--- /dev/null
+<?php
+/*
+ * This file is part of PHPUnit.
+ *
+ * (c) Sebastian Bergmann <sebastian@phpunit.de>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+/**
+ * Constraint that asserts that the array it is evaluated for has a given key.
+ *
+ * Uses array_key_exists() to check if the key is found in the input array, if
+ * not found the evaluation fails.
+ *
+ * The array key is passed in the constructor.
+ *
+ * @since Class available since Release 3.0.0
+ */
+class PHPUnit_Framework_Constraint_ArrayHasKey extends PHPUnit_Framework_Constraint
+{
+ /**
+ * @var int|string
+ */
+ protected $key;
+
+ /**
+ * @param int|string $key
+ */
+ public function __construct($key)
+ {
+ parent::__construct();
+ $this->key = $key;
+ }
+
+ /**
+ * Evaluates the constraint for parameter $other. Returns true if the
+ * constraint is met, false otherwise.
+ *
+ * @param mixed $other Value or object to evaluate.
+ *
+ * @return bool
+ */
+ protected function matches($other)
+ {
+ if (is_array($other)) {
+ return array_key_exists($this->key, $other);
+ }
+
+ if ($other instanceof ArrayAccess) {
+ return $other->offsetExists($this->key);
+ }
+
+ return false;
+ }
+
+ /**
+ * Returns a string representation of the constraint.
+ *
+ * @return string
+ */
+ public function toString()
+ {
+ return 'has the key ' . $this->exporter->export($this->key);
+ }
+
+ /**
+ * Returns the description of the failure
+ *
+ * The beginning of failure messages is "Failed asserting that" in most
+ * cases. This method should return the second part of that sentence.
+ *
+ * @param mixed $other Evaluated value or object.
+ *
+ * @return string
+ */
+ protected function failureDescription($other)
+ {
+ return 'an array ' . $this->toString();
+ }
+}