Jason De Oliveira

The last blog post in the series introduced some of the new features within Visual Studio 2012, applicable to Test Driven Development (TDD). This blog post is going to show you how to practically use all of those new features and apply them to Test Driven Development. You are going to see a full cycle of TDD using Visual Studio 2012, during the implementation of a simple calculator example!

Phase 1: Write a unit test for a new functionality  

Respecting the Test Driven Development approach, you have to create your unit tests before starting with any implementations. In our example we have to write some unit tests for the methods “Addition” and “Multiplication”. But first of all, we have to add a project of type “Unit Test Project” to our solution (if you do not already have one).

You may now add the necessary unit tests.Here is an example of the unit tests you could add based on the unit test framework NUnit:

Please note that the “Calculator” class and its methods “Addition” and “Multiplication” do not exist at this stage yet.

Visual Studio 2012 provides the possibility to generate the missing code in an automatic way. For that you just have to right-click on the “new Calculator” definition in the unit test project and choose to generate the class via the “Generate/New Type“ option in the menu.

A wizard opens and you are now able to configure multiple options such as the type (classe, struct, interface, enum), the access (public, internal), the destination project and the file name for the generation of the missing class.

The next step, after having auto-generated the “Calculator” class, consists of auto-generating the missing methods within this class. This can be achieved in almost the same way as it was done for the missing class. You do a right-click on the method calls "calculator.Addition(…)” and “calculator.Multiplication(…)” in the unit test project and you generate them via the “Generate/Method Stub” option in the menu.

Here is the auto-generated source code of those two methods:

In the last step of this phase you have to open the “Test Explorer” window where you may now execute all your unit tests. This can be done by clicking on the “RunAll” button or by using the already explained “Post Build Test Runs” option (see the previous blog post in the series).

As expected your unit tests will fail, since the corresponding source code has not been implemented yet. We will see how to do that in the next phase.

Phase 2: Implement the minimum code necessary to pass the test

Now in this phase, the only thing that needs to be done, is to implement the expected functionalities. The idea is to develop the minimum code necessary, which responds to the functional requirements. Everything that concerns optimization and amelioration must not be addressed since it will be treated later in the next phase (refactoring).

Following the implementation you may now restart your unit tests by clicking on the “RunAll” button or by using the already explained “Post Build Test Runs” option (see the previous blog post in the series). Your should see that you unit tests have been terminated successfully. If this is not the case you have to review your code and iterate until all of your unit tests pass successfully.

At this stage the source code corresponds exactly to the functional needs and it provides the expected behavior. The final project structure includes a unit test project as well as an application implementation project.

But the source code might not be optimized. Its quality might not adhere to your quality standards, so it has to be ameliorate. The refactoring can be done without any problems since the unit test assure that there are no regressions. Moreover, regressions can be detected very quickly and thus can be handled as soon as possible. This is going to be explained in the next phase.

Phase 3: Refactor and optimize the source code

The process of improving your source code after the initial implementation phase (Phase 2)  is called “Refactoring”. The source code structure is modified internally without any modifications to the external behavior (very important!!). A source code that just “works” is now transformed into a source code that works in an optimal way. Most of the time, the resulting source code is executing with better performance, using less memory and/or with a better software design.

The refactoring consists of the following steps (non-exhaustive list):

• Detect and eliminate all code duplication
• Limit complexity and the number of classes
• Simplify and optimize method algorithms
• Relocate, rename and harmonize methods
• Improve code readability
• Remove not used code (also called “dead code”)
• Add comments to complex code sections

In our simple example there is nothing to be refactored, since there are neither enough methods nor enough classes. But this last step has to be done in bigger developments at the end of each cycle. Afterwards, a new development cycle starts with  new functionalities from Phase1 on.

The last blog post in the series introduced Test Driven Development (TDD). This blog post is going to talk about some of the new features in Visual Studio 2012, that allow you to successfully apply the TDD approach in your daily work.

Visual Studio 2012 external test framework support

The previous version Visual Studio 2010 already provides the possibility of using external test frameworks. But unfortunately with multiple limitations such as:

• Dependency on third party applications for being able to execute unit tests. For example Gallio needs Icarus Runner if you want to run your unit tests.
• Code coverage analysis does not work natively, only by using third party products (such as NCover for example).
• Execution of unit tests is specific to certain plugins : for example there is a difference if you run your MSTest unit tests from within Visual Studio 2008 or by using Resharper, which may result in problems when trying to apply continuous integration processes.

As you can see, you have to multiply plugins and tools, that might not always be compatible with each other, when using Visual Studio 2010 with external test frameworks. Really not an optimal situation, when you want to benefit from specialized external test frameworks and their advanced functionalities !

One of the major updates of Visual Studio 2012 is the support of several external unit test frameworks for multiple languages without any of the limitations mentioned above.

Here are some of the unit test frameworks that you can now use easily:

For .NET :

• NUnit (http://nunit.org)
• xUnit.net (http://xunit.codeplex.com)
• MBUnit (https://github.com/Gallio/Gallio-VS2011-Integration)

For Javascript/HTML :

• QUnit & Jasmine (http://chutzpah.codeplex.com)

For C++ :

• MSTest Native (http://aka.ms/mstest-native-vs11)

How to use NUnit as external test unit framework 

Lets see how to use NUnit as external test unit framework. First you have to install NUnit (currently as Prerelease) via NuGet.

Then you have to install the test adapter plugin for NUnit (currently as Beta) via the Extension Manager, which you can now find under “Tools/Extensions and Updates…”. Note that all test adapters are free of charge and that the functionality to search and download those adapters is fully integrated in Visual Studio 2012.

After installing the NUnit test adapter plugin, you are able to use all Visual Studio 2012 unit test functionalities together with NUnit. You may for example execute your NUnit unit tests directly from within the Visual Studio 2012 IDE, display the test results in the standard view “Test Explorer” and run a code coverage analysis on your code.

Support for C++ in native MSTest

Another big feature of Visual Studio 2012 is that it now supports native MSTest unit tests for C++ applications. Good news for C++ developers, who may now also apply Test Driven Development using native MSTest as unit test framework.

Following is an example implementation of a unit test in Visual C++ using the native MSTest unit test framework:

Support for async and await in VS 2012 and its unit test framework

Windows 8 and .NET 4.5 introduce a major feature that will have a high impact on software development as we know it: Asynchronous Programming. Visual Studio 2012 and its unit test framework support this new approach perfectly. The async and await keywords, available in .NET 4.5, may now be used for creating unit tests of asynchronous methods.

Lets say that you want to create a unit test for the following asynchronous example method:

The corresponding NUnit test method could be:

In my next blog post I am going to further show you other new features of Visual Studio 2012, which will make your life easier when trying to apply Test Driven Development.