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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| 8 | trait JsonApiAssertions  | 
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| 9 | { | 
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| 10 | /**  | 
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| 11 | * Assert that all given keys are set in an associative array. Nested  | 
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| 12 | * members may be specified using dot notation.  | 
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| 13 | *  | 
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| 14 | * @param array $keys  | 
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| 15 | * @param array $array  | 
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| 16 | *  | 
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| 17 | * @throws PHPUnit_Framework_AssertionFailedError  | 
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| 18 | */  | 
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| 19 | public function assertArrayHasAll(array $keys, array $array)  | 
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| 27 | |||
| 28 | /**  | 
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| 29 | * Assert that an array contains a valid JSON API resource identifier.  | 
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| 30 | *  | 
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| 31 | * @param array $array  | 
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| 32 | *  | 
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| 33 | * @throws PHPUnit_Framework_AssertionFailedError  | 
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| 34 | */  | 
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| 35 | public function assertJsonApiResourceIdentifier(array $array)  | 
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| 39 | |||
| 40 | /**  | 
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| 41 | * Assert that an array contains a valid JSON API resource object.  | 
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| 42 | *  | 
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| 43 | * @param array $array  | 
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| 44 | *  | 
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| 45 | * @throws PHPUnit_Framework_AssertionFailedError  | 
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| 46 | */  | 
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| 47 | public function assertJsonApiResourceObject(array $array)  | 
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| 51 | |||
| 52 | /**  | 
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| 53 | * Assert that an array contains a valid JSON API resource identifier  | 
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| 54 | * object collection.  | 
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| 55 | *  | 
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| 56 | * @param array $array  | 
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| 57 | * @param int $count  | 
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| 58 | *  | 
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| 59 | * @throws PHPUnit_Framework_AssertionFailedError  | 
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| 60 | */  | 
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| 61 | View Code Duplication | public function assertJsonApiIdentifierCollection(array $array, $count = null)  | 
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| 71 | |||
| 72 | /**  | 
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| 73 | * Assert that an array contains a valid JSON API resource object collection.  | 
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| 74 | *  | 
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| 75 | * @param array $array  | 
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| 76 | * @param int $count  | 
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| 77 | *  | 
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| 78 | * @throws PHPUnit_Framework_AssertionFailedError  | 
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| 79 | */  | 
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| 80 | View Code Duplication | public function assertJsonApiObjectCollection(array $array, $count = null)  | 
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| 90 | }  | 
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| 91 | 
This check looks for methods that are used by a trait but not required by it.
To illustrate, let’s look at the following code example
The trait
Idableprovides a methodequalsIdthat in turn relies on the methodgetId(). If this method does not exist on a class mixing in this trait, the method will fail.Adding the
getId()as an abstract method to the trait will make sure it is available.