Moq C# (How it Works for Developers)

In the world of software development, testing is an indispensable process. It ensures that your code works as expected and helps catch bugs before they reach production. One vital aspect of testing is mocking, and when it comes to C# testing, MOQ is a powerful tool in a developer's arsenal. It provides support for lambda expressions. MOQ, short for "Mock Object Framework for .NET," simplifies the process of creating mock objects for unit testing. In this article, we will delve into MOQ in C#

What is MOQ?

MOQ is a mocking framework for .NET applications that allows developers to create mock objects quickly and efficiently. Mock objects are objects that simulate the behavior of real objects in your application, making it easier to isolate and test specific parts of your code. MOQ simplifies the process of creating and working with these mock objects.

Key Features of MOQ

• Fluent Interface: MOQ provides a fluent and expressive API for setting up expectations and verifications. This makes your test code more readable and easier to understand.
• Strong Typing: MOQ leverages the C# language features to provide strong typing and IntelliSense support when defining mocks and expectations. This reduces the chances of runtime errors in your tests.
• Loose Mocking: MOQ supports both strict and loose mocking. Loose mocking allows you to create mock objects that respond to any method calls, while strict mocking enforces that only expected methods are called.
• Verifiable Behavior: MOQ allows you to verify that specific methods on your mock objects were called with the expected arguments and in the correct order.
• Callbacks and Returns: You can define callbacks to execute custom code when a mocked method is called and specify return values for mocked methods.

Getting Started with MOQ

In this tutorial, we'll explore how to use MOQ, a popular mocking framework for C#, to facilitate unit testing. We'll walk through an example where we create and test a simple ATM transaction scenario using MOQ to mock dependencies.

Create a new C#

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);
}

' IHostBank.cs
Public Interface IHostBank
	Function AuthenticateAmount(ByVal accountNumber As String, ByVal amount As Integer) As Boolean
End Interface

' IHSMModule.cs
Public Interface IHSMModule
	Function ValidatePIN(ByVal cardNumber As String, ByVal pin As Integer) As Boolean
End Interface

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;
    }
// non static method
    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;
    }
// non static method
    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 hsmModule As IHSMModule
	Private ReadOnly hostBank As IHostBank

	Public Sub New(ByVal hsmModule As IHSMModule, ByVal hostBank As IHostBank)
		Me.hsmModule = hsmModule
		Me.hostBank = hostBank
	End Sub
' non static method
	Public Function WithdrawAmount(ByVal cardNumber As String, ByVal pin As Integer, ByVal amount As Integer) As Boolean
		If Not hsmModule.ValidatePIN(cardNumber, pin) Then
			Return False
		End If

		If Not hostBank.AuthenticateAmount(cardNumber, amount) Then
			Return False
		End If

		' Withdraw the specified amount and perform other operations
		Return True
	End Function
End Class

Create 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 as 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 will add all the required dependencies in the project.

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

using Moq;
using MOQTestProject;

namespace UnitTest
{
    public class Tests
    {
        ATMCashWithdrawal atmCash;
        [SetUp]
        public void Setup()
        {
            // Arrange
            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);
            var atmCash = new ATMCashWithdrawal(hsmModuleMock.Object, hostBankMock.Object); // Object property
        }

        [Test]
        public void WithdrawAmount_ValidTransaction_ReturnsTrue()
        {
            // Act
            bool result = atmCash.WithdrawAmount("123456781234", 1234, 500);

            // Assert
            Assert.IsTrue(result); // Verify method 
        }

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

using Moq;
using MOQTestProject;

namespace UnitTest
{
    public class Tests
    {
        ATMCashWithdrawal atmCash;
        [SetUp]
        public void Setup()
        {
            // Arrange
            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);
            var atmCash = new ATMCashWithdrawal(hsmModuleMock.Object, hostBankMock.Object); // Object property
        }

