[wp-trac] [WordPress Trac] #39327: Database connection errors in unit tests on 4.7

[WordPress Trac]

#39327: Database connection errors in unit tests on 4.7
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 Reporter:  rmccue                |       Owner:  pento
     Type:  defect (bug)          |      Status:  assigned
 Priority:  normal                |   Milestone:  4.7.1
Component:  Build/Test Tools      |     Version:  4.7
 Severity:  normal                |  Resolution:
 Keywords:  blame-gary has-patch  |     Focuses:
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Changes (by pento):

 * keywords:  needs-patch blame-gary => blame-gary has-patch
 * owner:   => pento
 * status:  new => assigned
 * milestone:  Future Release => 4.7.1


Comment:

 In Core tests, `phpunit.xml.dist` has `backupGlobals="false"` defined,
 hence why we never see this in Core.

 For plugin tests that don't have this option set to `false`, `$wpdb` was
 always being serialised/unserialised between tests, but
 `WP_UnitTestCase::setUp()` took care of reconnecting. The changes to
 `WP_UnitTestCase::setUpBeforeClass()` in [38398] introduced DB
 interactions before the database was reconnected, however, causing this
 warning to appear during plugin tests, but not Core tests.

 For an immediate plugin fix, the best option is to add
 `backupGlobals="false"` to your `phpunit.xms.dist`.

 @rmccue: Could you also confirm that [attachment:39327.diff] fixes the
 warning for you? If so, you'll need to remove the `blame-gary` tag on this
 one. ;-)

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Ticket URL: <https://core.trac.wordpress.org/ticket/39327#comment:2>
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