JSON fixture files in Cypress - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of this Cypress test using a JSON fixture?

Given the fixture file user.json contains {"name": "Alice", "age": 30}, what will be logged by this test?

Cypress

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

A Name: Alice, Age: 30

B Name: undefined, Age: undefined

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

D SyntaxError: Unexpected token

💡 Hint

Remember that cy.fixture loads the JSON content and passes it as an object.

The fixture file is loaded and parsed as an object. The user parameter contains the JSON data, so accessing user.name and user.age returns the correct values.

❓ assertion

intermediate

Which assertion correctly verifies the loaded JSON fixture data?

Assuming user.json contains {"name": "Bob", "active": true}, which assertion correctly checks that the user is active?

Cypress

cy.fixture('user.json').then((user) => {
  // Assertion here
})

A expect(user.active).to.be('true')

B expect(user.active).to.equal('true')

C expect(user.active).to.be.false

D expect(user.active).to.be.true

💡 Hint

Check the data type of the active property in the JSON.

The active property is a boolean true, so the assertion should check for boolean true, not string 'true'.

🔧 Debug

advanced

Why does this Cypress test fail to load the fixture?

The test code is:

cy.fixture('data.json').then((data) => {
  expect(data.items.length).to.equal(3)
})

The fixture file data.json exists but the test fails with TypeError: Cannot read property 'length' of undefined. What is the most likely cause?

A The fixture file name is misspelled in the test code.

B The JSON file does not have an <code>items</code> property at the root level.

C The <code>then</code> callback is missing a parameter.

D The test is missing <code>cy.visit()</code> before loading the fixture.

💡 Hint

Check the structure of the JSON file and the property being accessed.

The error means data.items is undefined, so the JSON does not contain an items property at the root. The test tries to access length of undefined, causing the error.

❓ framework

advanced

How does Cypress handle fixture file caching during tests?

Which statement best describes Cypress's behavior with fixture files when running multiple tests?

A Cypress reloads the fixture file from disk every time <code>cy.fixture()</code> is called.

B Cypress requires manual cache clearing to reload fixture files between tests.

C Cypress caches fixture files after the first load to improve performance in subsequent tests.

D Cypress does not support caching fixture files and always fetches them from the server.

💡 Hint

Think about how test runners optimize repeated file access.

Cypress caches fixture files after the first load to speed up tests by avoiding repeated disk reads.

🧠 Conceptual

expert

What is the best practice for managing large JSON fixture files in Cypress tests?

You have a large JSON fixture file with thousands of entries. Which approach is best to keep tests fast and maintainable?

A Split the large JSON into smaller fixture files and load only needed parts in each test.

B Load the entire large JSON fixture in every test to ensure consistency.

C Convert the JSON fixture into a JavaScript file and import it directly in tests.

D Avoid using fixtures and hardcode test data inside each test instead.

💡 Hint

Think about test speed and data relevance.

Splitting large fixtures into smaller files and loading only necessary data reduces memory use and speeds up tests.

Practice

1. What is the main purpose of using JSON fixture files in Cypress tests?

easy

A. To store test data separately from test code for easy reuse

B. To write test assertions directly inside the JSON file

C. To configure Cypress plugins and environment variables

D. To define custom commands for Cypress tests

Solution

1. Step 1: Understand fixture file role

   Fixture files hold static data like user info or responses to use in tests.

2. Step 2: Identify purpose in Cypress

   They separate test data from code, making tests cleaner and reusable.

3. Final Answer:

   To store test data separately from test code for easy reuse -> Option A

4. Quick Check:

   Fixture files = test data storage [OK]

Hint: Fixtures hold test data, not code or configs [OK]

Common Mistakes:

• Thinking fixtures contain test logic
• Confusing fixtures with config files
• Using fixtures to write assertions

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

easy

A. cy.getFixture('user.json').then((data) => { /* use data */ })

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

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

D. cy.readFile('user.json').then((data) => { /* use data */ })

Solution

1. Step 1: Recall Cypress fixture command

   Cypress uses cy.fixture() to load fixture files from the fixtures folder.

2. Step 2: Check method names

   Only cy.fixture() is the correct Cypress command; others do not exist or are incorrect.

3. Final Answer:

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

4. Quick Check:

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

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

Common Mistakes:

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

3. Given the fixture file user.json with content:

{"name": "Alice", "age": 30}

What will the following Cypress code print to the console?

cy.fixture('user.json').then((user) => {
  console.log(user.name);
  console.log(user.age + 5);
})

medium

A. "user" and 35

B. "Alice" and 35

C. "Alice" and "35"

D. undefined and NaN

Solution

1. Step 1: Understand fixture data structure

   The JSON has keys "name" with value "Alice" and "age" with value 30 (number).

2. Step 2: Analyze console.log statements

   First logs user.name which is "Alice". Second logs user.age + 5, which is 30 + 5 = 35.

3. Final Answer:

   "Alice" and 35 -> Option B

4. Quick Check:

   Access JSON keys correctly = "Alice" and 35 [OK]

Hint: JSON values keep their types; numbers add normally [OK]

Common Mistakes:

• Treating numbers as strings and concatenating
• Using wrong keys or misspelling
• Expecting undefined from valid fixture keys

4. You wrote this Cypress test code to load a fixture:

cy.fixture('config.json').then((config) => {
  expect(config.timeout).to.equal(5000)
})

But the test fails with TypeError: Cannot read property 'timeout' of undefined. What is the most likely cause?

medium

A. The then callback is missing a parameter

B. The expect syntax is incorrect

C. The fixture file contains invalid JSON syntax

D. The fixture file config.json does not exist or is misnamed

Solution

1. Step 1: Analyze error message

   The error says config is undefined, so config.timeout fails.

2. Step 2: Check fixture loading causes

   If the fixture file is missing or misnamed, cy.fixture() returns undefined, causing this error.

3. Final Answer:

   The fixture file config.json does not exist or is misnamed -> Option D

4. Quick Check:

   Missing fixture file = undefined data [OK]

Hint: Check fixture file name and location first [OK]

Common Mistakes:

• Assuming expect syntax causes undefined error
• Ignoring fixture file path or name typos
• Not validating JSON file existence

5. You have a fixture file users.json containing an array of user objects:

[{"id":1,"name":"Bob"},{"id":2,"name":"Carol"},{"id":3,"name":"Dave"}]

How can you write a Cypress test to check that the user with id 2 has the name "Carol"?

hard

A. cy.fixture('users.json').then(users => { expect(users.find(u => u.id === 2).name).to.equal('Carol') })

B. cy.fixture('users.json').then(users => { expect(users[2].name).to.equal('Carol') })

C. cy.fixture('users.json').then(users => { expect(users.id === 2).to.equal('Carol') })

D. cy.fixture('users.json').then(users => { expect(users.name).to.include('Carol') })

Solution

1. Step 1: Understand fixture data structure

   The fixture is an array of objects, each with id and name.

2. Step 2: Find user with id 2 and check name

   Use find() to get the user object where id === 2, then check its name.

3. Final Answer:

   cy.fixture('users.json').then(users => { expect(users.find(u => u.id === 2).name).to.equal('Carol') }) -> Option A

4. Quick Check:

   Use find() to locate object by id [OK]

Hint: Use array.find() to locate object by property [OK]

Common Mistakes:

• Using wrong array index instead of find()
• Comparing id directly to name
• Accessing properties on the whole array