Testing controllers using the WebApplicationFactory<T> class

The ASP.NET Core Framework provides a way to perform integration tests using the WebApplicationFactory<T> class. This class allows us to create a new TestServer that emulates a real HTTP server in a separate process. Therefore, it is possible to test our ItemController by calling it through an HttpClient instance provided by the factory. It is essential to note that WebApplicationFactory is a generic class and that it accepts a TEntryPoint type, which is represented by the Startup class of our web service. Before proceeding with the implementation of the test class, let's create a new project in the tests folder that will contain all tests related to the Catalog.API project. Therefore, we can execute the following commands inside the tests folder:

dotnet new xunit -n Catalog.API.Tests
cd Catalog.API.Tests...