Fixing risky tests

Makring tests that have no assertions with the annotation to suppress
phpunits warning around risky tests

closes 1370

Author: JimTools

Tests/Spec/JsonSerializerTest.php

@@ -20,6 +20,9 @@ public function testShouldImplementSerializerInterface()
         $this->assertClassImplements(Serializer::class, JsonSerializer::class);
     }
 
+    /**
+     * @doesNotPerformAssertions
+     */
     public function testCouldBeConstructedWithoutAnyArguments()
     {
         new JsonSerializer();