Unit Testing with xUnit

Introduction

As a software developer, it is crucial to ensure the quality and reliability of code, and unit testing is one of the best practices to achieve this. With xUnit, a popular unit testing framework in the .NET ecosystem, developers can easily write comprehensive unit tests that validate that each unit of the software code performs as expected. By embracing the power of xUnit and incorporating unit testing into the development workflow, developers can save time and resources and significantly improve the overall software quality. So, let's start writing effective unit tests for our .NET projects today!

Understanding Unit Testing

Unit testing is a software testing method where individual components or functions of a software application are tested in isolation to validate that each unit of the software performs as designed. The purpose is to validate that each unit of the software code performs as expected. A unit is the smallest testable part of any software. In object-oriented programming, a unit could be a method or a class.

The primary goals of unit testing include:

• Isolating Each Part: Unit tests should be isolated, meaning they should test a specific piece of functionality in the application without relying on other parts of the system.
• Automation: Unit tests should be automated and repeatable, allowing developers to run them frequently to catch regressions as soon as they are introduced.
• Quick Execution: Unit tests should be fast, enabling developers to get quick feedback about the code's correctness.

Introduction to xUnit

xUnit is an open-source unit testing framework for .NET languages. It is a part of the xUnit testing family, which also includes frameworks for other programming languages like Java and PHP. xUnit follows the xUnit architecture, which is based on four main principles:

• Setup: Prepare the necessary preconditions for the test.
• Act: Execute the unit of code to be tested.
• Assert: Verify the unit of code behaves as expected.
• Teardown: Clean up any resources allocated during the test.

xUnit provides a simple and elegant way to write unit tests for your .NET applications.

Implementing Unit Tests with xUnit in .NET
 

Step 1. Creating a new Console App in Visual Studio

Now create a Class name Calculator

public class Calculator
{
    public double Add(double number1, double number2)
    {
        return (number1 + number2);
    }

    public double Subtract(double number1, double number2)
    {
        return (number1 - number2);
    }
}

Now you can build this project.

Step 2. Create a new xUnit Project

After creating the new xUnit project, we need to add a reference to our first project. This can be done by right-clicking on the References folder in the xUnit project and selecting "Add Reference". Then select the project you want to reference and click "OK." This will allow us to use the classes and methods defined in our first project in our xUnit tests.

Now writing the test

Calculator cal = new Calculator();

[Fact]
public void Test_AddTwoNumber()
{
    // Arrange  
    var num1 = 3.5;
    var num2 = 5.5;
    var expectedValue = 9;            
    
    // Act  
    var sum = cal.Add(num1, num2);
    
    //Assert  
    Assert.Equal(expectedValue, sum, 1);
}

[Fact]
public void Test_SubtractTwoNumber()
{
    // Arrange  
    var num1 = 6;
    var num2 = 2;
    var expectedValue = 4;
    
    // Act  
    var sum = cal.Subtract(num1, num2);
    
    //Assert  
    Assert.Equal(expectedValue, sum, 1);
}

Step 3. Running test

To run the test, you need to right-click on the xUnit Test project and select "Run Test". This will execute all the unit tests written in the project and display the test results. Make sure to do this after writing the unit tests to ensure that they are working correctly and catching any regressions as soon as they are introduced.

After running the test, you can see the results displayed on the screen. This is a critical step in the unit testing process as it helps to identify any issues or bugs in the code. By running the test frequently, developers can catch any regressions as soon as they are introduced, allowing them to fix the issues quickly and efficiently. It is also important to note that unit tests should be automated and repeatable, which means that they can be run quickly and easily, providing developers with quick feedback about the code's correctness. With xUnit, developers can easily write comprehensive unit tests for their .NET projects, ensuring the reliability and maintainability of their codebase.

Conclusion

Unit testing is a vital practice in modern software development, and xUnit simplifies the process for .NET developers. By writing comprehensive unit tests using xUnit, developers can ensure the reliability and maintainability of their codebase, leading to more robust and bug-free applications. Incorporating unit testing into the development workflow not only saves time and resources but also contributes significantly to the overall software quality. So, embrace the power of xUnit and start writing effective unit tests for your .NET projects today!