.

This approach uses best practices: clear selectors, fixture data loading, and Cypress automatic waits.

Common Mistakes - 3 Pitfalls

Hardcoding user credentials directly in the test code

Using slow fixed waits like cy.wait(5000) instead of relying on Cypress automatic waits

{'mistake': "Using vague selectors like cy.get('input') instead of specific IDs or data attributes", 'why_bad': 'Vague selectors can select wrong elements and break tests if UI changes.', 'correct_approach': 'Use unique IDs or data-cy attributes for stable selectors.'}

Bonus Challenge

Now add data-driven testing with 3 different user credentials from a fixture array

Show Hint

Practice

1. What is the main purpose of using fixtures in Cypress tests?

easy

A. To load external static data files for use in tests

B. To create dynamic test data during test execution

C. To define custom commands for repeated actions

D. To configure browser settings before tests run

Solution

1. Step 1: Understand what fixtures are

   Fixtures are files that hold static data like JSON or text files used in tests.

2. Step 2: Identify their purpose in Cypress

   They help load this external data into tests to simulate real data inputs or responses.

3. Final Answer:

   To load external static data files for use in tests -> Option A

4. Quick Check:

   Fixtures = external static data [OK]

Hint: Fixtures hold static test data files for easy reuse [OK]

Common Mistakes:

• Thinking fixtures create dynamic data
• Confusing fixtures with custom commands
• Assuming fixtures configure browser settings

2. Which of the following is the correct syntax to load a fixture named user.json in a Cypress test?

easy

A. cy.readFile('user.json').then((data) => { ... })

B. cy.loadFixture('user.json').then((data) => { ... })

C. cy.fixture('user.json').then((data) => { ... })

D. cy.getFixture('user.json').then((data) => { ... })

Solution

1. Step 1: Recall the Cypress fixture command

   The correct command to load fixture data is cy.fixture().

2. Step 2: Match the syntax with the options

   cy.fixture('user.json').then((data) => { ... }) uses cy.fixture('user.json').then((data) => { ... }), which is correct syntax.

3. Final Answer:

   cy.fixture('user.json').then((data) => { ... }) -> Option C

4. Quick Check:

   Use cy.fixture() to load fixture files [OK]

Hint: Use cy.fixture() to load fixture files [OK]

Common Mistakes:

• Using non-existent commands like cy.loadFixture or cy.getFixture
• Confusing cy.readFile with cy.fixture
• Omitting the .then() to access data

3. Given the fixture file user.json contains { "name": "Alice", "age": 30 }, what will the following Cypress code print?

cy.fixture('user.json').then((user) => {
  cy.log(`Name: ${user.name}, Age: ${user.age}`)
})

medium

A. SyntaxError due to template string

B. Name: undefined, Age: undefined

C. Name: user.name, Age: user.age

D. Name: Alice, Age: 30

Solution

1. Step 1: Understand fixture data loading

   The fixture loads JSON data with keys "name" and "age" correctly.

2. Step 2: Analyze the template string usage

   The template string uses ${user.name} and ${user.age} to insert values.

3. Final Answer:

   Name: Alice, Age: 30 -> Option D

4. Quick Check:

   Fixture data accessed correctly = prints values [OK]

Hint: Template strings insert fixture data values directly [OK]

Common Mistakes:

• Expecting undefined because of async confusion
• Misreading template string syntax
• Assuming fixture data keys are different

4. What is wrong with this Cypress test code snippet that tries to use fixture data?

cy.fixture('data.json').then((data) => {
  cy.get('#name').type(data.name)
})
cy.get('#submit').click()

medium

A. The cy.get('#submit').click() runs before fixture loads

B. The fixture file name is incorrect

C. The type() command is invalid

D. Missing assertion after typing

Solution

1. Step 1: Check command chaining and timing

   The cy.get('#submit').click() runs immediately, not waiting for fixture to load.

2. Step 2: Understand Cypress command queue

   Commands outside the then() run before the fixture data is ready, causing timing issues.

3. Final Answer:

   The cy.get('#submit').click() runs before fixture loads -> Option A

4. Quick Check:

   Commands must chain to wait for fixture data [OK]

Hint: Chain commands inside .then() to ensure order [OK]

Common Mistakes:

• Placing commands outside fixture .then() causing race conditions
• Assuming fixture loads instantly
• Ignoring Cypress command queue behavior

5. You want to use a fixture named profile.json in multiple tests inside a describe block. Which is the best way to load it once and reuse the data in all tests?

hard

A. Load fixture inside each it() test separately

B. Use before() hook to load fixture and assign to this context

C. Use cy.readFile() in each test to read the fixture

D. Import the fixture JSON file directly using import statement

Solution

1. Step 1: Understand fixture reuse in Cypress

   Loading fixture once in before() hook improves efficiency and shares data.

2. Step 2: Assign fixture data to this context

   Using function() syntax allows this.data access in tests.

3. Final Answer:

   Use before() hook to load fixture and assign to this context -> Option B

4. Quick Check:

   before() loads fixture once for all tests [OK]

Hint: Load fixture once in before() and save to this [OK]

Common Mistakes:

• Loading fixture repeatedly in each test wasting time
• Using arrow functions preventing this context access
• Confusing cy.readFile with cy.fixture for fixtures