conftest.py

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


def pytest_addoption(parser):
    parser.addoption('--browser', action='store', default='chrome', help="Choose browser: chrome or firefox")
    parser.addoption('--language', action='store', default='en', help="Choose your language")


@pytest.fixture
def browser(request):
    browser = request.config.getoption("--browser")
    browser_language = request.config.getoption("--language")
    if browser == "chrome":
        options = Options()
        options.add_experimental_option('prefs', {'intl.accept_languages': browser_language})
        browser = webdriver.Chrome(options=options)
    elif browser == "firefox":
        fp = webdriver.FirefoxProfile()
        fp.set_preference("intl.accept_languages", browser_language)
        browser = webdriver.Firefox(firefox_profile=fp)
    else:
        raise pytest.UsageError("--browser_name should be chrome or firefox")
    yield browser
    browser.quit()