.NET Unit Testing

Introduction to .NET Unit Testing

Unit testing is a fundamental aspect of software development that ensures individual components of an application function as expected. In .NET, unit testing is commonly performed using frameworks like xUnit, NUnit, or MSTest. These frameworks provide a set of tools for writing and executing tests. The core component of these tests is the Assert class, which is used to validate the expected outcomes of a function.

Setting Up a Unit Test Project

To begin unit testing in .NET, you need to set up a test project. This can be easily done using Visual Studio or the .NET CLI. Below is a step-by-step guide to create a test project using the .NET CLI:

This will create a new xUnit test project and add a reference to your application project. Ensure your application project is built and compilable.

Writing Your First Unit Test

Once your test project is set up, you can write your first unit test. In this example, we'll test a simple method that adds two numbers. First, ensure your application has the following method:

Next, create a test class in your test project to validate the Add method:

In this test, we use the Arrange-Act-Assert pattern, a common structure for writing unit tests. Arrange sets up the necessary context, Act executes the method under test, and Assert verifies that the outcome is as expected. In this case, we check that the sum of 2 and 3 equals 5.

Running Your Tests

To run your tests, you can use the .NET CLI or Visual Studio. Using the CLI, navigate to your test project directory and execute:

This command will compile your test project and run all tests, providing feedback on their success or failure. In Visual Studio, you can run tests by opening the Test Explorer and selecting 'Run All'.