input: from typing import List
  
  
  def simulate_login_automation(website_url: str, username: str, password: str) -> str:
      """ Simulate a Selenium-based login automation for a given website.
      Returns 'Login successful!' if the credentials are correctly entered and the login process is completed without errors.
      >>> simulate_login_automation('http://www.example.com', 'username', 'password')
      'Login successful!'
      """
  
output:     from selenium import webdriver
      from selenium.webdriver.common.by import By
      from selenium.webdriver.common.keys import Keys
  
      # Initialize the WebDriver (assuming ChromeDriver is in PATH)
      driver = webdriver.Chrome()
      driver.get(website_url)
  
      # Find the username and password fields and enter the credentials
      username_field = driver.find_element(By.NAME, 'username')
      password_field = driver.find_element(By.NAME, 'password')
  
      username_field.send_keys(username)
      password_field.send_keys(password)
  
      # Submit the form
      password_field.send_keys(Keys.RETURN)
  
      # Check if login was successful (this is a simple check, actual implementation may vary)
      if 'dashboard' in driver.current_url:
          driver.quit()
          return 'Login successful!'
      else:
          driver.quit()
          return 'Login failed!'