Update the block theme folders to templates and parts

[youknowriad]

See #36548

This PR updates the block themes to use templates and parts instead of block-templates and block-template-parts.
It also keeps backward compatibility, that said a theme can not have "templates" and "block-template-parts" or "block-templates" and "parts". I also updated all the documentation we have.

Notes

The issue also mentions the future of patterns and styles, I think these are not requirements for 5.9

Testing instructions

• Make sure themes with "block-templates" and "block-template-parts" folders work properly.
• Make sure themes with "templates" and "parts" folders work properly.

[carolinan]

Theme Check also needs to be updated, otherwise themes will not be able to be uploaded to WordPress.org
https://github.com/WordPress/theme-check/blob/master/checks/class-fse-required-files-check.php

[youknowriad]

@ockham Do you think you can help with the php unit failures here? I'm not sure I understand the results I'm having and the previous assertions.

[Mamaduka]

Why not accept theme_dir directly and remove calculation logic?

[youknowriad]

From an API point of view, I felt that accepting a them stylesheet (or id) is a bit better.

[Mamaduka]

No strong preference. I was just curious :)

[ockham]

@ockham Do you think you can help with the php unit failures here? I'm not sure I understand the results I'm having and the previous assertions.

@youknowriad I'll have a look!

[ockham]

All of the *_block_template_takes_precedence_over_* tests are failing, which means that the template resolution algorithm thinks that the PHP templates always take precedence -- probably because it can't locate the block templates. So something in template resolution seems to be a bit off still...

[ockham]

Is it possible that the reason for this issue is that the test (end dev) env is using Core trunk, and thus the original versions of the template resolution algorithm that we already backported (since it finds those functions and doesn't need GB's 5.9 compat layer)?

The reason why I think this might be the case is as follows: If I move the text fixture files back from phpunit/fixtures/themes/test-theme/templates/ to phpunit/fixtures/themes/test-theme/block-templates/, the lines that assert that the template resolution algorithm finds the block template no longer fail. In other words, the template resolution algorithm expects to find the templates in block-templates/ (rather than templates/).

[ockham]

Specifically, I think that GB is picking up Core's versions of _get_block_template_file and _get_block_templates_files, respectively, which are hard-wired to block-templates and block-template-parts.

[youknowriad]

@ockham that makes sense, I guess we need to make the fix in both places at the same time.

[youknowriad]

I think actually that we should remove the unit test from here, now that these functions are just in Gutenberg to support old versions.

[ockham]

I think actually that we should remove the unit test from here, now that these functions are just in Gutenberg to support old versions.

Let's just make sure that we've carried them over to wordpress-develop so we don't lose test coverage for some of these cases 👍

[ockham]

I think actually that we should remove the unit test from here, now that these functions are just in Gutenberg to support old versions.

Let's just make sure that we've carried them over to wordpress-develop so we don't lose test coverage for some of these cases 👍

Looks like we still have to backport them: https://github.com/WordPress/wordpress-develop/blob/d87196b560203345b385bef6bef9666e7147bb46/tests/phpunit/tests/block-template.php

[ockham]

I think actually that we should remove the unit test from here, now that these functions are just in Gutenberg to support old versions.

Let's just make sure that we've carried them over to wordpress-develop so we don't lose test coverage for some of these cases 👍

Looks like we still have to backport them: https://github.com/WordPress/wordpress-develop/blob/d87196b560203345b385bef6bef9666e7147bb46/tests/phpunit/tests/block-template.php

I've started a PR: WordPress/wordpress-develop#1920

[ockham]

I think actually that we should remove the unit test from here, now that these functions are just in Gutenberg to support old versions.

#36855

[youknowriad]

The tests here are passing, so this should be good to land now.