Fix a fatal error when CC is active and the user tries to activate Woo

[nylen]

All Submissions:

• Have you followed the ClassicCommerce Contributing guideline?
• Does your code follow the repo standards?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?

Changes proposed in this Pull Request:

Currently when Classic Commerce is active and a user tries to activate WooCommerce, a fatal error occurs because WooCommerce tries to redefine the global function wc() which is already defined by Classic Commerce.

There is existing code in Classic Commerce to try to prevent this situation, but it doesn't work in this case because on the request where a new plugin is activated it runs after other plugins load and even after the init action. Reference:

• https://github.com/ClassicPress/ClassicPress/blob/1.1.2+dev/src/wp-admin/plugins.php#L43
• https://github.com/ClassicPress/ClassicPress/blob/1.1.2+dev/src/wp-admin/includes/plugin.php#L553

The fix in this PR is to intercept any request that represents an attempt to activate WooCommerce while Classic Commerce is still active. I wouldn't say this is beautiful but it is the only way I could find to get it working.

This is a follow up to #165 #173 and other related changes.

How to test the changes in this Pull Request:

1. Deactivate WooCommerce and activate Classic Commerce.
2. Try to activate WooCommerce while Classic Commerce is still active. Test this both using the "Activate" link for WooCommerce and the "Bulk Actions" forms on the plugins page, since these different UI controls use slightly different code paths to activate a plugin.
3. You should see a notice indicating that both plugins cannot be active at once. (Before this PR you would see a fatal error instead.)

Screenshot - before:

Screenshot - after:

Changelog entry

Fix a fatal error when CC is active and the user tries to activate Woo

[nylen]

This part mirrors the logic here:

• https://github.com/ClassicPress/ClassicPress/blob/1.1.2+dev/src/wp-admin/plugins.php#L18
• https://github.com/ClassicPress/ClassicPress/blob/1.1.2+dev/src/wp-admin/includes/class-wp-list-table.php#L457-L468
• https://github.com/ClassicPress/ClassicPress/blob/1.1.2+dev/src/wp-admin/plugins.php#L73-L79

[timbocode]

Looks good to me.

It's not that ugly :)

That's a nice fix!

[nylen]

Yes, the end result is fine, but the internals are definitely not ideal.

I looked for a filter that might work to block a plugin activation but didn't find one. Also, activating a plugin happens fairly late in the load order, but we need to get in before the admin_notices action at least.

Thanks for taking a look!

[timbocode]

Good to merge