Add Chrome for Testing to cypress/factory build process

[MikeMcC399]

What would you like?

Add an option to install the Google Chrome for Testing browser using the cypress/factory build process.

Why is this needed?

Currently the cypress/factory build process supports the installation of Google Chrome by specifying CHROME_VERSION. It does not support Chrome for Testing.

Cypress introduced support for Chrome for Testing in cypress@13.17.0.

Google has restricted the use of the --load-extension flag in Chrome version 137 and above and continues to allow its use in Chrome for Testing. See also cypress@14.4.0 changelog.

The directory examples/chrome-for-testing shows how to add Chrome for Testing to a custom Cypress Docker image. This is however less convenient than support in cypress/factory would be.

[MikeMcC399]

Background

Google

• Google Chrome for Testing was introduced with Chrome release 113 (May 2023)
• Google restricted the use of the --load-extension flag in Chrome version 137 and above, and continues to allow the use of the flag in Chrome for Testing. See also cypress@14.4.0 changelog.

The Chrome for Testing article describes How can I get Chrome for Testing binaries? with options:

• use the npm package @puppeteer/browsers command-line utility
• use JSON API endpoints

The Chrome for Testing availability dashboard provides an overview. A typical download location for Linux is as follows. This is a zip file, not a Debian package.

https://storage.googleapis.com/chrome-for-testing-public/137.0.7151.68/linux64/chrome-linux64.zip

Cypress

• Cypress introduced support for Chrome for Testing in cypress@13.17.0
• Cypress supports both Chrome and Chrome for Testing, and treats them as separate browsers. See Launching Browsers - Chrome requiring --browser chrome and --browser chrome-for-testing respectively to launch.
• The Cypress.io team expects that the removal of the --load-extension flag in Chrome does not affect most Cypress users.

Cypress Docker images

• The reasons that Google quote for introducing Google Chrome for Testing are already solved by Cypress Docker image support for Chrome:
  • access to specific Chrome versions
  • fixed Chrome version (no auto update)
• Cypress Docker images cypress/browsers and cypress/included include Chrome, Edge and Firefox, not Chrome for Testing
• The size of the current cypress/browsers image is 881 MB compressed on Docker Hub (2.36GB uncompressed)
• The Cypress Docker image process cypress/factory does not currently support Chrome for Testing
• The examples/chrome-for-testing directory provides an example of how to add Chrome for Testing to a cypress/base Docker image, using the @puppeteer/browsers command-line utility and producing a custom Docker image

Assessment

• Chrome for Testing could be optionally built into a Docker image using a simple parameter such as CHROME_FOR_TESTING_VERSION.

• Chrome for Testing is not a drop-in replacement for Chrome. There are now differences in functionality and Cypress treats them as two distinct browsers.

• Adding Chrome for Testing alongside Chrome in cypress/factory doubles the related handling necessary in terms of build, test and documentation items for Chrome flavored browsers

• If, in a second step, Chrome for Testing is also added by default to the standard images cypress/browsers and cypress/included, each image size would be significantly increased. For cypress/browsers the size would increase by an estimated 40% (365 MB compressed) on Docker Hub.

• Completely replacing Chrome with Chrome for Testing in cypress/factory and in standard images cypress/browsers and cypress/included would be a breaking change.

• For the download alternatives: using @puppeteer/browsers command-line utility has the advantage of allowing download by alias, such as stable, beta, and by major version, such as 137, however this requires additional 36MB download for the package and its dependencies. Installation of required Debian dependencies is not handled cleanly and needs to be added separately. Using a direct download of an exact version of Chrome for Testing fits in more with the scheme for other build options like CHROME_VERSION and requires only wget amd unzip, which are already available.

Recommendation

• Adding Chrome for Testing to the cypress/factory process provides a simplification for users wanting to create a custom image containing Chrome for Testing. Instead of adding a script to their Dockerfile, they would just add the parameter CHROME_FOR_TESTING_VERSION.

• Use direct download not @puppeteer/browsers command-line utility. An example using @puppeteer/browsers can be left in the examples/chrome-for-testing directory.

• If Chrome for Testing needs to be added to standard images cypress/browsers and cypress/included, then this enhancement would be a prerequisite.

• At this time, it does not seem advisable to include Chrome for Testing in standard images cypress/browsers and cypress/included due to size impact. Any on-going need for inclusion should be monitored.

[MikeMcC399]

@jennifer-shehane / @AtofStryker

If the Cypress.io team would like this suggestion implemented

• to add the capability of selecting Chrome for Testing in the cypress/factory process

then I will submit a PR.

[MikeMcC399]

• PR feat: add Chrome for Testing to cypress/factory build process #1371 submitted to implement this suggestion