I'm using WatiN for some automated tests and what I found was that creating an IE instance for every test was not scalable. The creation and shutdown time of each IE instance was eating me alive:
[TestMethod]
public void Verify_Some_Useful_Thing()
{
using (var browser = new IE())
{
browser.GoTo("/someurl");
// etc..
// some assert() statements
}
}
However, the using statement did prove useful in that I can always ensure that my IE instance would have its dispose() method called which would close the IE window.
Anyway, I created a singleton which maintained a single IE instance which all my tests use across all my test classes:
public class BrowserPool
{
private static readonly Lazy<BrowserPool> _instance = new Lazy<BrowserPool>(() => new BrowserPool());
private IE _browser;
private string _ieHwnd;
private int _threadId;
public IE Browser
{
get
{
var currentThreadId = GetCurrentThreadId();
if (currentThreadId != _threadId)
{
_browser = IE.AttachTo<IE>(Find.By("hwnd", _ieHwnd));
_threadId = currentThreadId;
}
return _browser;
}
set
{
_browser = value;
_ieHwnd = _browser.hWnd.ToString();
_threadId = GetCurrentThreadId();
}
}
/// <summary>
/// private to prevent direct instantiation.
/// </summary>
private BrowserPool()
{
Browser = new IE();
}
/// <summary>
/// Get the current executing thread's id.
/// </summary>
/// <returns>Thread Id.</returns>
private int GetCurrentThreadId()
{
return Thread.CurrentThread.GetHashCode();
}
/// <summary>
/// Accessor for instance
/// </summary>
public static BrowserPool Instance
{
get
{
return _instance;
}
}
}
And the test now:
[TestMethod]
public void Verify_Some_Useful_Thing()
{
var browser = BrowserPool.Instance.Browser;
browser.GoTo("/someurl");
// some assertions
}
This works well and my tests run much faster now that I'm not opening and closing IE every test. However, I have this one problem in that when the tests complete my IE instance will still remain open.
I can't figure out an elegant way to ensure that BrowserPool.Browser has dispose() or close() called on it before the application ends. I even tried using a finalizer in the BrowserPool class but that didn't seem to work because the _browser variable had already been reclaimed when my finalizer is called.
How can I ensure that dispose() is called on my IE instance after the test run?
Use the [AssemblyCleanupAttribute()] to clean resources after your tests found in the assembly are finished.
Btw, never rely on the use of destructors in .NET.
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