Added hasQueryParameterWithKey($key) method.

src/Url.php

@@ -381,6 +381,25 @@ public function removeQueryParameterByKey($key)
 		return $this;
 	}
 
+	/**
+	 * @param string $key
+	 * @return bool
+	 */
+	public function hasQueryParameterWithKey($key)
+	{
+		if (!is_string($key)) {
+			$argumentType = (is_object($key)) ? get_class($key) : gettype($key);
+			throw new \InvalidArgumentException('Expected query parameter key as string; got ' . $argumentType);
+		}
+		$queryParameterCount = $this->countQueryParameters();
+		for ($i = 0; $i < $queryParameterCount; $i++) {
+			if ($this->queryParameters[$i]->getKey() === $key) {
+				return true;
+			}
+		}
+		return false;
+	}
+
 	/**
 	 * @return $this
 	 */

test/UrlTest.php

@@ -98,6 +98,13 @@ public function testInvalidArgument15()
 		$url->setFragment(array());
 	}
 
+	public function testInvalidArgument16()
+	{
+		$this->setExpectedException(get_class(new \InvalidArgumentException()));
+		$url = new Url('https://john:secret@mydomain.com:8443/path/to/resource');
+		$url->hasQueryParameterWithKey(array());
+	}
+
 	public function testParser()
 	{
 		$url = new Url('https://john:secret@mydomain.com:8443/path/to/resource');
@@ -108,6 +115,7 @@ public function testParser()
 		$this->assertTrue($url->hasScheme());
 		$this->assertTrue($url->hasHostname());
 		$this->assertTrue($url->hasPath());
+		$this->assertTrue($url->hasQueryParameterWithKey('arg1'));
 
 		$this->assertEquals(2, $url->countQueryParameters());