Create calculator project

⏲️ 10 minutes

In this step you’ll create the application that will be tested, also called System Under Test (SUT). The application will be a simple calculator in a C# class library.

1- Open JetBrains Rider and create a new C# class library by selecting “New Solution” from the startup dialog:

Jet Brains Startup Dialog

2- Select “Class library” and use the below configurations and click Create.

  • Solution & Project name: SpecFlowCalculator
  • Solution directory: *choose a location to save the project - in this example the solution is saved to C:\projects
  • Language: C#
  • Framework: netcoreapp3.1

Create Class Library

3- Rename Class1.cs to Calculator.cs and overwrite the content with the following code :

using System;

namespace SpecFlowCalculator
    public class Calculator
        public int FirstNumber { get; set; }
        public int SecondNumber { get; set; }

        public int Add()
            throw new NotImplementedException();

calculator sut

4- Now build the solution by navigating to “Build ➡ Build Solution”. You should see a “Build Succeeded” message in the output window:

calculator sut

📄 The calculator application is now built. In the next step you’ll learn how to create a SpecFlow project.