cypress-log-to-term

cypress-log-to-term

Overwrite the cy.log command to print to both the Command Log and to the terminal

Explanation

Read the blog post Two Simple Tricks To Make Your Cypress Tests Better. This plugin is covered in my Cypress Plugins course 🎓:

• Lesson a3: Log the messages from the test to the terminal
• Lesson a4: Log the messages using the plugin cypress-log-to-term

Install

Install this plugin from the NPM registry using NPM or Yarn or your favorite Node package manager.

# Install using NPM
$ npm i -D cypress-log-to-term
# Install using Yarn
$ yarn add -D cypress-log-to-term

Include the plugin from your support or spec file

// cypress/e2e/spec.cy.js
// https://github.com/bahmutov/cypress-log-to-term
import 'cypress-log-to-term/commands'

Include the plugin from your cypress.config.js file's setupNodeEvents callback

// cypress.config.js
const { defineConfig } = require('cypress')

module.exports = defineConfig({
  e2e: {
    // baseUrl, etc
    supportFile: false,
    fixturesFolder: false,
    setupNodeEvents(on, config) {
      // register the "cypress-log-to-term" plugin
      // https://github.com/bahmutov/cypress-log-to-term
      // IMPORTANT: pass the "on" callback argument
      require('cypress-log-to-term')(on)
    },
  },
})

See cypress/e2e/spec.cy.js

Markdown

Markdown bold characters ** are automatically removed before passing them to the task to be printed.

Yields the current subject

The cy.log yields the current subject to the next command, because it should.

cy.wrap(42).log().should('equal', 42)

Format string

This plugins adds format string and format callback function feature to the cy.log command. For example, the "standard" cy.log command could only print a string argument

cy.wrap({ name: 'Joe' }).log('the name')
// prints "the name"

This module allows you to print the current subject

cy.wrap({ name: 'Joe' }).log()
// prints '{"name":"Joe"}'

Complex objects are supported

cy.wrap([1, 'hello', { name: 'Joe' }]).log()
// prints '[1,"hello",{"name":"Joe"}]'

You can add a string argument and insert the formatted subject into it

cy.wrap({ name: 'Joe' }).log('person is %o')
// prints 'person is {"name":"Joe"}'

This is equivalent to {0} notation

cy.wrap({ name: 'Joe' }).log('person is {0}')
// prints 'person is {"name":"Joe"}'

You can even access the properties of the subject

cy.wrap({ name: 'Joe' }).log('my name is {0.name}')
// prints 'my name is Joe'

Deep properties are allowed

cy.wrap([{ name: 'Joe' }, { name: { first: 'Anna' } }])
  // from the subject (accessed via {0})
  // grab the property "1" (which is the second item in our array)
  // then grab the path "name.first"
  .log('her name is {0.1.name.first}')
// prints 'her name is Anna'

Format callback

You can pass a callback function to the overwritten cy.log command. This way you can return a formatted string given the subject value.

const person = { name: 'Joe' }
cy.wrap(person).log((p) => `name is ${p.name}`)
// prints 'name is Joe'
cy.wrap([1, 2, 3]).log((list) => list[1])
// prints "2"

If you return non-string result, cy.log will try its best to serialize it

cy.wrap({ name: 'Me' }).log((x) => x) // {"name":"Me"}

Circular objects

If the subject to be serialized has circular references, they are safely converted to string

const obj = {
  name: 'object',
}
obj.next = obj
// try to log a circular object
cy.wrap(obj, { log: false }).log()
// {"name":"object","next":"[Circular]"}

See circular.cy.js

jQuery / DOM elements

Are serialized with main properties (id, class, attributes) and the number of matched elements

<h1 id="title">Hello</h1>

cy.get('h1').log()
// $ of 1 <div#obj.my-object/>

If there are a lot of yielded elements, only the first and the last one are logged

<ol id="people">
  <li class="first">one</li>
  <li>two</li>
  <li>three</li>
  <li>four</li>
  <li class="last">five</li>
</ol>

cy.get('#people li').log()
// $ of 5 [<li.first/>...<li.last/>]

Note: when serializing, the log respects the chai.config.truncateThreshold setting. To log more info, increase it in your spec or support file:

<p class="some-class" data-cy="para" data-test="my-p">Test page</p>

cy.get('#people li').log()
// default
// $ of 1 <p.some-class data-cy=para data-t...
// with chai.config.truncateThreshold = 200
// $ of 1 <p.some-class data-cy=para data-test=my-p/>

Tip: use the format string to better explain what the elements are

cy.get('#people li').log('list of people %o')
// list of people $ of 5 [<li.first/>...<li.last/>]

See dom.cy.js

Types

This package includes TypeScript command definitions for its custom commands in the file src/index.d.ts. To use it from your JavaScript specs:

/// <reference types="cypress-log-to-term" />

If you are using TypeScript, include this module in your types list

{
  "compilerOptions": {
    "types": ["cypress", "cypress-log-to-term"]
  }
}

Small print

Author: Gleb Bahmutov <[e-mail]> © 2022

• @bahmutov
• glebbahmutov.com
• blog
• videos
• presentations
• cypress.tips
• Cypress Tips & Tricks newsletter

License: MIT - do anything with the code, but don't blame me if it does not work.

Support: if you find any problems with this module, email / tweet / open issue on Github

MIT License

Copyright (c) 2022 Gleb Bahmutov <[e-mail]>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.