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  | 
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| 15 | class RenameTagCommandTest extends TestCase  | 
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| 16 | { | 
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| 17 | /**  | 
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| 18 | * @var RenameTagCommand  | 
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| 19 | */  | 
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| 20 | private $command;  | 
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| 21 | /**  | 
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| 22 | * @var CommandTester  | 
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| 23 | */  | 
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| 24 | private $commandTester;  | 
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| 25 | /**  | 
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| 26 | * @var ObjectProphecy  | 
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| 27 | */  | 
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| 28 | private $tagService;  | 
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| 29 | |||
| 30 | public function setUp()  | 
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| 40 | |||
| 41 | /**  | 
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| 42 | * @test  | 
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| 43 | */  | 
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| 44 | View Code Duplication | public function errorIsPrintedIfExceptionIsThrown()  | 
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| 60 | |||
| 61 | /**  | 
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| 62 | * @test  | 
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| 63 | */  | 
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| 64 | View Code Duplication | public function successIsPrintedIfNoErrorOccurs()  | 
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| 80 | }  | 
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| 81 | 
This check marks private properties in classes that are never used. Those properties can be removed.