cy.readFile() assertions in Cypress - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does cy.readFile() do in Cypress?

cy.readFile() reads the contents of a file from the file system during a test.

It allows you to check file content as part of your test assertions.

beginner

How do you assert that a file contains specific text using cy.readFile()?

Use cy.readFile('path/to/file').should('include', 'expected text').

This checks that the file content includes the given text.

intermediate

How can you assert JSON content from a file using cy.readFile()?

Read the JSON file and assert its properties like this:

cy.readFile('data.json').should((json) => {<br>  expect(json.key).to.equal('value');<br>})

beginner

What happens if cy.readFile() tries to read a non-existent file?

The test will fail with an error saying the file was not found.

This helps catch missing or wrongly named files during testing.

intermediate

Why is it better to use should() assertions with cy.readFile() instead of then()?

should() retries automatically until the assertion passes or times out.

This makes tests more stable if the file content changes asynchronously.

What does cy.readFile('file.txt').should('include', 'hello') check?

A The file path exists

B The file contains the text 'hello'

C The file size is greater than zero

D The file is empty

This assertion checks that the file content includes the string 'hello'.

How do you assert a JSON file has a key 'name' with value 'Alice' using cy.readFile()?

A cy.readFile('file.json').should((json) => { expect(json.name).to.equal('Alice') })

B cy.readFile('file.json').should('include', 'Alice')

C cy.readFile('file.json').should('have.property', 'name', 'Alice')

D cy.readFile('file.json').then(json => json.name === 'Alice')

Option A uses a callback to assert the JSON property value correctly.

What happens if cy.readFile() tries to read a missing file?

A The test passes silently

B The test retries reading forever

C The test fails with a file not found error

D The test skips the file check

Cypress fails the test with an error if the file does not exist.

Why prefer should() over then() for assertions on cy.readFile()?

A <code>then()</code> cannot access file content

B <code>then()</code> retries the assertion automatically

C <code>should()</code> runs faster than <code>then()</code>

D <code>should()</code> retries the assertion until it passes or times out

should() retries assertions, making tests more stable with dynamic content.

Which is a valid way to check that a file contains the exact text 'Hello World'?

A cy.readFile('file.txt').should('equal', 'Hello World')

B cy.readFile('file.txt').should('include', 'Hello')

C cy.readFile('file.txt').should('contain', 'World')

D cy.readFile('file.txt').should('have.length', 11)

Using should('equal', 'Hello World') asserts the file content exactly matches the string.

Explain how to use cy.readFile() to verify JSON file content in a Cypress test.

Think about how to access JSON keys and check their values.

Describe the benefits of using should() assertions with cy.readFile() instead of then().

Consider what happens if the file content changes after the first read.