test_main_page.py

import pytest
from pages.main_page import MainPage
from pages.login_page import LoginPage
from pages.cart_page import CartPage


@pytest.mark.login_guest
class TestLoginFromMainPage(object):
    link = "http://selenium1py.pythonanywhere.com/ru/catalogue/the-shellcoders-handbook_209/"
    def test_guest_can_go_to_login_page(self, browser):
        page = MainPage(browser, self.link) 
        page.open()
        page.go_to_login_page()
        login_page = LoginPage(browser, browser.current_url)
        login_page.should_be_login_page()

    def test_guest_should_see_login_link(self, browser):
        page = MainPage(browser, self.link)
        page.open()
        page.should_be_login_link()

def test_guest_cant_see_product_in_cart_opened_from_main_page(browser):
    link = "http://selenium1py.pythonanywhere.com/"
    page = MainPage(browser, link)
    page.open()
    page.go_to_cart_page()
    cart_page = CartPage(browser, browser.current_url)
    cart_page.should_see_no_products_in_the_cart()