cy.readFile() assertions in Cypress - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to read a file and check its content includes 'Hello'.

Cypress

cy.readFile('example.txt').should('[1]', 'Hello')

Drag options to blanks, or click blank then click option'

Ainclude

Bcontain

Chave.text

Dequal

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'equal' instead of 'include' causes the test to fail if the content is longer.

Using 'have.text' is for DOM elements, not file content.

The should('include', 'Hello') assertion checks if the file content includes the text 'Hello'.

2fill in blank

medium

Complete the code to assert the file content equals exactly 'Test data'.

Cypress

cy.readFile('data.txt').should('[1]', 'Test data')

Drag options to blanks, or click blank then click option'

Acontain

Bequal

Cinclude

Dhave.length

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'include' or 'contain' will pass if the content has extra text.

Using 'have.length' is for checking length, not content.

The should('equal', 'Test data') assertion checks if the file content exactly matches 'Test data'.

3fill in blank

hard

Fix the error in the assertion to check the file content length is 10.

Cypress

cy.readFile('log.txt').should('have.[1]', 10)

Drag options to blanks, or click blank then click option'

Alengths

BlengthOf

Csize

Dlength

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'lengthOf' causes the test to fail because it's not a valid property.

Using 'size' or 'lengths' are invalid in this context.

The correct assertion is should('have.length', 10) to check the string length.

4fill in blank

hard

Fill both blanks to assert the file content includes 'success' and has length 5.

Cypress

cy.readFile('output.log').should('[1]', 'success').and('have.[2]', 5)

Drag options to blanks, or click blank then click option'

Ainclude

Bcontain

Clength

DlengthOf

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'contain' instead of 'include' may work but is less common here.

Using 'lengthOf' causes assertion errors.

Use should('include', 'success') to check substring and and('have.length', 5) to check length.

5fill in blank

hard

Fill all three blanks to assert the file content equals 'Done', contains 'Done', and has length 4.

Cypress

cy.readFile('status.txt').should('[1]', 'Done').and('[2]', 'Done').and('have.[3]', 4)

Drag options to blanks, or click blank then click option'

Aequal

Binclude

Clength

Dcontain

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing 'contain' and 'include' inconsistently.

Using 'lengthOf' instead of 'length' causes errors.

The first assertion checks exact equality, the second checks substring inclusion, and the third checks length.

Practice

1. What does cy.readFile() do in Cypress testing?

easy

A. Writes data to a file during the test

B. Reads the content of a file so you can check its data

C. Deletes a file from the system

D. Uploads a file to a server

Solution

1. Step 1: Understand the purpose of cy.readFile()

   This command is used to read the contents of a file during a Cypress test.

2. Step 2: Identify what cy.readFile() does not do

   It does not write, delete, or upload files; it only reads them.

3. Final Answer:

   Reads the content of a file so you can check its data -> Option B

4. Quick Check:

   cy.readFile() = Read file content [OK]

Hint: Remember: readFile reads, not writes or deletes [OK]

Common Mistakes:

• Confusing readFile with writeFile
• Thinking it uploads files
• Assuming it deletes files

2. Which of the following is the correct syntax to assert that a file contains the text "Hello World" using cy.readFile()?

easy

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

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

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

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

Solution

1. Step 1: Identify the correct assertion method for substring check

   The correct assertion to check if a string contains text is contain.

2. Step 2: Match syntax with Cypress documentation

   should('contain', 'text') is the valid syntax; others like 'equals', 'includes', or 'containText' are incorrect here.

3. Final Answer:

   cy.readFile('file.txt').should('contain', 'Hello World') -> Option D

4. Quick Check:

   Use 'contain' for substring assertions [OK]

Hint: Use 'contain' to check if file text includes a string [OK]

Common Mistakes:

• Using 'equals' instead of 'contain' for substring
• Using 'includes' which is not a Cypress assertion
• Using 'containText' which is for DOM elements

3. Given the file data.json contains {"name": "Alice", "age": 30}, what will this test assertion do?

cy.readFile('data.json').should('deep.equal', { name: 'Alice', age: 30 })

medium

A. Pass because the file content matches the object exactly

B. Fail because the object keys are strings in the file

C. Fail because 'deep.equal' cannot compare objects

D. Pass but only if the file is a string, not JSON

Solution

1. Step 1: Understand deep.equal assertion

   This assertion checks if two objects have the same structure and values deeply.

2. Step 2: Check if cy.readFile() parses JSON automatically

   Yes, it parses JSON files into objects, so the assertion compares objects correctly.

3. Final Answer:

   Pass because the file content matches the object exactly -> Option A

4. Quick Check:

   deep.equal compares objects deeply [OK]

Hint: Use deep.equal to compare JSON objects, not strings [OK]

Common Mistakes:

• Thinking file content is a string, not parsed JSON
• Confusing deep.equal with shallow equal
• Assuming keys must be non-string

4. What is wrong with this Cypress test code?

cy.readFile('log.txt').should('include', 'Error')

medium

A. The file must be JSON to use should assertions

B. The file path must be absolute, not relative

C. The assertion method should be 'contain', not 'include'

D. The method 'include' is correct and will pass if 'Error' is found

Solution

1. Step 1: Check the assertion method name

   Cypress uses 'contain' for substring assertions; 'include' is not a valid assertion method.

2. Step 2: Confirm correct assertion for substring

   The correct method is 'contain' to check if text includes a substring.

3. Final Answer:

   The assertion method should be 'contain', not 'include' -> Option C

4. Quick Check:

   Use 'contain' for substring assertions, not 'include' [OK]

Hint: Use 'contain' for substring checks, not 'include' [OK]

Common Mistakes:

• Using 'include' instead of 'contain'
• Thinking relative paths are invalid
• Assuming only JSON files can be read

5. You want to verify a downloaded CSV file contains the header row exactly as "Name,Age,Email". Which Cypress code correctly reads the file and asserts this?

hard

A. cy.readFile('downloads/data.csv').should('contain', 'Name,Age,Email')

B. cy.readFile('downloads/data.csv').should('equal', 'Name,Age,Email')

C. cy.readFile('downloads/data.csv').should('deep.equal', 'Name,Age,Email')

D. cy.readFile('downloads/data.csv').should('include', 'Name,Age,Email')

Solution

1. Step 1: Understand the file content and assertion needed

   The CSV file is text, and we want to check if it contains the exact header row as a substring.

2. Step 2: Choose the correct assertion for substring in text files

   contain is the correct assertion to check if the file text includes the header row.

3. Final Answer:

   cy.readFile('downloads/data.csv').should('contain', 'Name,Age,Email') -> Option A

4. Quick Check:

   Use 'contain' to check text includes header row [OK]

Hint: Use 'contain' to check CSV header text inside file [OK]

Common Mistakes:

• Using 'equal' which requires exact full file match
• Using 'deep.equal' which is for objects, not strings
• Using 'include' which is not a valid assertion