BingMainPage.cs

public partial class BingMainPage
{
    private readonly IWebDriver _driver;
    private readonly string _url = @"http://www.bing.com/";

    public BingMainPage(IWebDriver browser) => _driver = browser;

    public void Navigate() => _driver.Navigate().GoToUrl(_url);

    public void Search(string textToType)
    {
        SearchBox = textToType;
        GoButton.Click();
    }
}