public function testEmailMustBeUnique()
 {
     $organization = Organization::find(1);
     $user = new User();
     $user->firstname = 'Kap';
     $user->lastname = 'Choi';
     $user->password = '******';
     $user->organization()->associate($organization);
     $this->assertFalse($user->save());
     $user->delete();
 }