Reading file contents in Cypress - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

What is the output of reading a JSON file with Cypress?

Given the following Cypress test code that reads a JSON file and logs a property, what will be printed in the test runner console?

Cypress

cy.readFile('cypress/fixtures/user.json').then((user) => {
  cy.log(user.name)
})

// Assume user.json content: {"name": "Alice", "age": 30}

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

B user.name

C undefined

D Alice

💡 Hint

cy.readFile reads the file and parses JSON automatically.

cy.readFile reads the JSON file and returns the parsed object. Accessing user.name gives the string 'Alice'.

❓ assertion

intermediate

Which assertion correctly verifies file content in Cypress?

You want to check that the file 'data.txt' contains the exact text 'Hello World'. Which assertion is correct?

Cypress

cy.readFile('data.txt').should( /* assertion here */ )

A have.text('Hello World')

B contain('Hello World')

C equal('Hello World')

D include.text('Hello World')

💡 Hint

Use the assertion that checks exact equality of strings.

The 'equal' assertion checks that the file content exactly matches 'Hello World'. 'contain' checks substring, others are invalid for strings.

🔧 Debug

advanced

Why does this Cypress test fail to read the file?

Consider this test code: cy.readFile('nonexistent.json').then((data) => { cy.log(data.value) }) Why does this test fail?

Cypress

cy.readFile('nonexistent.json').then((data) => {
  cy.log(data.value)
})

A The file 'nonexistent.json' does not exist, causing an error.

B cy.log cannot log properties of objects.

C The file path is relative to the wrong folder.

D The .then callback is missing a return statement.

💡 Hint

Check if the file path is correct and file exists.

cy.readFile throws an error if the file does not exist. The test fails because 'nonexistent.json' is missing.

❓ framework

advanced

How to read a file and assert JSON property asynchronously in Cypress?

Which code snippet correctly reads 'config.json' and asserts that the 'enabled' property is true?

A cy.readFile('config.json').should('have.property', 'enabled', true)

B cy.readFile('config.json').then((config) => { expect(config.enabled).to.be.true })

C cy.readFile('config.json').should((config) => { expect(config.enabled).to.be.true })

D cy.readFile('config.json').then((config) => { assert(config.enabled === true) })

💡 Hint

Use Cypress built-in assertions for properties.

Option A uses 'should' with property check, which is the Cypress recommended way for assertions on file content.

🧠 Conceptual

expert

What is the best practice for reading large files in Cypress tests?

When reading a very large file in Cypress tests, what is the best approach to avoid slowing down tests or causing memory issues?

A Avoid reading files; instead, mock file content with fixtures.

B Split the file into smaller chunks outside Cypress and read only needed parts during tests.

C Use cy.readFile with encoding 'utf16' to reduce memory usage.

D Read the entire file with cy.readFile and process it all at once.

💡 Hint

Think about test speed and memory when handling large data.

Reading large files fully can slow tests and use much memory. Splitting files and reading only needed parts is best practice.