Implementation of xUnit in .NET Core

Introduction

Unit testing is a fundamental practice in software development that helps ensure the reliability and correctness of code. In the .NET Core ecosystem, xUnit is one of the most popular testing frameworks used by developers to create and run unit tests. xUnit is an open-source testing framework that offers a rich set of features, an intuitive API, and strong community support. In this article, we will explore the usage of the xUnit package in .NET Core, providing sample code and outputs to illustrate its capabilities. We will cover the setup, implementation, and execution of unit tests using xUnit, along with best practices for writing effective tests.

Setting Up xUnit in .NET Core

To get started with xUnit in a .NET Core project, follow these steps:

Step 1. Create a New .NET Core Project

Open your terminal or command prompt and run the following command to create a new .NET Core console application:

dotnet new console -n XUnitExample
cd XUnitExample

Step 2. Create a Test Project

Create a new class library project for the unit tests:

dotnet new classlib -n XUnitExample.Tests
cd XUnitExample.Tests

Step 3. Add xUnit Packages

Add the xUnit and xUnit.runner.visualstudiopackages to the test project:

dotnet add package xUnit
dotnet add package xUnit.runner.visualstudio

Step 4. Add Project Reference

Add a reference to the main project in the test project:

dotnet add reference ../XUnitExample/XUnitExample.csproj

Writing Unit Tests with xUnit

With the setup complete, let's write some unit tests using xUnit.

Step 5. Create a Sample Class to Test

In the XUnitExample project, create a new file named Calculator.cs and add the following code to define the Calculator class:

namespace XUnitExample
{
    public class Calculator
    {
        public int Add(int a, int b)
        {
            return a + b;
        }

        public int Subtract(int a, int b)
        {
            return a - b;
        }

        public int Multiply(int a, int b)
        {
            return a * b;
        }

        public double Divide(int a, int b)
        {
            if (b == 0)
                throw new DivideByZeroException("Divider cannot be zero");
            return (double)a / b;
        }
    }
}

Step 6. Create Test Classes

In the XUnitExample.Tests project, create a new file named CalculatorTests.cs and add the following code to define the unit tests:

using System;
using Xunit;
using XUnitExample;

namespace XUnitExample.Tests
{
    public class CalculatorTests
    {
        private readonly Calculator _calculator;

        public CalculatorTests()
        {
            _calculator = new Calculator();
        }

        [Fact]
        public void Add_ShouldReturnCorrectSum()
        {
            // Arrange
            int a = 5;
            int b = 3;

            // Act
            int result = _calculator.Add(a, b);

            // Assert
            Assert.Equal(8, result);
        }

        [Fact]
        public void Subtract_ShouldReturnCorrectDifference()
        {
            // Arrange
            int a = 5;
            int b = 3;

            // Act
            int result = _calculator.Subtract(a, b);

            // Assert
            Assert.Equal(2, result);
        }

        [Fact]
        public void Multiply_ShouldReturnCorrectProduct()
        {
            // Arrange
            int a = 5;
            int b = 3;

            // Act
            int result = _calculator.Multiply(a, b);

            // Assert
            Assert.Equal(15, result);
        }

        [Fact]
        public void Divide_ShouldReturnCorrectQuotient()
        {
            // Arrange
            int a = 10;
            int b = 2;

            // Act
            double result = _calculator.Divide(a, b);

            // Assert
            Assert.Equal(5.0, result, 1);
        }

        [Fact]
        public void Divide_ShouldThrowDivideByZeroException()
        {
            // Arrange
            int a = 10;
            int b = 0;

            // Act & Assert
            Assert.Throws<DivideByZeroException>(() => _calculator.Divide(a, b));
        }
    }
}

Step 7. Run the Tests

In the terminal, navigate to the XUnitExample. Test the directory and run the following command:

dotnet test

Sample Output

The output of the test run should indicate that all tests have passed:

Conclusion

xUnit is a powerful and flexible unit testing framework for .NET Core applications, providing a rich set of features and a simple, intuitive API. In this article, we demonstrated how to set up xUnit in a .NET Core project, write unit tests, and run them. The sample code and outputs illustrated the process of testing a Calculator class with various methods, ensuring its correctness and reliability.