[wp-trac] [WordPress Trac] #56514: PHP 8.2: fix magic method use within the test suite

[WordPress Trac]

#56514: PHP 8.2: fix magic method use within the test suite
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 Reporter:  jrf                             |       Owner:  SergeyBiryukov
     Type:  defect (bug)                    |      Status:  accepted
 Priority:  normal                          |   Milestone:  6.1
Component:  General                         |     Version:  trunk
 Severity:  normal                          |  Resolution:
 Keywords:  has-patch php82 has-unit-tests  |     Focuses:
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Comment (by SergeyBiryukov):

 In [changeset:"54095" 54095]:
 {{{
 #!CommitTicketReference repository="" revision="54095"
 Tests: Correct magic methods in `Basic_Object`.

 This is a test fixture (dummy class only used in a test context), which
 incorrectly implements the magic methods.

 With the deprecation of dynamic properties in PHP 8.2, this needs to be
 fixed.

 The new implementation represents a “proper” implementation of the magic
 methods for a class without non-`public` or typed properties.

 Notes:

 * Instead of relying on dynamic properties, the magic methods now store
 properties in a `private` `$arbitrary_props` array and retrieve them from
 there as well.
 * The original `$foo` property, even though declared as `private`, was
 never `private` in practice due to the way the magic methods were
 originally implemented. In effect, it was fully publicly retrievable and
 modifiable without any (type) restrictions. With that in mind, the `foo`
 property has been moved into the `$arbitrary_props` array to keep the
 implementation of the magic methods as clean and straightforward as
 possible. With the adjusted magic methods, access to and modification of
 `$foo` will (on the surface) continue to work in the same way as before,
 while under the hood, it is no longer affected by the dynamic properties
 deprecation.
 * Take note of the use of `array_key_exists()` instead of `isset()` in the
 `__get()` method. This is intentional and allows for `null` values to be
 stored and retrieved.
 *  Also take note of `__set()` method no longer returning. `__set()` is
 supposed to be a `void` method. In practice, the return value would always
 be ignored due to how PHP handles magic methods, so in effect, this change
 will not make any difference and does not constitute a backward
 compatibility break.[[BR]][[BR]]
  > The return value of `__set()` is ignored because of the way PHP
 processes the assignment operator.

 Alternatives considered:

 * Instead of fixing the magic methods, they could have been removed
 instead and the class be made to `extend` `stdClass`. It has been chosen
 not to do so for two reasons:
  1. It’s kind of nice to have at least ''one'' correct implementation of
 magic methods in WP, which can be used as an example to point to as well.
  2. Extending `stdClass` would change the class hierarchy, which ''may''
 or ''may not'' affect the tests using this fixture (depending on what’s
 being done with the class). Extending `stdClass` would also obfuscate
 what’s going on in the class and would require extensive documentation to
 prevent the extension being inadvertently removed at a future point in
 time.
 * Instead of fixing the magic methods, the test fixture could have been
 deprecated and/or removed, with the few tests which use the fixture being
 updated to use `stdClass` for their test fixture instead. It has been
 chosen not to do so as there may well be external (plugin/theme) tests
 relying on this test fixture and evaluating whether that is so would be
 hard, as WP Directory cannot be used, since test code is normally not
 included in the code published on wp.org. Also note, there is still a
 (deprecated) `Basic_Subclass` fixture in the test suite, which extends
 this class.

 These magic methods and the `Basic_Object` test fixture were originally
 introduced in [28480] and [28523]. The fixture was deprecated in [42381]
 and undeprecated again in [45807].

 At this time, the test fixture is used in the
 `WP_Test_REST_Post_Meta_Fields` and the `Tests_REST_API` test classes.

 References:
 * [https://www.php.net/manual/en/language.oop5.overloading.php#object.set
 PHP Manual: Overloading: __set()]
 * [https://wiki.php.net/rfc/deprecate_dynamic_properties PHP RFC:
 Deprecate dynamic properties]
 * [https://github.com/php/php-src/issues/7786 php-src: #7786 PHP 8.2:
 unexpected deprecation for dynamic property set via magic method]

 Follow-up to [28480], [28493], [28523], [42381], [45807].

 Props jrf, costdev.
 See #56514.
 }}}

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Ticket URL: <https://core.trac.wordpress.org/ticket/56514#comment:10>
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