Add shortcuts to simplify running PHPUnit tests for standalone plugins

[felixarntz]

Summary

See #946 (comment): This PR adds shortcuts to simplify running PHPUnit tests for the new standalone plugins in a way that the new plugins only have to be added to composer.json and are then easy to test.

The way the shortcuts are defined is heavily inspired by #1002.

Usage

• composer test:auto-sizes: Tests the Auto Sizes plugin on single site.
• composer test-multisite:auto-sizes: Tests the Auto Sizes plugin on multisite.
• composer test:plugins: Tests all standalone plugins on single site.
• composer test-multisite:plugins: Tests all standalone plugins on multisite.
• composer test:all: Tests all standalone plugins plus Performance Lab on single site.
• composer test-multisite:all: Tests all standalone plugins plus Performance Lab on multisite.

There's also an NPM shortcut specifically for the GitHub workflow to test all standalone plugins:

• npm run test-php-plugins: Wraps composer test:plugins.
• npm run test-php-multisite-plugins: Wraps composer test-multisite:plugins.

Checklist

• PR has either [Focus] or Infrastructure label.
• PR has a [Type] label.
• PR has a milestone or the no milestone label.

[github-actions]

The following accounts have interacted with this PR and/or linked issues. I will continue to update these lists as activity occurs. You can also manually ask me to refresh this list by adding the props-bot label.

If you're merging code through a pull request on GitHub, copy and paste the following into the bottom of the merge commit message.

Co-authored-by: felixarntz <[email protected]>
Co-authored-by: westonruter <[email protected]>
Co-authored-by: swissspidy <[email protected]>

To understand the WordPress project's expectations around crediting contributors, please review the Contributor Attribution page in the Core Handbook.

[swissspidy]

LGTM but long term we should find something more scalable for this kind of scripts when we have more plugins.