        [Test]
        public void WithdrawAmount_ValidTransaction_ReturnsTrue()
        {
            // Act
            bool result = atmCash.WithdrawAmount("123456781234", 1234, 500);

            // Assert
            Assert.IsTrue(result); // Verify method 
        }

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

Imports Moq
Imports MOQTestProject

Namespace UnitTest
	Public Class Tests
		Private atmCash As ATMCashWithdrawal
		<SetUp>
		Public Sub Setup()
			' Arrange
			Dim hsmModuleMock = New Mock(Of IHSMModule)()
			hsmModuleMock.Setup(Function(h) h.ValidatePIN("123456781234", 1234)).Returns(True)

			Dim hostBankMock = New Mock(Of IHostBank)()
			hostBankMock.Setup(Function(h) h.AuthenticateAmount("123456781234", 500)).Returns(True)
			Dim atmCash = New ATMCashWithdrawal(hsmModuleMock.Object, hostBankMock.Object) ' Object property
		End Sub

		<Test>
		Public Sub WithdrawAmount_ValidTransaction_ReturnsTrue()
			' Act
			Dim result As Boolean = atmCash.WithdrawAmount("123456781234", 1234, 500)

			' Assert
			Assert.IsTrue(result) ' Verify method
		End Sub

		' Add more test cases for different scenarios (e.g., invalid PIN, insufficient funds, etc.)
	End Class
End Namespace

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, and maintainability, and testing code easier.

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.

Introducing IronPDF

IronPDF is a powerful C# library that allows developers to work with PDF documents within their applications. It offers a wide range of features, including creating, modifying, and converting PDF files from various sources, such as HTML, images, and existing PDFs. When combined with the concept of mocking objects as discussed in the previous tutorial, IronPDF can be a valuable tool for generating and manipulating PDF documents in your unit tests.

IronPDF’s main feature is its HTML to PDF function, ensuring that layouts and styles are intact. It turns web content into PDFs, making it perfect for reports, invoices, and documentation. This feature supports converting HTML files, URLs, and HTML strings to PDFs.

using IronPdf;

class Program
{
    static void Main(string[] args)
    {
        var renderer = new ChromePdfRenderer();

        // 1. Convert HTML String to PDF
        var htmlContent = "<h1>Hello, IronPDF!</h1><p>This is a PDF from an HTML string.</p>";
        var pdfFromHtmlString = renderer.RenderHtmlAsPdf(htmlContent);
        pdfFromHtmlString.SaveAs("HTMLStringToPDF.pdf");

        // 2. Convert HTML File to PDF
        var htmlFilePath = "path_to_your_html_file.html"; // Specify the path to your HTML file
        var pdfFromHtmlFile = renderer.RenderHtmlFileAsPdf(htmlFilePath);
        pdfFromHtmlFile.SaveAs("HTMLFileToPDF.pdf");

        // 3. Convert URL to PDF
        var url = "http://ironpdf.com"; // Specify the URL
        var pdfFromUrl = renderer.RenderUrlAsPdf(url);
        pdfFromUrl.SaveAs("URLToPDF.pdf");
    }
}

using IronPdf;

class Program
{
    static void Main(string[] args)
    {
        var renderer = new ChromePdfRenderer();

        // 1. Convert HTML String to PDF
        var htmlContent = "<h1>Hello, IronPDF!</h1><p>This is a PDF from an HTML string.</p>";
        var pdfFromHtmlString = renderer.RenderHtmlAsPdf(htmlContent);
        pdfFromHtmlString.SaveAs("HTMLStringToPDF.pdf");

        // 2. Convert HTML File to PDF
        var htmlFilePath = "path_to_your_html_file.html"; // Specify the path to your HTML file
        var pdfFromHtmlFile = renderer.RenderHtmlFileAsPdf(htmlFilePath);
        pdfFromHtmlFile.SaveAs("HTMLFileToPDF.pdf");

        // 3. Convert URL to PDF
        var url = "http://ironpdf.com"; // Specify the URL
        var pdfFromUrl = renderer.RenderUrlAsPdf(url);
        pdfFromUrl.SaveAs("URLToPDF.pdf");
    }
}

Imports IronPdf

Friend Class Program
	Shared Sub Main(ByVal args() As String)
		Dim renderer = New ChromePdfRenderer()

		' 1. Convert HTML String to PDF
		Dim htmlContent = "<h1>Hello, IronPDF!</h1><p>This is a PDF from an HTML string.</p>"
		Dim pdfFromHtmlString = renderer.RenderHtmlAsPdf(htmlContent)
		pdfFromHtmlString.SaveAs("HTMLStringToPDF.pdf")

		' 2. Convert HTML File to PDF
		Dim htmlFilePath = "path_to_your_html_file.html" ' Specify the path to your HTML file
		Dim pdfFromHtmlFile = renderer.RenderHtmlFileAsPdf(htmlFilePath)
		pdfFromHtmlFile.SaveAs("HTMLFileToPDF.pdf")

		' 3. Convert URL to PDF
		Dim url = "http://ironpdf.com" ' Specify the URL
		Dim pdfFromUrl = renderer.RenderUrlAsPdf(url)
		pdfFromUrl.SaveAs("URLToPDF.pdf")
	End Sub
End Class

For example, if you have a project involving PDF generation or processing, you can use IronPDF to create mock PDF documents that mimic real-world scenarios. This can be particularly useful for testing and validating how your code interacts with PDF files. You can generate mock PDFs with specific content, layouts, and properties, and then use them as test fixtures to ensure that your code produces the desired PDF outputs or handles PDF-related operations correctly.

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.SaveAsPdfA("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.SaveAsPdfA("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 Sub GenerateFinancialReport(ByVal reportData As String)
		Dim renderer = New ChromePdfRenderer()
		' Generate the report HTML
		Dim reportHtml As String = GenerateReportHtml(reportData)
		Dim pdfDocument As PdfDocument = renderer.RenderHtmlAsPdf(reportHtml)
		' Save the PDF to a file or memory stream
		pdfDocument.SaveAsPdfA("FinancialReport.pdf")
	End Sub

	Private Function GenerateReportHtml(ByVal reportData As String) As String
		' 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>"
	End Function
End Class

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.

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

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

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

}

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

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

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

}

Friend Class PDFGeneratorTests
	<Test>
	Public Sub GenerateFinancialReport_CreatesCorrectPDF()
		' Arrange
		Dim mock = New PDFGenerator()
		Dim expectedPdf = PdfDocument.FromFile("ExpectedFinancialReport.pdf") ' Load a mock PDF

		' Act
		mock.GenerateFinancialReport("Sample report data")
		Dim actualPdf = PdfDocument.FromFile("FinancialReport.pdf")

		' Assert
		Assert.AreEqual(actualPdf.ExtractAllText(), expectedPdf.ExtractAllText())
	End Sub

End Class

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.

Conclusion

In conclusion, leveraging MOQ, along with IronPDF in our unit testing process, allows us to comprehensively verify the behavior of our software applications. MOQ empowers us to isolate specific code components, control dependencies, and simulate complex scenarios, enabling us to write focused and reliable tests.

Meanwhile, IronPDF enhances our testing capabilities by facilitating the generation and manipulation of PDF documents, ensuring that our PDF-related functionalities are thoroughly examined. By integrating these tools into our testing toolkit, we can confidently develop robust and high-quality software that meets the demands of both functionality and performance. This combination of robust unit testing with MOQ and PDF validation with IronPDF contributes significantly to the overall quality and reliability of our applications.

It's worth noting that IronPDF offers a free trial for testing its features. If you find it suits your needs, you have the option to purchase a commercial license. This allows you to continue using IronPDF's capabilities in your projects with the full advantage and support that come with a licensed version, ensuring the smooth integration of PDF-related functionalities into your applications.