Unit testing an application

Microsoft has a proprietary unit testing framework known as MS Test, which is closely integrated with Visual Studio. However, to use a unit testing framework that is compatible with .NET Core, we will use the third-party framework: xUnit.net.

Creating a class library that needs testing with Visual Studio 2017

In Visual Studio 2017, add a new Class Library (.NET Standard) project named Ch05_Calculator, as shown in the following screenshot:

In Visual Studio 2017, in the Solution Explorer window, right-click on the Class1.cs file and choose Rename. Change its name to Calculator. You will be prompted to rename all references. Click Yes.

Modify the code to look like this (note the deliberate bug!):

    namespace Ch05_Calculator 
    { 
      public class Calculator 
      { 
        public double Add(double a, double b) 
        { 
          return a * b; 
        } 
      } 
    } 

Creating a unit test project with Visual Studio 2017

In Visual Studio 2017, add a new...