Writing integration tests

In the unit tests, we create the instances of the controllers directly. This approach does not consider some features of ASP.NET Core, such as routing, model binding, and validation and so on. To test the application thoroughly, we need to write integration tests. In this section, we will write integration tests for the application.

Unlike unit tests, which focus on isolated units, integration tests focus on the interactions between components. These integration tests may involve different layers, such as the database, the file system, the network, the HTTP request/response pipeline and so on. Integration tests ensure that the components of the application work together as expected. So, normally, integration tests use actual dependencies instead of mocks. Also, integration tests are slower than unit tests because they involve more components. Considering the cost of integration tests, we do not need to write too many integration tests. Instead, we should...