Fake DbContext of Entity Framework 4.1 to Test

by

Unfortunately you are not doing it right because that article is wrong. It pretends that FakeContext will make your code unit testable but it will not. Once you expose IDbSet or IQueryable to your controller and you fake the set with in memory collection you can never be sure that your unit test really tests your code. It is very easy to write a LINQ query in your controller which will pass your unit test (because FakeContext uses LINQ-to-Objects) but fails at runtime (because your real context uses LINQ-to-Entities). That makes whole purpose of your unit testing useless.

My opinion: Don’t bother with faking context if you want to expose sets to controller. Instead use integration tests with real database for testing. That is the only way how to validate that LINQ queries defined in controller do what you expect.

Sure, if you want to call just ToList or FirstOrDefault on your sets your FakeContext will serve you well but once you do anything more complex you can find a trap pretty soon (just put the string “Cannot be translated into a store expression” into Google – all these problems will appear only when you run Linq-to-entities but they will pass your tests with Linq-to-objects).

This is quite common question so you can check some other examples:

More Related Contents:

  1. How do you unit test private methods?
  2. Cannot attach the file *.mdf as database
  3. The repository itself is not usually tested?
  4. Can’t find ADO.net Entity Data Model template in VS2017
  5. Where to run a duplicate check for an entity
  6. The model backing the ‘ApplicationDbContext’ context has changed since the database was created
  7. How can I query for null values in entity framework?
  8. .NET Entity Framework and transactions
  9. Can you use Microsoft Entity Framework with Oracle? [closed]
  10. “Items collection must be empty before using ItemsSource.”
  11. How to convert View Model into JSON object in ASP.NET MVC?
  12. C# “internal” access modifier when doing unit testing
  13. ASP.NET MVC – Find Absolute Path to the App_Data folder from Controller
  14. Why is the Visual Studio 2015/2017/2019 Test Runner not discovering my xUnit v2 tests
  15. Is is possible to check if an object is already attached to a data context in Entity Framework?
  16. What are Navigation Properties in Entity Framework for?
  17. LINQ to Entities does not recognize the method Int32 get_Item(Int32)
  18. How to set default value for POCO’s in EF CF?
  19. C# – Asserting two objects are equal in unit tests
  20. What does Html.HiddenFor do?
  21. ASP.NET MVC security patch to version 3.0.0.1 breaks build [duplicate]
  22. How do I improve ASP.NET MVC application performance?
  23. Could not load file or assembly ‘Antlr3.Runtime (1)’ or one of its dependencies
  24. Where is the “Create Unit Tests” selection?
  25. How to throw a SqlException when needed for mocking and unit testing?
  26. ASP.Net MVC Redirect To A Different View
  27. ASP.NET MVC on IIS6
  28. Model First with DbContext, Fails to initialize new DataBase
  29. Validate data using DataAnnotations with WPF & Entity Framework?
  30. Entity framework 4.3 run migrations at application start

Leave a Comment