Tour of DevForce Silverlight - Unit Testing

Tour wrap-up: Unit testing - Now that we've gone through the five parts in this series we'll show one final, but important step, adding unit tests.

• Platform: Silverlight
• Language: C#, VB
• Download: Tour of DevForce Silverlight - Unit Testing
  
  

Adherents for a "Test First" methodology make a strong case for the importance of writing unit tests as an integral part of your application development process – and one should be commenced early in the development cycle. Let’s see how to lay the foundation for integrated, ongoing, automated testing and test development.

Unit testing with the Silverlight Unit Test Framework

We’ll use the Silverlight Unit Test Framework to set up a test environment for our Silverlight solution. This framework is installed with the Silverlight Toolkit; recall that that is a different animal from the Silverlight Tools:

• The Silverlight Tools is an add-on for Visual Studio 2010 that provides tooling for Microsoft Silverlight 4 and RIA Services. It includes several features:
  • Support for targeting Silverlight 4 in the Silverlight designer and project system ;
  • RIA Services application templates and libraries;
  • Support for Silverlight 4 elevated trust and out-of-browser applications and other new Silverlight 4 features.
    
    
• The Silverlight Toolkit, which includes the test facilities, is, by contrast, a collection of Silverlight controls, components, and utilities made available outside the normal Silverlight release cycle. It adds new functionality quickly for designers and developers, and provides the community an efficient way to help shape product development by contributing ideas and bug reports. It includes full open source code, unit tests, samples and documentation for over 26 new controls covering charting, styling, layout, and user input.

Items in the Silverlight Toolkit are categorized into quality bands to denote their stage of development: Mature/SDK; Stable; Preview; and Experimental. The Silverlight test components are in the Experimental band as of this writing (mid-May, 2010); so expect them to grow, change, and mature with time.

Be sure that you’ve installed the Silverlight Toolkit before proceeding.

Adding automated tests

Let’s get started:

1. Make a copy of the Tour_Pt05Completed solution and name it Tour_Pt99Completed. We’ll work in the latter.
2. Open the Tour_Pt99Completed solution in Visual Studio. From the Visual Studio main menu, select File / Add / New Project.
3. In the Installed Templates panel, find the Silverlight section; within that, find Silverlight Unit Test Application. If it’s not that, you haven't installed the Silverlight Toolkit properly.

Change the name from SilverlightTest1 to SilverlightTest. Click [OK].

Accept all of the default settings on the resulting “New Silverlight Application” dialog:

The template has added a pair of “SilverlightTestTestPage” files to the web project, and made the SilverlightTestTestPage.aspx page the start page for the web project.

It also added a new SilverlightTest project which contains a Tests.cs file with stubs for a test class and method. Since we want to take advantage of Silverlight-specific test features here, we modified the class as follows to inherit from Microsoft.Silverlight.Testing.SilverlightTest.

Since we’ll want to use DevForce facilities in our tests, let’s add the necessary references to the new SilverlightTest project:

• IdeaBlade.Core.SL
• IdeaBlade.EntityModel.SL
• IdeaBlade.Ling.SL
• IdeaBlade.Validation.SL
• SimpleSteps

The SimpleSteps assembly includes a compiled copy of the DevForce-generated business object model, as well as other things we may want to test (such as methods in the view model, MainPageViewModel).

Let’s also add a few using statements:

Creating a test

We’re ready now to create a simple test. Here we’re going to show how to test an asynchronous query. You may not want to perform server queries in your unit tests, but instead rely upon local cache for your test data needs. If you choose to test any server access – login, query, or save - then you’ll need to write an asynchronous test. We show you how here. Modify TestMethod1 to make it appear as follows:

Note several things about this test method:

1. The Asynchronous attribute. This tells the unit test framework that the test contains asynchronously-executed code.
2. The call to base.TestComplete() in the handler. This tells the unit test framework that an asynchronous test is complete.
3. The Tag attribute. This is optional, but allows you to tag your tests to be run in groups.

We’re almost ready to run our test, but first let’s build the solution. We get one error:

DevForce entities are marked with DataContract and DataMember attributes from this assembly, so let’s add the reference now.

Running your tests

Now run the solution. You should see this dialog in your browser window. Ignore it for now (or click the [No, run all tests] button).

You should then see the following page. We’ve expanded the tree control at the left to show the detail on the RetrieveFrenchCustomers test (which passed).

Let’s make the test fail to see what that looks like. Close the browser window to shut down the test application. Find the statement that defines the query and change the match string from “France” to “XXXFrance”:

Re-run the app, again ignoring the “Tag Expressions” dialog. The app now breaks at the Assert statement¹:

If you don’t want each test failure to break, you can disable “Just My Code”. Alternately, you can add any expected test failures, such as the AssertFailedException, to the Debug | Exceptions window:

Once you’ve done so, the Silverlight test UI will show all test results.

Learning more

Your learned the basics of setting up your test project, so you now have a foundation you can build upon. Laying in tests from an early stage will encourage you to factor your code so that it is as testable as possible. You’ll never be sorry!

There’s a lot more to learn about testing than we can cover in this Guide. For example, you can add lots of tests and then run only a subset of them using the Tag attribute; mix synchronous and asynchronous tests, test your UI, and much more. Searching the web for "Silverlight Unit Test Framework" or the like will lead you to many resources. One excellent one is the site of the framework’s author, at http://www.jeff.wilcox.name/topics/dev/testing/.

Resetting the solution to run as a standard DevForce Silverlight app

To set your solution up to run as a regular Silverlight application again, all you need do is to re-establish the Default.aspx page as the web project’s Start Page. Right-click that file in the Solution Explorer, and select Set As Start Page:

Prerequisites

The user interface for the application built during this tour uses a DataForm component supplied by the Silverlight 4 Toolkit (different from the Silverlight 4 Tools!). You can download the Toolkit here:

http://silverlight.codeplex.com/

To work with this application, as all DevForce 2010 Silverlight applications, you will need Visual Studio 2010, the Silverlight 4 runtime (SilverlightTools.exe), and DevForce installed.

1. ^  ...unless you’ve changed certain default settings in Visual Studio, such as turning off the “Enable Just My Code (Managed only)” option in the Debugging section