Moq C# (How it Works for Developers)

Create a New C# Project

Follow the following steps to create a new project:

1. Open Visual Studio, go to "File" > "New" > "Project...".
2. Choose a project template, configure settings, and click "Create."

Suppose you're developing software for an ATM (Automated Teller Machine), and you need to test the authentication and withdrawal functionality. The ATM depends on two interfaces: IHostBank and IHSMModule. We want to test the ATMCashWithdrawal class, which represents the ATM's cash withdrawal functionality.

Create two interfaces, IHostBank and IHSMModule, which represent the dependencies of the ATM system. Define relevant methods such as AuthenticateAmount and ValidatePIN.

// IHostBank.cs
public interface IHostBank
{
    bool AuthenticateAmount(string accountNumber, int amount);
}

// IHSMModule.cs
public interface IHSMModule
{
    bool ValidatePIN(string cardNumber, int pin);
}

// IHostBank.cs
public interface IHostBank
{
    bool AuthenticateAmount(string accountNumber, int amount);
}

// IHSMModule.cs
public interface IHSMModule
{
    bool ValidatePIN(string cardNumber, int pin);
}

Create the ATMCashWithdrawal class, which uses the above-mentioned dependencies to perform ATM operations. In this class, you'll implement a certain method like WithdrawAmount.

// ATMCashWithdrawal.cs
public class ATMCashWithdrawal
{
    private readonly IHSMModule hsmModule;
    private readonly IHostBank hostBank;

    public ATMCashWithdrawal(IHSMModule hsmModule, IHostBank hostBank)
    {
        this.hsmModule = hsmModule;
        this.hostBank = hostBank;
    }

    // Withdraw amount after validating PIN and balance
    public bool WithdrawAmount(string cardNumber, int pin, int amount)
    {
        if (!hsmModule.ValidatePIN(cardNumber, pin))
        {
            return false;
        }

        if (!hostBank.AuthenticateAmount(cardNumber, amount))
        {
            return false;
        }

        // Withdraw the specified amount and perform other operations
        return true;
    }
}

// ATMCashWithdrawal.cs
public class ATMCashWithdrawal
{
    private readonly IHSMModule hsmModule;
    private readonly IHostBank hostBank;

    public ATMCashWithdrawal(IHSMModule hsmModule, IHostBank hostBank)
    {
        this.hsmModule = hsmModule;
        this.hostBank = hostBank;
    }

    // Withdraw amount after validating PIN and balance
    public bool WithdrawAmount(string cardNumber, int pin, int amount)
    {
        if (!hsmModule.ValidatePIN(cardNumber, pin))
        {
            return false;
        }

        if (!hostBank.AuthenticateAmount(cardNumber, amount))
        {
            return false;
        }

        // Withdraw the specified amount and perform other operations
        return true;
    }
}

Create a Unit Test Project

Now, let's create unit tests for the ATMCashWithdrawal class using MOQ to mock the dependencies.

Create a new Unit Test Project in your solution and name it ATMSystem.Tests.

To add an NUnit test project to your Visual Studio solution, follow these steps:

1. Right-click on the Solution: In the Solution Explorer (usually on the right-hand side), right-click on the solution name.
2. Add > New Project: From the context menu, select "Add" and then "New Project...".
3. Create a New Project: In the "Add New Project" dialog, you can search for "NUnit" to find available NUnit templates. Choose the NUnit Test Project as shown below.

4. Configure the Project: Configure the project settings as needed, including the project name and location.
5. Click OK: Click the "Create" or "OK" button to add the NUnit test project to your solution.

Now, you have a separate NUnit test project within your solution where you can write and manage your unit tests. You can also add references to the projects you want to test and start writing your NUnit test cases in this project.

To begin using MOQ in the test project, you'll need to add the MOQ NuGet package to your solution. You can do this using the NuGet Package Manager in Visual Studio or by running the following command in the Package Manager Console:

Install-Package Moq

This command will install the package and add all the required dependencies to the project.

Write unit tests using NUnit and MOQ to mock the dependencies (IHostBank and IHSMModule) of the ATMCashWithdrawal class.

using Moq;
using NUnit.Framework;

namespace ATMSystem.Tests
{
    public class ATMTests
    {
        private ATMCashWithdrawal atmCash;

        [SetUp]
        public void Setup()
        {
            // Arrange - Setup mock objects
            var hsmModuleMock = new Mock<IHSMModule>();
            hsmModuleMock.Setup(h => h.ValidatePIN("123456781234", 1234)).Returns(true);

            var hostBankMock = new Mock<IHostBank>();
            hostBankMock.Setup(h => h.AuthenticateAmount("123456781234", 500)).Returns(true);

            atmCash = new ATMCashWithdrawal(hsmModuleMock.Object, hostBankMock.Object);
        }

        [Test]
        public void WithdrawAmount_ValidTransaction_ReturnsTrue()
        {
            // Act - Execute the method under test
            bool result = atmCash.WithdrawAmount("123456781234", 1234, 500);

            // Assert - Verify the result
            Assert.IsTrue(result);
        }

        // More test cases for different scenarios (e.g., invalid PIN, insufficient funds)
    }
}

using Moq;
using NUnit.Framework;

namespace ATMSystem.Tests
{
    public class ATMTests
    {
        private ATMCashWithdrawal atmCash;

        [SetUp]
        public void Setup()
        {
            // Arrange - Setup mock objects
            var hsmModuleMock = new Mock<IHSMModule>();
            hsmModuleMock.Setup(h => h.ValidatePIN("123456781234", 1234)).Returns(true);

            var hostBankMock = new Mock<IHostBank>();
            hostBankMock.Setup(h => h.AuthenticateAmount("123456781234", 500)).Returns(true);

            atmCash = new ATMCashWithdrawal(hsmModuleMock.Object, hostBankMock.Object);
        }

        [Test]
        public void WithdrawAmount_ValidTransaction_ReturnsTrue()
        {
            // Act - Execute the method under test
            bool result = atmCash.WithdrawAmount("123456781234", 1234, 500);

            // Assert - Verify the result
            Assert.IsTrue(result);
        }

        // More test cases for different scenarios (e.g., invalid PIN, insufficient funds)
    }
}

In this test code, we're using MOQ to create mock objects for IHSMModule and IHostBank and specifying their behavior when called during the test.

In the above code example, we've demonstrated the concept of mocking objects using MOQ in C#. We create mock objects for the IHSMModule and IHostBank interfaces, simulating their behavior during unit testing. This allows us to isolate and thoroughly test the ATMCashWithdrawal class by controlling the responses of these mock objects. Through mocking, we can ensure that our code interacts correctly with these dependencies, making our tests focused, predictable, and effective in identifying issues within the specific unit of code under examination. This practice enhances the overall reliability, maintainability, and test code quality.

Step 3 Running the Tests

1. Build your solution to ensure everything is up-to-date.
2. Open the Test Explorer in Visual Studio (Test > Test Explorer).
3. Click the "Run All" button in the Test Explorer to execute your unit tests.
4. Review the test results. You should see the test you wrote (WithdrawAmount_ValidTransaction_ReturnsTrue) pass.

In this way, we can isolate the code we want to test and ensure it behaves as expected under various scenarios by effectively mocking dependencies. This practice improves the reliability and maintainability of your software, making it easier to identify and fix issues early in the development process.

Create Mock Objects for Generating PDFs

Suppose you're developing an application that generates financial reports, and these reports need to be saved and distributed as PDF documents. In this scenario, you might want to test the PDF generation and ensure that the content and formatting are correct.

First, we need to add IronPDF to our project. Write the following command in the NuGet Package Manager Console to install IronPDF.

Install-Package IronPdf

This command will install and add necessary dependencies to our project.

Here's how IronPDF can be incorporated into the unit testing process:

Generating Mock PDFs

You can use IronPDF to create mock PDF documents with specific content and styling to mimic real financial reports. These mock PDFs can serve as test fixtures for your unit tests, as shown in the following code snippet:

public class PDFGenerator
{
    public void GenerateFinancialReport(string reportData)
    {
        var renderer = new ChromePdfRenderer();

        // Generate the report HTML
        string reportHtml = GenerateReportHtml(reportData);
        PdfDocument pdfDocument = renderer.RenderHtmlAsPdf(reportHtml);

        // Save the PDF to a file or memory stream
        pdfDocument.SaveAs("FinancialReport.pdf");
    }

    private string GenerateReportHtml(string reportData)
    {
        // Generate the report HTML based on the provided data
        // (e.g., using Razor views or any HTML templating mechanism)
        // Return the HTML as a string
        return "<h1>my Report</h1>";
    }
}

public class PDFGenerator
{
    public void GenerateFinancialReport(string reportData)
    {
        var renderer = new ChromePdfRenderer();

        // Generate the report HTML
        string reportHtml = GenerateReportHtml(reportData);
        PdfDocument pdfDocument = renderer.RenderHtmlAsPdf(reportHtml);

        // Save the PDF to a file or memory stream
        pdfDocument.SaveAs("FinancialReport.pdf");
    }

    private string GenerateReportHtml(string reportData)
    {
        // Generate the report HTML based on the provided data
        // (e.g., using Razor views or any HTML templating mechanism)
        // Return the HTML as a string
        return "<h1>my Report</h1>";
    }
}

Unit Testing with Mock PDFs

We will write tests for using IronPDF to generate mock PDFs representing various report scenarios. Then, we will compare the actual PDFs generated by our code with these mock PDFs to ensure that the content, formatting, and structure are as expected.

using IronPdf;
using NUnit.Framework;

internal class PDFGeneratorTests
{
    [Test]
    public void GenerateFinancialReport_CreatesCorrectPDF()
    {
        // Arrange
        var pdfGenerator = new PDFGenerator();
        var expectedPdf = PdfDocument.FromFile("ExpectedFinancialReport.pdf"); // Load a mock PDF

        // Act
        pdfGenerator.GenerateFinancialReport("Sample report data");
        var actualPdf = PdfDocument.FromFile("FinancialReport.pdf");

        // Assert
        Assert.AreEqual(actualPdf.ExtractAllText(), expectedPdf.ExtractAllText());
    }
}

using IronPdf;
using NUnit.Framework;

internal class PDFGeneratorTests
{
    [Test]
    public void GenerateFinancialReport_CreatesCorrectPDF()
    {
        // Arrange
        var pdfGenerator = new PDFGenerator();
        var expectedPdf = PdfDocument.FromFile("ExpectedFinancialReport.pdf"); // Load a mock PDF

        // Act
        pdfGenerator.GenerateFinancialReport("Sample report data");
        var actualPdf = PdfDocument.FromFile("FinancialReport.pdf");

        // Assert
        Assert.AreEqual(actualPdf.ExtractAllText(), expectedPdf.ExtractAllText());
    }
}

In this test code, we generate a mock PDF (expectedPdf) representing the expected output and compare it with the PDF (actualPdf) generated by the PDFGenerator. We have extracted the content of both PDFs to verify if they have the same content.