fix behaviour of HTTP/Request get

src/Http/Request.php

@@ -38,9 +38,9 @@ class Request extends SymfonyRequest
      */
     public function has($key)
     {
-        $value = $this->input($key);
+        $value = $this->input($key, null);
 
-        return !empty($value);
+        return !($value === null);
     }
 
     /**

tests/Unit/Http/RequestTest.php

@@ -47,7 +47,8 @@ class RequestTest extends TestCase
         ]);
 
         $this->assertTrue($request->has('foo'));
-        $this->assertFalse($request->has('bar'));
+        $this->assertTrue($request->has('bar'));
+        $this->assertFalse($request->has('baz'));
     }
 
     /**