Use the Time utility instead of \DateTime

Doing this allows the mocked time objects to take effect.

src/Controller/Component/CookieComponent.php

@@ -16,14 +16,14 @@
 
 use Cake\Controller\Component;
 use Cake\Controller\ComponentRegistry;
-use Cake\Controller\Controller;
 use Cake\Core\Configure;
 use Cake\Error;
 use Cake\Event\Event;
 use Cake\Network\Request;
 use Cake\Network\Response;
 use Cake\Utility\Hash;
 use Cake\Utility\Security;
+use Cake\Utility\Time;
 
 /**
  * Cookie Component.
@@ -301,7 +301,7 @@ public function delete($key) {
  */
 	protected function _write($name, $value) {
 		$config = $this->configKey($name);
-		$expires = new \DateTime($config['expires']);
+		$expires = new Time($config['expires']);
 
 		$this->_response->cookie(array(
 			'name' => $name,
@@ -325,7 +325,7 @@ protected function _write($name, $value) {
  */
 	protected function _delete($name) {
 		$config = $this->configKey($name);
-		$expires = new \DateTime('now');
+		$expires = new Time('now');
 
 		$this->_response->cookie(array(
 			'name' => $name,

tests/TestCase/Controller/Component/CookieComponentTest.php

@@ -22,6 +22,7 @@
 use Cake\Network\Response;
 use Cake\TestSuite\TestCase;
 use Cake\Utility\Security;
+use Cake\Utility\Time;
 
 /**
  * CookieComponentTest class
@@ -278,7 +279,7 @@ public function testWriteWithFalseyValue() {
 	public function testWriteFarFuture() {
 		$this->Cookie->configKey('Testing', 'expires', '+90 years');
 		$this->Cookie->write('Testing', 'value');
-		$future = new \DateTime('now');
+		$future = new Time('now');
 		$future->modify('+90 years');
 
 		$expected = array(
@@ -310,7 +311,7 @@ public function testWriteHttpOnly() {
 		$expected = array(
 			'name' => 'Testing',
 			'value' => 'value',
-			'expire' => time() + 10,
+			'expire' => (new Time('+10 seconds'))->format('U'),
 			'path' => '/',
 			'domain' => '',
 			'secure' => false,
@@ -361,7 +362,7 @@ public function testDeleteHttpOnly() {
 		$expected = array(
 			'name' => 'Testing',
 			'value' => '',
-			'expire' => time() - 42000,
+			'expire' => (new Time('now'))->format('U') - 42000,
 			'path' => '/',
 			'domain' => '',
 			'secure' => false,
@@ -387,7 +388,8 @@ public function testWriteArrayValues() {
 		);
 		$result = $this->Controller->response->cookie('Testing');
 
-		$this->assertWithinMargin($result['expire'], time() + 10, 1);
+		$time = new Time('now');
+		$this->assertWithinMargin($result['expire'], $time->format('U') + 10, 1);
 		unset($result['expire']);
 		$this->assertEquals($expected, $result);
 	}