Adding CakeResponse::vary()

lib/Cake/Network/CakeResponse.php

@@ -854,6 +854,27 @@ class CakeResponse {
 		return null;
 	}
 
+/**
+ * Sets the Vary header for the response, if an array is passed,
+ * values will be imploded into a comma separated string. If no 
+ * parameters are passed, then an array with the current Vary header 
+ * value is returned
+ *
+ * @param string|array $cacheVariances a single Vary string or a array 
+ * containig the list for variances.
+ * @return array
+ **/
+	public function vary($cacheVariances = null) {
+		if ($cacheVariances !== null) {
+			$cacheVariances = (array) $cacheVariances;
+			$this->_headers['Vary'] = implode(', ', $cacheVariances);
+		}
+		if (isset($this->_headers['Vary'])) {
+			return explode(', ', $this->_headers['Vary']);
+		}
+		return null;
+	}
+
 /**
  * Returns a DateTime object initialized at the $time param and using UTC
  * as timezone

lib/Cake/Test/Case/Network/CakeResponseTest.php

@@ -763,4 +763,25 @@ class CakeResponseTest extends CakeTestCase {
 
 	}
 
+/**
+ * Tests getting/setting the Vary header
+ *
+ * @return void
+ */
+	public function testVary() {
+		$response = $this->getMock('CakeResponse', array('_sendHeader', '_sendContent'));
+		$response->vary('Accept-encoding');
+		$this->assertEquals(array('Accept-encoding'), $response->vary());
+		$response->expects($this->at(1))
+			->method('_sendHeader')->with('Vary', 'Accept-encoding');
+		$response->send();
+
+		$response = $this->getMock('CakeResponse', array('_sendHeader', '_sendContent'));
+		$response->vary(array('Accept-language', 'Accept-encoding'));
+		$response->expects($this->at(1))
+			->method('_sendHeader')->with('Vary', 'Accept-language, Accept-encoding');
+		$response->send();
+		$this->assertEquals(array('Accept-language', 'Accept-encoding'), $response->vary());
+	}
+
 }