| Conditions | 2 | 
| Paths | 2 | 
| Total Lines | 8 | 
| Lines | 0 | 
| Ratio | 0 % | 
| Tests | 6 | 
| CRAP Score | 2 | 
| Changes | 0 | ||
| 1 | <?php  | 
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| 9 | 2 | public function __construct(\Traversable $iterator, int $flags = 0, callable $callback = self::UNIQUE_CURRENT)  | 
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| 10 |     { | 
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| 11 | 2 | parent::__construct($iterator, $flags, $callback);  | 
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| 12 | 2 |         if (!$this->getInnerIterator() instanceof \RecursiveIterator) { | 
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| 13 | 1 |             throw new \InvalidArgumentException('An instance of RecursiveIterator or IteratorAggregate creating it is required'); | 
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| 14 | }  | 
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| 15 | 1 | $this->flags = $flags;  | 
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| 16 | 1 | }  | 
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| 17 | |||
| 28 | 
Let’s take a look at an example:
In the above example, the authenticate() method works fine as long as you just pass instances of MyUser. However, if you now also want to pass a different implementation of User which does not have a getDisplayName() method, the code will break.
Available Fixes
Change the type-hint for the parameter:
Add an additional type-check:
Add the method to the interface: