NUnit Testing and Moq

 

 Initial Steps for Service Layer Testing in ASP.NET Core (NUnit + Moq)

We will set up unit testing for the Service Layer using:

• ✅ NUnit (for testing framework)
• ✅ Moq (for mocking dependencies)
• ✅ FluentAssertions (for better assertions)

---

🔹 Step 1: Install Dependencies

Open the Package Manager Console in Visual Studio and run:

powershellt
Install-Package NUnit
Install-Package Moq
Install-Package FluentAssertions
Install-Package Microsoft.NET.Test.Sdk
Install-Package NUnit3TestAdapter

Alternatively, add dependencies in .csproj:

xml
<ItemGroup>
    <PackageReference Include="NUnit" Version="3.13.3" />
    <PackageReference Include="Moq" Version="4.18.2" />
    <PackageReference Include="FluentAssertions" Version="6.11.0" />
    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.5.0" />
    <PackageReference Include="NUnit3TestAdapter" Version="4.3.1" />
</ItemGroup>

---

🔹 Step 2: Create a Test Project

1️⃣ Right-click the solution → Add → New Project
2️⃣ Select "xUnit Test Project" or "NUnit Test Project"
3️⃣ Name it: DemoJune2024EmsSystem.Tests
4️⃣ Add reference to the main project (DemoJune2024EmsSystem):

• Right-click Test Project → Add Reference → Select Main Project

---

🔹 Step 3: Create a Sample Service to Test

In the main project (DemoJune2024EmsSystem), define:

📌 IEmployeeService.cs

public interface IEmployeeService

{

    List<Employee> GetAllEmployees();

    Employee GetEmployeeById(int id);

    bool AddEmployee(Employee employee);

}

c

📌 EmployeeService.cs

public class EmployeeService : IEmployeeService

{

    private readonly IEmployeeRepository _employeeRepository;

    public EmployeeService(IEmployeeRepository employeeRepository)

    {

        _employeeRepository = employeeRepository;

    }

    public List<Employee> GetAllEmployees()

    {

        return _employeeRepository.GetAllEmployees();

    }

    public Employee GetEmployeeById(int id)

    {

        if (id <= 0)

            throw new ArgumentException("Invalid Employee ID");

        return _employeeRepository.GetEmployeeById(id);

    }

    public bool AddEmployee(Employee employee)

    {

        if (employee == null || string.IsNullOrEmpty(employee.Name))

            return false;

        _employeeRepository.AddEmployee(employee);

        return true;

    }

}

---

🔹 Step 4: Create the Unit Test Class

Inside DemoJune2024EmsSystem.Tests project, create:

📌 EmployeeServiceTests.cs

using DemoJune2024EmsSystem.Models;

using DemoJune2024EmsSystem.Repository;

using DemoJune2024EmsSystem.Services;

using FluentAssertions;

using Moq;

using NUnit.Framework;

using System;

using System.Collections.Generic;

namespace DemoJune2024EmsSystem.Tests

{

    [TestFixture] // Marks the class as a test class

    public class EmployeeServiceTests

    {

        private Mock<IEmployeeRepository> _employeeRepositoryMock;

        private EmployeeService _employeeService;

        [SetUp] // Runs before each test

        public void Setup()

        {

            _employeeRepositoryMock = new Mock<IEmployeeRepository>();

            _employeeService = new EmployeeService(_employeeRepositoryMock.Object);

        }

        [Test]

        public void GetAllEmployees_ShouldReturnListOfEmployees()

        {

            // Arrange

            var employees = new List<Employee>

            {

                new Employee { Id = 1, Name = "John Doe" },

                new Employee { Id = 2, Name = "Jane Doe" }

            };

            _employeeRepositoryMock.Setup(repo => repo.GetAllEmployees()).Returns(employees);

            // Act

            var result = _employeeService.GetAllEmployees();

            // Assert

            result.Should().NotBeNull().And.HaveCount(2);

            result[0].Name.Should().Be("John Doe");

        }

        [Test]

        public void GetEmployeeById_ShouldReturnEmployee_WhenIdIsValid()

        {

            // Arrange

            var employee = new Employee { Id = 1, Name = "John Doe" };

            _employeeRepositoryMock.Setup(repo => repo.GetEmployeeById(1)).Returns(employee);

            // Act

            var result = _employeeService.GetEmployeeById(1);

            // Assert

            result.Should().NotBeNull();

            result.Name.Should().Be("John Doe");

        }

        [Test]

        public void GetEmployeeById_ShouldThrowException_WhenIdIsInvalid()

        {

            // Arrange

            int invalidId = -1;

            // Act

            Action act = () => _employeeService.GetEmployeeById(invalidId);

            // Assert

            act.Should().Throw<ArgumentException>().WithMessage("Invalid Employee ID");

        }

        [Test]

        public void AddEmployee_ShouldReturnTrue_WhenValidEmployeeIsProvided()

        {

            // Arrange

            var employee = new Employee { Id = 1, Name = "John Doe" };

            _employeeRepositoryMock.Setup(repo => repo.AddEmployee(employee));

            // Act

            var result = _employeeService.AddEmployee(employee);

            // Assert

            result.Should().BeTrue();

        }

        [Test]

        public void AddEmployee_ShouldReturnFalse_WhenEmployeeIsNull()

        {

            // Act

            var result = _employeeService.AddEmployee(null);

            // Assert

            result.Should().BeFalse();

        }

        [Test]

        public void AddEmployee_ShouldReturnFalse_WhenNameIsEmpty()

        {

            // Arrange

            var employee = new Employee { Id = 1, Name = "" };

            // Act

            var result = _employeeService.AddEmployee(employee);

            // Assert

            result.Should().BeFalse();

        }

    }

}

---

🔹 Step 5: Run the Tests

1️⃣ Open Test Explorer in Visual Studio (Test → Test Explorer)
2️⃣ Click Run All to execute the tests
3️⃣ The tests should pass ✅

---

🔹 Explanation of Test Cases

Test Case	Expected Behavior
GetAllEmployees_ShouldReturnListOfEmployees	Returns a list of employees from the repository
GetEmployeeById_ShouldReturnEmployee_WhenIdIsValid	Fetches an employee correctly
GetEmployeeById_ShouldThrowException_WhenIdIsInvalid	Throws an exception for invalid IDs
AddEmployee_ShouldReturnTrue_WhenValidEmployeeIsProvided	Successfully adds an employee
AddEmployee_ShouldReturnFalse_WhenEmployeeIsNull	Fails to add a null employee
AddEmployee_ShouldReturnFalse_WhenNameIsEmpty	Fails when employee name is empty

---

🔹 Summary

✔ Service Layer Testing is essential because it verifies business logic.
✔ Moq is used to mock the Repository Layer, so tests run independently.
✔ NUnit and FluentAssertions make tests cleaner and more readable.
✔ These tests are fast and do not require a database connection.