How can I remove test directories when deploying?

When deploying Drupal, there are a lot of files in test directories, none of which are needed in a production environment. There's an ongoing issue to Exclude test files from release packages, but how can I get rid of the test files now?

After trying to configure drupal-core-vendor-hardening to do this, I realized that it's too much of a pain to add each individual module.

So I wrote a simple bash script instead.

cd "$my_git_root"
# Delete Drupal test directories.
# https://unix.stackexchange.com/a/89937
find . -type d -name tests -exec rm -rf {} +
# Delete testing and demo profiles.
find web/core/profiles -type d -name 'testing*' -exec rm -rf {} +
find web/core/profiles -type d -name 'nightwatch_testing' -exec rm -rf {} +
find web/core/profiles -type d -name 'demo_umami' -exec rm -rf {} +
# Delete README files.
find . -type f -name 'README*' -delete
find . -type f -name 'CHANGELOG*' -delete
# Delete patch records.
find . -type f -name 'PATCHES.txt' -delete
# Delete markdown files except licenses.
find web -type f -name "*.md" -not -name "LICENSE*" -delete
# Delete txt files except licenses.
find web -type f -name "*.txt" -not -name "LICENSE*" -not -name "COPYRIGHT*" -delete

Doing this, I managed to reduce my build size from 213 MB to 172 MB.

core-vendor-hardening can clean up test files and any other directories you want.

The only downside is that you have to make an entry per module in composer.json.

"extra": {
    "drupal-core-vendor-hardening": {
        "drupal/core": ["tests","profiles/demo_umami"],
        "drupal/json_field": ["tests"]
    },
}

The above example also shows how to delete the umami profile-- you need to insert the directory path. So, if you want to delete tests from all modules of core, you are looking at a very extensive list.

Note: To actually delete the files after modifying composer.json, you can delete the relevant directory and then run composer.install. If you change composer.json and then run composer update, the files will remain.