wp_update_term() shouldn't allow a term to be assigned to a missing parent

[danielbachhuber]

Easiest to mimic the new behavior established in #19205

Discovered in ​https://github.com/wp-cli/wp-cli/pull/1384

[jesin]

Patch and unit test

[jesin]

Patch 29614.diff​ includes a unit test that uses wp_update_term(). Does $this->factory->category->create() have a replacement for update?

[nacin]

The unit test factory is for initializing objects that may be needed during the test. An actual update should use wp_update_term().

The test should probably also assert first that changing its parent to a term that exists also works.

Also, we should probably assert that the category's parent changed to 0 after deletion, and that we're then trying to change it back.

[jesin]

Includes 29614.diff​ and adds more assertions

[jesin]

Patch 29614.2.diff​ includes assertions for change to existing parent and deletion of a parent.

Without the patch the third assertion fails.

The term cache had to be cleared with clean_term_cache(). Do we have a method of getting terms without caching them?

[wonderboymusic]

The only terms that get cleaned are those that are attached to posts <---- that is a bug. You should never have to call clean_term_cache() directly in app code or unit tests.

We need to figure out how to clean terms that are not attached to posts on update.

[boonebgorges]

The only terms that get cleaned are those that are attached to posts <---- that is a bug.

Yes, but it's a red herring. The issue here is that wp_update_term() should fail when the parent doesn't exist, not necessarily that it should fail when the parent is *deleted*. So the proposed unit test is testing too many things. I'll open a separate ticket for it.

[boonebgorges]

In 29867:

Return an error when adding a term to a non-existent parent.

Parallels the logic of wp_insert_term(), introduced in [29196].

Props jesin.
Fixes #29614.

[boonebgorges]

Replying to wonderboymusic:

The only terms that get cleaned are those that are attached to posts <---- that is a bug. You should never have to call clean_term_cache() directly in app code or unit tests.

We need to figure out how to clean terms that are not attached to posts on update.

Following up: I don't see any evidence that being attached to posts has anything to with it. In this case, it has to do with clearing the cache for child terms when the parent is deleted. #29911.