cypress-book

Utilities for updating Cypress screenshots saved as repo images

Install

Assuming Cypress is a dev dependency

npm i -D cypress-book
# or
yarn add -D cypress-book

Use

Add to the Cypress plugins file

// cypress/plugins/index.js
const { registerPlugin } = require('cypress-book')

module.exports = (on, config) => {
  registerPlugin(on, config)
}

Now all screenshots captured will be copied into the images folder IF the screenshot is missing, or if the tests are running on CI and the size is different from previous.

See an example test in cypress/integration/spec.js.

The screenshot below was taking using command

cy.screenshot('hello-world', { capture: 'runner', log: false })

You can take the screenshot of the app only without the test runner UI

cy.screenshot('hello-world-page')

The screenshots are taken using cy.screenshot command.

You should commit the changed files on CI and push back to the repository. See the example GitHub Actions workflow file .github/workflows/ci.yml

Output folder

By default the images are copied to images folder. You can change the name of the output folder using Cypress environment variables. For example using the cypress.json file, we can direct the plugin to save the images in images2 folder.

{
  "env": {
    "cypress-book": {
      "imageFolder": "images2"
    }
  }
}

Instead of a single output folder, you can create folders relative to the spec file by using relative path in imageFolder value.

{
  "env": {
    "cypress-book": {
      "imageFolder": "./pics"
    }
  }
}

In the above scenario, if the specs are

cypress/
  integration/
    features/
      login-spec.js
    spec.js

And each spec saves screenshots, then they will be copied into:

cypress/
  integration/
    features/
      pics/
        screenshots ...
      login-spec.js
    picks/
      screenshots ...
    spec.js

Tolerance

Is measured using image byte sizes. You can give the tolerance to consider the images the same.

{
  "env": {
    "cypress-book": {
      "tolerance": 0.005
    }
  }
}

The above setting considers the images that are within half percent in byte size to be the same.

Exclude images

You might not want to copy every screenshot to the images folder. You can skip screenshots using their name by setting a list in the cypress.json configuration file:

{
  "env": {
    "cypress-book": {
      "excludeImages": ["social-image"]
    }
  }
}

Later on, the screenshot "social-image" will be skipped

cy.screenshot('social-image')

CLI

This package provides a script to copy a given screenshot to the destination, but only replaces the destination image if the same rules apply:

• the destination image does not exist yet
• the copy runs on CI
• the new image is different from the previous image

Use:

$ npx copy-image --source "path/to/screenshot.png" --output "path/to/image.png"

Debugging

Run the tests with DEBUG=cypress-book environment variable to see verbose log messages using debug module.

Examples

• cypress-book-todomvc
• cypress-examples

See also

• cypress-movie

Small print

Author: Gleb Bahmutov <[email protected]> © 2020

• @bahmutov
• glebbahmutov.com
• blog

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) 2020 Gleb Bahmutov <[email protected]>

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.