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title writeFile

Write to a file with the specified contents.

Syntax

cy.writeFile(filePath, contents)
cy.writeFile(filePath, contents, encoding)
cy.writeFile(filePath, contents, options)

Usage

{% fa fa-check-circle green %} Correct Usage

cy.writeFile('menu.json')

Arguments

{% fa fa-angle-right %} filePath (String)

A path to a file within the project root (the directory that contains the default cypress.json).

{% fa fa-angle-right %} contents (String, Array, or Object)

The contents to be written to the file.

{% fa fa-angle-right %} encoding (String)

The encoding to be used when writing to the file. The following encodings are supported:

  • ascii
  • base64
  • binary
  • hex
  • latin1
  • utf8
  • utf-8
  • ucs2
  • ucs-2
  • utf16le
  • utf-16le

{% fa fa-angle-right %} options (Object)

Pass in an options object to change the default behavior of cy.writeFile().

Option Default Description
log true {% usage_options log %}
flag w File system flag as used with {% url fs.writeFile https://nodejs.org/api/fs.html#fs_file_system_flags %}
encoding utf8 The encoding to be used when writing to the file

{% note info %} To use encoding with other options, have your options object be your third parameter and include encoding there. This is the same behavior as {% url fs.writeFile https://nodejs.org/api/fs.html#fs_fs_writefile_file_data_options_callback %}. {% endnote %}

Yields {% helper_icon yields %}

{% yields sets_subject cy.writeFile 'yields the value of the contents argument' %}

Examples

Text

Write some text to a txt file

If the path to the file does not exist, the file and its path will be created. If the file already exists, it will be over-written.

cy.writeFile('path/to/message.txt', 'Hello World')
cy.readFile('path/to/message.txt').then((text) => {
  expect(text).to.equal('Hello World') // true
})

{projectRoot}/path/to/message.txt will be created with the following contents:

 "Hello World"

JSON

Write JSON to a file

JavaScript arrays and objects are stringified and formatted into text.

cy.writeFile('path/to/data.json', { name: 'Eliza', email: 'eliza@example.com' })
cy.readFile('path/to/data.json').then((user) => {
  expect(user.name).to.equal('Eliza') // true
})

{projectRoot}/path/to/data.json will be created with the following contents:

{
  "name": "Eliza",
  "email": "eliza@example.com"
}

Write response data to a fixture file

cy.request('https://jsonplaceholder.typicode.com/users').then((response) => {
  cy.writeFile('cypress/fixtures/users.json', response.body)
})

// our fixture file is now generated and can be used
cy.fixture('users').then((users) => {
  expect(users[0].name).to.exist
})

Encoding

Specify the encoding as a String

cy.writeFile('path/to/ascii.txt', 'Hello World', 'ascii'))

{projectRoot}/path/to/message.txt will be created with the following contents:

Hello World

Specify the encoding as part of the options object

cy.writeFile('path/to/ascii.txt', 'Hello World', { encoding: 'ascii', flag: 'a+' })

Flags

Append contents to the end of a file

cy.writeFile('path/to/message.txt', 'Hello World', { flag: 'a+' })

Rules

Requirements {% helper_icon requirements %}

{% requirements write_file cy.writeFile %}

Assertions {% helper_icon assertions %}

{% assertions once cy.writeFile %}

Timeouts {% helper_icon timeout %}

{% timeouts automation cy.writeFile %}

Command Log

Write an array to a file

cy.writeFile('info.log', ['foo', 'bar', 'baz'])

The command above will display in the Command Log as:

{% imgTag /img/api/writefile/write-data-to-system-file-for-testing.png "Command Log writeFile" %}

When clicking on the writeFile command within the command log, the console outputs the following:

{% imgTag /img/api/writefile/console-log-shows-contents-written-to-file.png "Console Log writeFile" %}

{% history %} {% url "4.0.0" changelog#4-0-0 %} | cy.writeFile() now yields null instead of contents {% url "3.1.1" changelog#3-1-1 %} | Added flag option and appending with a+ {% url "1.0.0" changelog#1.0.0 %} | cy.writeFile() command added {% endhistory %}

See also

  • {% url cy.readFile() readfile %}