public void SetDefault_ClearsOldDefaultAndUpdatesNewDefault()
{
target.AddUpdate("TestUserName", new PaymentMethod { Id = "1", IsDefault = true });
target.AddUpdate("TestUserName", new PaymentMethod { Id = "2"});
target.SetDefault("TestUserName", "2");
Assert.IsFalse(target.GetAll("TestUserName").First(a=>a.Id == "1").IsDefault);
Assert.IsTrue(target.GetAll("TestUserName").First(a => a.Id == "2").IsDefault);
}
}