Web automation using .NET

You can use the System.Windows.Forms.WebBrowser control (MSDN Documentation). For testing, it allows your to do the things that could be done in a browser. It easily executes JavaScript without any additional effort. If something went wrong, you will be able to visually see the state that the site is in.

example:

private void buttonStart_Click(object sender, EventArgs e)
{
    webBrowser1.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(webBrowser1_DocumentCompleted);
    webBrowser1.Navigate("http://www.wikipedia.org/");            
}

void webBrowser1_DocumentCompleted(object sender, WebBrowserDocumentCompletedEventArgs e)
{
    HtmlElement search = webBrowser1.Document.GetElementById("searchInput");
    if(search != null)
    {
        search.SetAttribute("value", "Superman");
        foreach(HtmlElement ele in search.Parent.Children)
        {
            if (ele.TagName.ToLower() == "input" && ele.Name.ToLower() == "go")
            {
                ele.InvokeMember("click");
                break;
            }
        }
    }
}

---

To answer your question: how to check a checkbox

for the HTML:

<input type="checkbox" id="testCheck"></input>

the code:

search = webBrowser1.Document.GetElementById("testCheck");
if (search != null)
    search.SetAttribute("checked", "true");

actually, the specific "how to" depends greatly on what is the actual HTML.

---

For handling your multi-threaded problem:

private delegate void StartTestHandler(string url);
private void StartTest(string url)
{
    if (InvokeRequired)
        Invoke(new StartTestHandler(StartTest), url);
    else
    {
        webBrowser1.DocumentCompleted += new WebBrowserDocumentCompletedEventHandler(webBrowser1_DocumentCompleted);
        webBrowser1.Navigate(url);
    }
}

InvokeRequired, checks whether the current thread is the UI thread (actually, the thread that the form was created in). If it is not, then it will try to run StartTest in the required thread.

You could use Selenium WebDriver.

A quick code sample below:

using OpenQA.Selenium;
using OpenQA.Selenium.Firefox;

// Requires reference to WebDriver.Support.dll
using OpenQA.Selenium.Support.UI;

class GoogleSuggest
{
    static void Main(string[] args)
    {
        // Create a new instance of the Firefox driver.
        // Note that it is wrapped in a using clause so that the browser is closed 
        // and the webdriver is disposed (even in the face of exceptions).

        // Also note that the remainder of the code relies on the interface, 
        // not the implementation.

        // Further note that other drivers (InternetExplorerDriver,
        // ChromeDriver, etc.) will require further configuration 
        // before this example will work. See the wiki pages for the
        // individual drivers at http://code.google.com/p/selenium/wiki
        // for further information.
        using (IWebDriver driver = new FirefoxDriver())
        {
            //Notice navigation is slightly different than the Java version
            //This is because 'get' is a keyword in C#
            driver.Navigate().GoToUrl("http://www.google.com/");

            // Find the text input element by its name
            IWebElement query = driver.FindElement(By.Name("q"));

            // Enter something to search for
            query.SendKeys("Cheese");

            // Now submit the form. WebDriver will find the form for us from the element
            query.Submit();

            // Google's search is rendered dynamically with JavaScript.
            // Wait for the page to load, timeout after 10 seconds
            var wait = new WebDriverWait(driver, TimeSpan.FromSeconds(10));
            wait.Until(d => d.Title.StartsWith("cheese", StringComparison.OrdinalIgnoreCase));

            // Should see: "Cheese - Google Search" (for an English locale)
            Console.WriteLine("Page title is: " + driver.Title);
        }
    }
}

The great thing (among others) about this approach is that you can easily switch the underlying browser implementations, just by specifying a different IWebDriver, like FirefoxDriver, InternetExplorerDriver, ChromeDriver, etc. This also means you can write 1 test and run it on multiple IWebDriver implementations, thus testing how the page works when viewed in Firefox, Chrome, IE, etc. People working in QA sector often use Selenium to write automated web page tests.

If you want to simulate a real browser then WatiN will be a good fit for you. (Selenium is another alternative, but I do not recommend it for you).

If you want to work on the HTTP level, then use WebRequest and related classes.

Check out SimpleBrowser, which is a fairly mature, lightweight browser automation library.

https://github.com/axefrog/SimpleBrowser

From the page:

SimpleBrowser is a lightweight, yet highly capable browser automation engine designed for automation and testing scenarios. It provides an intuitive API that makes it simple to quickly extract specific elements of a page using a variety of matching techniques, and then interact with those elements with methods such as Click(), SubmitForm() and many more. SimpleBrowser does not support JavaScript, but allows for manual manipulation of the user agent, referrer, request headers, form values and other values before submission or navigation.