Always run build:gutenberg -- --dev after downloading built asset

[desrosj]

A side effect of the changes from Core-64393 has surfaced that is potentially affecting anyone looking to run WordPress from src/.

Previously, the relevant block editor-related files were subject to version control within the src/ directory. They were always present, and they were updated from the dependencies installed through npm when npm run build:dev was run. Because of this, someone could clone wordpress-develop and immediately run the PHPUnit tests without having to run a build script (the files were already in the right spots).

The copy:block-json Grunt task was also responsible for generating the src/wp-includes/blocks/blocks-json.php file and was run before any grunt copy commands were run. This ensured it was present in src/ before copying all of the files over to build on npm run build.

The side effect of this is that when the PHPUnit test suite is run from src/, there are unexpected failures whenever anyone:

• Runs npm run build and not npm run build:dev
• Does not run any build script at all assuming the files are in place.

This issue surfaced in WordPress/phpunit-test-runner#307 and there are many Hosting Test reporters failing with the same errors currently. This is due to the fact that the phpunit-test-runner always runs npm run build as a part of the setup. I haven't found specific reasoning why. But if I had to guess, it's because npm run build:dev was not necessary previously. So running build ensured both ways of running the test suite would work.

On one hand, the test runner is _doing_it_wrong() because regardless of whether the tests are being run from build or src, npm run build is always the command that's run. But given that the files were removed from version control within src/, I think it makes sense to always run build:gutenberg -- --dev to ensure that the expected source files are present in the src/ directory.

Also worth noting is that #11064 aims to restore the files that were removed from version control along with the associated history. Once this happens, this likely wouldn't be necessary anymore (the files will again always at least exist because they are versioned). But because these files have gone missing unexpectedly, this is what I recommend as a fix until #11064 is merged.

Trac ticket: Core-64393.

Use of AI Tools

AI assistance: Yes
Tool(s): Claude
Model(s): Sonnet 4.6
Used Claude to investigate the root cause, and recommend a possible way to fix the issue. An approach different than the one suggested was ultimately used.

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[desrosj]

Merged in r62052.