[wp-trac] [WordPress Trac] #29185: get_terms with parent set incorrectly hides non-empty terms

[WordPress Trac]

#29185: get_terms with parent set incorrectly hides non-empty terms
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 Reporter:  smerriman         |       Owner:
     Type:  defect (bug)      |      Status:  new
 Priority:  normal            |   Milestone:  Awaiting Review
Component:  Taxonomy          |     Version:  3.9.1
 Severity:  normal            |  Resolution:
 Keywords:  needs-unit-tests  |     Focuses:
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Comment (by landakram):

 I wrote some additional unit tests that describe the interplay between
 `child_of`, `parent`, and `hierarchical`. I used this hierarchy for the
 tests:

 * One
     * Two
         * Three (1)
         * Four
     * Five
         * Six (1)
     * Seven


 Here's what I found:

 1. When `hierarchical == true` and `child_of` is set, both children
 ''and'' non-empty descendants are returned. In other words, in the
 hierarchy described, Two, Three, Five, and Six are returned.
 2. When `hierarchical == false` and `child_of` is set, only direct
 children are returned. In the above hierarchy, the returned array is
 ''empty''. I wrote another test which the hierarchy so that a post was
 associated with Seven, and the returned array contained only Seven.
 3. When both `child_of` and `parent` are set, `parent` takes precedent
 over `child_of`.

 4. When `hierarchical == true` and `parent` is set, the returned array is
 empty. '''This is the bug''' — it should return Two and Five.
 5. When `hierarchical == false` and `parent` is set, the returned array is
 empty.
 6. When `hierarchical == true` and both `child_of` and `parent` are set,
 the returned array is empty. '''This is the bug''' — to be consistent with
 the behavior of #3, it should return Two and Five.
 7. When `hierarchical == false` and both `child_of` and `parent` are set,
 the returned array is empty.

 The attached patch includes the unit tests and the fix that boonebgorges
 and I came up with. When patched, #4 and #5 are fixed
 (`test_hierarchical_parent_get_terms` and
 `test_hierarchical_parent_child_of_get_terms` respectively).

 Now, I can't say whether the existing behaviors make 'sense', but the
 proposed patch leaves those behaviors intact while fixing this bug :)

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Ticket URL: <https://core.trac.wordpress.org/ticket/29185#comment:4>
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