In this post I’ll discuss about writing unit tests using Pex and Moles. Pex and Moles are Visual Studio 2010 Power Tools that help Unit Testing .NET applications. Pex automatically generates test suites with high code coverage. Right from the Visual Studio code editor, Pex finds interesting input-output values of your methods, which you can save as a small test suite with high code coverage.
Moles allows to replace any .NET method with a delegate. Moles supports unit testing by providing isolation by way of detours and stubs i.e. Generate a Mole type from the original type and redefine its behavior using delegates. Pex and Moles can be downloaded from http://research.microsoft.com/en-us/projects/pex/.I’ll explain the steps to generate unit tests for a project which calls a WCF service. Pex will be used to generate unit tests. Moles will be generated to isolate the external dependency(WCF proxy) and behavior will be redefined using delegates. The projects inside the sample solution are DemoService: This project is a WCF Service.
DemoLibrary: This project is a Class library and service reference to DemoService has been added. Unit tests will be generated for this project.
ConsoleApp: This project is a Console application.
DemoLibrary.Tests: This is a Test project and contains unit tests for DemoLibrary.The solution structure is displayed below 
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Moles allows to replace any .NET method with a delegate. Moles supports unit testing by providing isolation by way of detours and stubs i.e. Generate a Mole type from the original type and redefine its behavior using delegates. Pex and Moles can be downloaded from http://research.microsoft.com/en-us/projects/pex/.I’ll explain the steps to generate unit tests for a project which calls a WCF service. Pex will be used to generate unit tests. Moles will be generated to isolate the external dependency(WCF proxy) and behavior will be redefined using delegates. The projects inside the sample solution are DemoService: This project is a WCF Service.
DemoLibrary: This project is a Class library and service reference to DemoService has been added. Unit tests will be generated for this project.
ConsoleApp: This project is a Console application.
DemoLibrary.Tests: This is a Test project and contains unit tests for DemoLibrary.The solution structure is displayed below
QR: