When we have to test methods that involves Entity Framework, a typical choice that we have to face is use integration tests, with an effective database, or unit tests.

If we choice the first option, with a database like SQL LocalDB, we’ll have performance problems because the cost of the database creation and the data inserts in the test startup is very high, and in order to guarantee the initial conditions we’ll have to do it for each test.

What we can do is use a mock framework that help us to mockup the entity framework context; it would be an in-memory db context, like the in-memory db context of .NET Core, that we have seen in this post.

The factory

In pratice, mocking a class means substitute the real implementation of a method with our custom behaviour; what we can do for every method of the class is…