Add test case can invoke method on non existent class.

Author: josemalonsom

tests/GeneratorTest.php

@@ -204,4 +204,18 @@ public function testCanConfigureMethodsForDoubleOfNonExistentClass()
 
         $this->assertInstanceOf($className, $mock);
     }
+
+    /**
+     * @covers PHPUnit_Framework_MockObject_Generator::getMock
+     */
+    public function testCanInvokeMethodsOfNonExistentClass()
+    {
+        $className = 'X' . md5(microtime());
+
+        $mock = $this->generator->getMock($className, ['someMethod']);
+
+        $mock->expects($this->once())->method('someMethod');
+
+        $mock->someMethod();
+    }
 }