How to create test objects in tests?

I'm creating unittests to a payment process. There is about 20 unit unittests to write -some positives cases and some negatives.

example:

payment_screen=PaymentScreen()

and there I few conceptions.

First - create a Payer object with giving attributes:

payer=Payer(last_name,country_code)

country_code is important, because system doesn't allow to sending items to other countries

Second

payer=Payer.return_correct_payer()

something like:

class Payer:

 @staticmethod
开发者_如何学Python def return_correct_payer():
 payer=Payer()
 payer.country_code='US'
 payer.last_name='Smith'

and in both options

payment_screen.fill_payer_data(payer)

And an another conception:

in payment_screen just create two methods:

fill_payer_data_with_correct_data()

and

fill_payer_data_with_uncorrect_data()

Which one is the best? Or maybe you have another idea(I'm sure that you have)

EDIT

Thanks for your replies, but it's not what I need. I just don't want create object Pax in every test case with giving attributes.

I have 20 test cases so now I must write 20 times :

payer=Payer('Smith','US')

I don't want duplicate my code

Maybe what you are looking for is some kind of mocking framework. Then when you test PaymentScreen, you can mock out Payer. For more about mocking frameworks for python look here: What is your favorite Python mocking library?.

Hey.
Probably answer with mocks is what you need in the first place, but I want to show how I create objects in my tests. So if I need a object with given parameters I use BuilderPattern (actually modified BuilderPattern from GOF), which looks like this:

class User  {
    private string firstName;
    private string lastName;

    public User(){};

    //now the essence
    public User withFirstName(strFirstName) {
        this.firstName = strFirstName;
        return this;
    }

    public User withLastName(strLastName) {
        this.lastName = strLastName;
        return this;
    }


    //some other stuff
}  

Then I initiate object with:

User testUser1 = new User()
                           .withFirstName("John")
                           .withLastName("Doe");

and then I do with it, what I need.

P.S. Sorry for code not being python syntax... but you should get it