Lithium Docs

						protected function _compare($type, $expected, $result = null, $trace = null) {
		$compareTypes = function($expected, $result, $trace) {
			$types = array('expected' => gettype($expected), 'result' => gettype($result));

			if ($types['expected'] !== $types['result']) {
				$expected = trim("({$types['expected']}) " . print_r($expected, true));
				$result = trim("({$types['result']}) " . print_r($result, true));
				return compact('trace', 'expected', 'result');
			}
		};
		if ($types = $compareTypes($expected, $result, $trace)) {
			return $types;
		}
		$data = array();

		if (!is_scalar($expected)) {
			foreach ($expected as $key => $value) {
				$newTrace = "{$trace}[{$key}]";
				$isObject = false;

				if (is_object($expected)) {
					$isObject = true;
					$expected = (array) $expected;
					$result = (array) $result;
				}
				if (!array_key_exists($key, $result)) {
					$trace = (!$key) ? null : $newTrace;
					$expected = (!$key) ? $expected : $value;
					$result = ($key) ? null : $result;
					return compact('trace', 'expected', 'result');
				}
				$check = $result[$key];

				if ($isObject) {
					$newTrace = ($trace) ? "{$trace}->{$key}" : $key;
					$expected = (object) $expected;
					$result = (object) $result;
				}
				if ($type === 'identical') {
					if ($value === $check) {
						if ($types = $compareTypes($value, $check, $trace)) {
							return $types;
						}
						continue;
					}
					if ($check === array()) {
						$trace = $newTrace;
						return compact('trace', 'expected', 'result');
					}
					if (is_string($check)) {
						$trace = $newTrace;
						$expected = $value;
						$result = $check;
						return compact('trace', 'expected', 'result');
					}
				} else {
					if ($value == $check) {
						if ($types = $compareTypes($value, $check, $trace)) {
							return $types;
						}
						continue;
					}
					if (!is_array($value)) {
						$trace = $newTrace;
						return compact('trace', 'expected', 'result');
					}
				}
				$compare = $this->_compare($type, $value, $check, $newTrace);

				if ($compare !== true) {
					$data[] = $compare;
				}
			}
			if (!empty($data)) {
				return $data;
			}
		}
		if (!is_scalar($result)) {
			$data = $this->_compare($type, $result, $expected);

			if (!empty($data)) {
				return array(
					'trace' => $data['trace'],
					'expected' => $data['result'],
					'result' => $data['expected']
				);
			}
		}
		if ((($type === 'identical') ? $expected === $result : $expected == $result)) {
			if ($types = $compareTypes($expected, $result, $trace)) {
				return $types;
			}
			return true;
		}
		return compact('trace', 'expected', 'result');
	}