While writing this chapter, I used the following version of Visual Studio:

• Visual Studio Enterprise 2022 version 17.12.0
• Preview 1.0

The code files for this chapter can be found at https://github.com/PacktPublishing/Mastering-Visual-Studio-2022/tree/main/ch01

Before delving into the usage of unit testing and the TDD approach through Visual Studio, let’s begin with a refresher on what they are and why it’s valuable to consider them in your project.

Unit testing is a focused software testing method that targets individual units or components within a software system. The primary aim of unit testing is to ensure that each software unit functions as intended, meeting specified requirements. Typically conducted by developers, unit testing takes place early in the development stage, preceding the integration and testing of the entire system.

Automated unit tests are executed whenever code undergoes modification, ensuring that new changes do not disrupt existing functionality. These tests are meticulously crafted to validate the smallest conceivable unit of code, such as a function or method, in isolation from the broader system. This approach empowers developers to swiftly identify and address...

In this section, we will first create a unit test project within Visual Studio. Once that is done, we’ll go through an overview of the Test Explorer view and its main options. The Test Explorer view serves as a central hub for all testing activities within the IDE, offering a comprehensive overview of our test suite’s status and performance. It allows us to easily navigate through test results, identify failures, and access detailed information about each test case.

Creating a unit test project

Visual Studio and .NET support three testing frameworks:

• MSTest: This is the default testing framework provided by Microsoft for .NET applications. It’s fully integrated into Visual Studio and offers features for writing and running tests within the IDE.
• NUnit: This is a popular open-source testing framework for .NET applications. It provides a flexible and extensible platform for writing and executing tests...

In this section, our goal is to explore how to use IntelliTest for creating tests. For that, we will first learn how to enable the IntelliTest functionality. Next, we will learn how to execute it and generate tests with it. At the end of the section, we will learn how to organize our generated unit tests by saving, executing, and reviewing them.

IntelliTest offers characterization tests, allowing you to understand how code behaves through a suite of traditional unit tests. This suite can serve as a regression suite, aiding in handling the challenges of refactoring legacy or unfamiliar code.

Through guided test input generation, IntelliTest employs an open-code analysis and constraint-solving approach to automatically produce precise test input values, often without requiring user intervention. It generates factories for complex object types and allows customization of these factories to meet specific requirements. Assertions specified as correctness...

In TDD, everything begins with the specification and a thorough understanding of the intended functionality. It’s essential to grasp the meaning of what we want to accomplish in order to write effective tests. With that in mind, let’s establish a scenario for our example.

We’ll create a ValidateMail method that will process email verification. Our goal here is to explore the tools available in Visual Studio to enhance our TDD experience.

Now that we have outlined our requirements, our next step is to begin by creating our unit test project. For this, we’ll choose xUnit, as discussed earlier in this chapter. We will create an empty Class Library Project:

1. We’ll start by writing a test, in our xUnit project, that specifies the behavior or functionality we want to implement:

   [Fact]
   public void ValidateMail_NewUser_ReturnsTrue()
   {
       // Arrange
       var user ...

In this section, we will explore the capabilities of automating testing with Live Unit Test. First, we will learn how to configure Live Unit Testing. Then, we will see how to launch it

Live Unit Testing revolutionizes the testing process by automatically executing unit tests in real-time as you make code changes. This dynamic feature provides developers with the ability to refactor and modify code with increased confidence. By automatically running all affected tests during code editing, Live Unit Testing ensures that any changes made do not introduce regressions.

Furthermore, Live Unit Testing offers insights into the adequacy of test coverage for your code base. It visually presents code coverage in real-time, allowing developers to quickly identify areas where tests are lacking.

Let’s activate this feature by navigating to Test | Live Unit Testing | Start.

Figure 1.18 – Start Live Unit Testing...

In this chapter, we covered the importance of unit testing as a non-regression or development process. We began with a reminder of good unit testing practices and TDD before exploring the functionalities offered by Visual Studio 2022 to enhance our productivity.

We provided an overview of the Test Explorer view, demonstrating how to manage and organize unit tests. Then, we delved into the new IntelliSense feature, which provides tools to easily add non-regression tests to legacy code bases with minimal effort, freeing our minds for future refactoring. Finally, we learned how to leverage IntelliSense tools and Live Unit Testing to facilitate our TDD experience.

In the next chapter, we will dive deeper into the world of debugging and explore all that Visual Studio 2022 offers for advanced strategies.