Unit testing in c#

In this post I am going to explain about uses of unit testing and writing unit test cases in c#.

Many junior/fresher developers will have confusion like who really deal with Unit testing. Unit test cases are written by developers.

What is Unit Testing?

It tests behavior of a function/method by writing another piece of code.

Why unit tests?

·         Normally Software Projects are intended to run for long term at least for a min. of 5 years.

·         During this period, maintaining the application is very crucial.

·         Any Change Request received might impact the other functionality of the application.

·         So, before deploying the change in Production lot of regression testing has to be done. This consumes lot of tester’s time.

Imagine a situation where the Change requests are happening very frequently, the effort required for regression testing will be very high and the possibility of having defects will also be high.

Software Maintenance with Normal approach (Regression Testing):

Regression testing is the process of testing changes to computer programs to make sure that the older programming still works with the new changes.

Software Maintenance with Unit testing:

·         Unit Tests will certainly help in minimizing the regression testing.

·         Every method will be associated with Test Methods. Test Methods will test the purpose of the actual method.

·         Test Methods will check for below scenarios

·         Positive / Success scenario

·         Negative / Failure scenario

·         Exception / Error Handling scenario

·         A normal method might require more than one Test Method depending on the complexity of the Method.

·         Before Code Delivery., Developer has to ensure that all the test methods (in entire solution) are getting passed.

Software maintenance with TDD (Test Driven Development):

TDD is an evolutionary approach to development which combines test-first development where you write a test before you write just enough production code to fulfill that test and then refactor the code to pass the test.

Writing Unit test cases:

We have below frameworks to write unit test cases in C#.

·    MS Test

·      NUnit

We have AAA pattern to write unit test cases:

Arrange all necessary preconditions and inputs.

Act on the object or method under test.

Assert that the expected results have occurred.

Following are the steps to create the unit test project:

Right click on the solution explorer and click on Add and select Unit Test Project

Solution Explorer:

Test Class:

 using System;

using Microsoft.VisualStudio.TestTools.UnitTesting;

using BusinessManager;

namespace UnitTestProject1

{

    [TestClass]

    public class UnitTest1

    {

        [TestMethod]

        public void GetNameTest()

        {

            //Arrange

            Employee objEmployee = new Employee();

            String firstName = "Narasimha";

            String lastName = "Reddy";

            String expected = "Narasimha Reddy";

            String actual;

            //Act

            actual = objEmployee.GetName(firstName, lastName);

            //Assert

            Assert.AreEqual(expected, actual);

        }

    }

}

Employee Class:

using System;

using System.Collections.Generic;

using System.Linq;

using System.Text;

namespace BusinessManager

{

    public class Employee

    {

        public string GetName(string firstName, string lastName)

        {

            return string.Concat(firstName," ", lastName);

        }

    }

}

I hope you it will help you to get idea on unit testing.

Happy Coding......