Add check for __MACOSX folder

[TeBenachi]

macOS automatically inserts the __MACOSX folder when creating a zip. The __MACOSX folder is a hidden directory and is not visible to the users as default. There is a way to delete the folder using the command line, but it can be easily missed as it is not visible.
A required or warning message can help remind the Mac users to delete the hidden folder before submission.

[carolinan]

This is already a check in https://github.com/WordPress/theme-check/blob/master/checks/class-file-check.php#L60.
Is it not working?

[TeBenachi]

Thanks for pointing me to the file!

My last upload went through with the__MACOSX folder in the zip. (version 1.0.0)
https://themes.trac.wordpress.org/ticket/106766

I think it is because __MACOSX is rather a folder than a file.

[kafleg]

Did you check the SVN? https://themes.svn.wordpress.org/mebae/1.0.1/ There is not such file found here.

[TeBenachi]

Yes. I removed the __MACOSX from the version 1.0.0 after the initial upload.

[TeBenachi]

Related issue on Slack.
https://wordpress.slack.com/archives/C02RP4Y3K/p1634255617397600

The author also asked if it is possible to remove the hidden files/folders upon uploading the newer version.

[dd32]

I think it is because __MACOSX is rather a folder than a file.

This is the problem indeed, __MACOSX should be moved to https://github.com/WordPress/theme-check/blob/master/checks/class-directories-check.php - but I don't think that's working either, as shown by https://themes.trac.wordpress.org/ticket/106975 which has a .git and .ideas directory.

[TeBenachi]

PR #414 detects __MACOSX and alerts users but it only works when __MACOSX is in the root level.