Why File upload (cy.selectFile) in Cypress? - Purpose & Use Cases

The Big Idea

What if you could test file uploads in seconds instead of minutes, every time without mistakes?

The Scenario

Imagine you have a website where users must upload their profile pictures. You try to test this by manually clicking the upload button, selecting files one by one, and checking if the upload works every time.

The Problem

This manual testing is slow and tiring. You might miss errors or forget to try different file types. It's easy to make mistakes or skip important checks because it takes too much time and effort.

The Solution

Using cy.selectFile in Cypress lets you automate file uploads easily. You can quickly simulate selecting files in your tests, making your checks fast, repeatable, and reliable without clicking around manually.

Before vs After

✗ Before

cy.get('input[type=file]').click(); // manually select file in dialog

✓ After

cy.get('input[type=file]').selectFile('cypress/fixtures/photo.png');

What It Enables

Automated file uploads let you test many file types and scenarios quickly, ensuring your app handles uploads correctly every time.

Real Life Example

For example, an online job application site needs to accept resumes in PDF or DOCX format. Automated tests with cy.selectFile can verify uploads for all supported formats without manual effort.

Key Takeaways

Manual file upload testing is slow and error-prone.

cy.selectFile automates file selection in tests.

This makes upload testing fast, reliable, and repeatable.

Practice

1. What is the primary purpose of cy.selectFile in Cypress testing?

easy

A. To simulate a user selecting a file for upload in a test

B. To download files from the server during a test

C. To delete files from the local system during a test

D. To open a file in the browser for viewing

Solution

1. Step 1: Understand the role of cy.selectFile

   This command is designed to simulate a user action of selecting a file in a file input element during automated tests.

2. Step 2: Compare options with this purpose

   Options B, C, and D describe actions unrelated to file selection for upload, such as downloading, deleting, or opening files, which cy.selectFile does not do.

3. Final Answer:

   To simulate a user selecting a file for upload in a test -> Option A

4. Quick Check:

   File selection = Simulate user upload [OK]

Hint: Remember: selectFile mimics user file selection [OK]

Common Mistakes:

• Confusing file upload with file download
• Thinking selectFile deletes files
• Assuming selectFile opens files in browser

2. Which of the following is the correct syntax to select a file named example.txt using cy.selectFile?

easy

A. cy.get('input[type=file]').selectFile('example.txt')

B. cy.get('input[type=file]').selectFile({ contents: 'example.txt' })

C. cy.get('input[type=file]').selectFile('file://example.txt')

D. cy.get('input[type=file]').selectFile('cypress/fixtures/example.txt')

Solution

1. Step 1: Understand file path usage in cy.selectFile

   The file path should point to the test fixture location, usually inside the cypress/fixtures folder.

2. Step 2: Evaluate each option's path

   cy.get('input[type=file]').selectFile('cypress/fixtures/example.txt') correctly uses the relative path to the fixture file. cy.get('input[type=file]').selectFile('example.txt') uses just the filename without path, which won't work. cy.get('input[type=file]').selectFile({ contents: 'example.txt' }) incorrectly uses an object with contents as string. cy.get('input[type=file]').selectFile('file://example.txt') uses an invalid file URI.

3. Final Answer:

   cy.get('input[type=file]').selectFile('cypress/fixtures/example.txt') -> Option D

4. Quick Check:

   Use fixture path for selectFile [OK]

Hint: Use fixture folder path for files in selectFile [OK]

Common Mistakes:

• Using only filename without path
• Passing file contents as string instead of path
• Using invalid file URI scheme

3. Given the following Cypress code snippet, what will be the result of the test?

cy.get('input[type=file]').selectFile('cypress/fixtures/photo.png')
  .should('have.prop', 'files').then(files => {
    expect(files[0].name).to.equal('photo.png')
  })

medium

A. The test will pass because the file name matches

B. The test will fail because the file input does not have files property

C. The test will throw a syntax error due to incorrect chaining

D. The test will pass but the file name will be undefined

Solution

1. Step 1: Understand selectFile and file input properties

   After selecting a file, the input element's files property contains the selected files. Accessing files[0].name should give the file name.

2. Step 2: Analyze the assertion

   The assertion checks if the first file's name equals 'photo.png', which matches the selected file. This is valid and should pass.

3. Final Answer:

   The test will pass because the file name matches -> Option A

4. Quick Check:

   File name check = Pass [OK]

Hint: Files property holds selected files; check name to verify [OK]

Common Mistakes:

• Assuming files property is missing
• Confusing syntax chaining in Cypress
• Expecting undefined file name

4. You wrote this Cypress test to upload a file but it fails:

cy.get('#fileInput').selectFile('example.pdf')

What is the most likely reason for the failure?

medium

A. The selector '#fileInput' is invalid syntax

B. The file path is incorrect or missing the fixture folder

C. selectFile cannot be used on input elements

D. The file must be uploaded manually, not via tests

Solution

1. Step 1: Check file path requirements for selectFile

   The file path must be relative to the cypress/fixtures folder or an absolute path. Just 'example.pdf' without path likely causes failure.

2. Step 2: Verify other options

   Selector syntax '#fileInput' is valid. selectFile works on input elements. Manual upload is not required in tests.

3. Final Answer:

   The file path is incorrect or missing the fixture folder -> Option B

4. Quick Check:

   File path must include fixture folder [OK]

Hint: Always include fixture folder in file path [OK]

Common Mistakes:

• Using filename without path
• Thinking selector syntax is wrong
• Believing selectFile can't upload files

5. You want to test uploading multiple files at once using cy.selectFile. Which code snippet correctly uploads two files named doc1.pdf and image1.png located in the fixtures folder?

hard

A. cy.get('input[type=file]').selectFile({ files: ['doc1.pdf', 'image1.png'] })

B. cy.get('input[type=file]').selectFile('cypress/fixtures/doc1.pdf, cypress/fixtures/image1.png')

C. cy.get('input[type=file]').selectFile(['cypress/fixtures/doc1.pdf', 'cypress/fixtures/image1.png'])

D. cy.get('input[type=file]').selectFile(['doc1.pdf', 'image1.png'])

Solution

1. Step 1: Understand multiple file upload syntax

   cy.selectFile accepts an array of file paths to upload multiple files. Each path must be relative to the fixtures folder or absolute.

2. Step 2: Evaluate each option

   cy.get('input[type=file]').selectFile(['cypress/fixtures/doc1.pdf', 'cypress/fixtures/image1.png']) correctly provides an array with full fixture paths. cy.get('input[type=file]').selectFile('cypress/fixtures/doc1.pdf, cypress/fixtures/image1.png') uses a single string with comma-separated paths, which is invalid. cy.get('input[type=file]').selectFile({ files: ['doc1.pdf', 'image1.png'] }) uses an object with files array but missing paths. cy.get('input[type=file]').selectFile(['doc1.pdf', 'image1.png']) uses array without fixture folder path, which will fail.

3. Final Answer:

   cy.get('input[type=file]').selectFile(['cypress/fixtures/doc1.pdf', 'cypress/fixtures/image1.png']) -> Option C

4. Quick Check:

   Array of fixture paths = Correct multiple upload [OK]

Hint: Use array of full fixture paths for multiple files [OK]

Common Mistakes:

• Passing comma-separated string instead of array
• Omitting fixture folder in paths
• Using object without correct file paths