import selenium.webdriver
from selenium.webdriver.common.keys import Keys

def login_test():
    driver = selenium.webdriver.Chrome()
    driver.get("http://example.com/login")

    username_field = driver.find_element_by_id("username")
    username_field.send_keys("test_user")

    password_field = driver.find_element_by_id("password")
    password_field.send_keys("test_password")

    login_button = driver.find_element_by_id("loginButton")
    login_button.click()

if __name__ == "__main__":
    login_test()