public function testConstructor()
 {
     $role_set = new RoleSet([$this->generateRole(), $this->generateRole()]);
     $subject_1 = new Subject(1, $role_set);
     $this->assertEquals(1, $subject_1->id());
     $this->assertEquals($role_set, $subject_1->getRoleSet());
     $subject_2 = new Subject(2);
     $this->assertEquals(0, sizeof($subject_2->getRoleSet()->getRoles()));
     $this->assertEquals(2, $subject_2->id());
 }