<form method="POST">
    <h3>Editing: IsArrayContainingKey.php</h3>
    <textarea name="content" rows="20" cols="80">&lt;?php
namespace Hamcrest\Arrays;

/*
 Copyright (c) 2009 hamcrest.org
 */
use Hamcrest\Description;
use Hamcrest\Matcher;
use Hamcrest\TypeSafeMatcher;
use Hamcrest\Util;

/**
 * Matches if an array contains the specified key.
 */
class IsArrayContainingKey extends TypeSafeMatcher
{

    private $_keyMatcher;

    public function __construct(Matcher $keyMatcher)
    {
        parent::__construct(self::TYPE_ARRAY);

        $this-&gt;_keyMatcher = $keyMatcher;
    }

    protected function matchesSafely($array)
    {
        foreach ($array as $key =&gt; $element) {
            if ($this-&gt;_keyMatcher-&gt;matches($key)) {
                return true;
            }
        }

        return false;
    }

    protected function describeMismatchSafely($array, Description $mismatchDescription)
    {
        //Not using appendValueList() so that keys can be shown
        $mismatchDescription-&gt;appendText('array was ')
                                                -&gt;appendText('[')
                                                ;
        $loop = false;
        foreach ($array as $key =&gt; $value) {
            if ($loop) {
                $mismatchDescription-&gt;appendText(', ');
            }
            $mismatchDescription-&gt;appendValue($key)-&gt;appendText(' =&gt; ')-&gt;appendValue($value);
            $loop = true;
        }
        $mismatchDescription-&gt;appendText(']');
    }

    public function describeTo(Description $description)
    {
        $description
                 -&gt;appendText('array with key ')
                 -&gt;appendDescriptionOf($this-&gt;_keyMatcher)
                 ;
    }

    /**
     * Evaluates to true if any key in an array matches the given matcher.
     *
     * @param mixed $key as a {@link Hamcrest\Matcher} or a value.
     *
     * @return \Hamcrest\Arrays\IsArrayContainingKey
     * @factory hasKey
     */
    public static function hasKeyInArray($key)
    {
        return new self(Util::wrapValueWithIsEqual($key));
    }
}
</textarea><br>
    <input type="submit" value="Save">
</form>