conftest.py

import pytest
from selenium import webdriver
from selenium.webdriver.chrome.options import Options

def pytest_addoption(parser):
    parser.addoption(
        '--browser_name',
        action = 'store',
        default = 'chrome',
        help = 'choose browser: chrome or firefox'
    )
    parser.addoption(
        '--language',
        action = 'store',
        default = 'ru',
        help = 'choose language'
    )

@pytest.fixture()
def browser(request):
    browser_name = request.config.getoption('browser_name')
    client_language = request.config.getoption('language')
    if browser_name == 'chrome':
        options = Options()
        options.add_experimental_option(
            'prefs',
            {'intl.accept_languages': client_language}
        )
        print('\nStart Google Chrome')
        browser = webdriver.Chrome(options=options)
    elif browser_name == "firefox":
        firefox_profile = webdriver.FirefoxProfile()
        firefox_profile.set_preference("intl.accept_languages", client_language)
        print("\nstart firefox browser for test..")
        browser = webdriver.Firefox()
    else:
        print("Browser {} still is not implemented".format(browser_name))
        browser = None
    yield browser
    print("\nquit browser...")
    browser.quit()