I've been planning on writing a quick overview of the basics of unit testing in Silverlight for a while now. Since Windows Phone 7 is the hot topic now, and there are a few quirks with using the Silverlight Unit Test Framework with it, I figured now would be a good chance to write a blog entry covering both. If you're just looking for the cheat sheet relative to both Silverlight and WP7 unit tests, then skip the first section on setting up the test harness on WP7.

Setting up the Test Harness for WP7
To get started, you'll need the Silverlight Unit Test Framework tweaked for Windows Phone 7 from Jeff Wilcox's blog here. I've attached the binaries to this post as well (SL3_UTF_May.zip).

Once you have the binaries, you'll want to create a new test harness project. Do this by creating a new project in your solution of type 'Windows Phone Application'. In the sample attached to this post I'm calling my test project SampleTestProject.

Next, add references to the two Silverlight Unit Test Framework DLLs*:
Microsoft.Silverlight.Testing.dll
Microsoft.VisualStudio.QualityTools.UnitTesting.Silverlight.dll

* you will get a warning about referencing Silverlight 3 assemblies, click 'yes' when asked if you want to continue

Because of recent changes in WP7, you can no longer set the root visual in the App.xaml.cs like normal. Instead, you'll setup the test page in the Loaded() event of your MainPage.xaml.cs in your test project. The following code hides the SystemTray on the phone (the bar at the top of the screen) which otherwise would cover up the top of test results screen, and hooks up the back button to allow you to return back from drilling into test results.

using Microsoft.Phone.Shell;
using Microsoft.Silverlight.Testing;

void MainPage_Loaded(object sender, RoutedEventArgs e)
{
    SystemTray.IsVisible = false;

    var testPage = UnitTestSystem.CreateTestPage() as IMobileTestPage;
    BackKeyPress += (x, xe) => xe.Cancel = testPage.NavigateBack();
    (Application.Current.RootVisual as PhoneApplicationFrame).Content = testPage;            
}

(click 'read more' to keep reading..)