Duplicate code is one of the most pungent code smells. A rule that is often used is to re-structure code once it is duplicated in three or more places.
Common duplication problems, and corresponding solutions are:
| 1 | <?php // phpcs:ignore WordPress.Files.FileName  | 
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| 16 | class ShutdownHandlerTest extends TestCase { | 
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| 17 | |||
| 18 | /**  | 
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| 19 | * The mock Plugins_Handler instance.  | 
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| 20 | *  | 
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| 21 | * @var Plugins_Handler|\PHPUnit\Framework\MockObject\MockObject  | 
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| 22 | */  | 
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| 23 | private $plugins_handler;  | 
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| 24 | |||
| 25 | /**  | 
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| 26 | * Setup runs before each test.  | 
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| 27 | *  | 
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| 28 | * @before  | 
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| 29 | */  | 
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| 30 | 	public function set_up() { | 
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| 35 | |||
| 36 | /**  | 
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| 37 | * Tests that the shutdown handler caches the active plugins.  | 
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| 38 | */  | 
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| 39 | View Code Duplication | 	public function test_shutdown_caches_active_plugins() { | 
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| 54 | |||
| 55 | /**  | 
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| 56 | * Tests that the shutdown handler does not update the cache if it has not changed.  | 
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| 57 | */  | 
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| 58 | View Code Duplication | 	public function test_shutdown_does_not_save_unchanged_cache() { | 
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| 72 | |||
| 73 | /**  | 
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| 74 | * Tests that shutting down early empties the cache.  | 
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| 75 | */  | 
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| 76 | 	public function test_shutdown_early_empties_cache() { | 
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| 86 | |||
| 87 | /**  | 
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| 88 | * Tests that expected exceptions thrown during shutdown aren't propogated.  | 
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| 89 | */  | 
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| 90 | View Code Duplication | 	public function test_shutdown_handles_exceptions() { | 
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| 105 | }  | 
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| 106 |