5 simple steps to execute unit testing using NUNIT

Introduction and Goal

Unit testing is validation and verification methodology where the developers test the individual units of source code. In this tutorial we will try to understand how we can do unit testing using NUNIT framework. This tutorial we will try to understand the 5 important steps to do unit testing using NUNIT.

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The example which we will test
 
Below is a simple class 'clsInvoiceCalculation' which calculates total cost by taking per product cost and number of products as input.

public class clsInvoiceCalculation
{
public int CalculateCost(int intPerProductCost, int intNumberOfProducts)
{
return intPerProductCost * intNumberOfProducts;
}
}

Let's say we want to execute the below test case on the above class using NUNIT.
 

Per product cost	Number of products	Expected output
10	20	200 ( test case passed)

The 5 basic steps to execute the unit test using NUNIT 

Step 1:- The first step is to download to the NUNIT software from http://nunit.org/index.php?p=download 

Step 2:- Create a new C# class project and add reference to "C:\Program Files\NUnit 2.5.2\bin\net-2.0\framework\nunit.framework.dll". We also need to add reference to the class project which we are testing i.e. the invoice project.


Step 3:- Add reference to the NUNIT and your invoice project in your code.

using NUnit.Framework;
using Invoice;

Step 4 :- We need to create a simple class with 'TestFixture' as attribute. We then to create a method attributed with 'Test' which will have our test.


You can see in the above figure how the 'TestInvoiceCalculation' method creates an object of 'clsInvoiceCalculation' , passes the values and checks if the returned values have the expected results. 'Assert' command is used to check if the expected output and the results return match.


Step 5:- Once we are finished with our test case we need to compile the same to create a DLL. Once the DLL compilation is done go to program files – nunit and click on nunit. Now the nunit user interface will open. Click on file – open project and select your test DLL.

Once you select your DLL you will get a screen as shown below. On the right hand side you can see your test class with test function which has the test case. Check the test function and hit run. Now if the test case passes you will see a full green color or else you will see a red color with details of why the test case fails.  


Screenshot when the test case fails.