What’s Best for Unit Testing in EF? It depends, dude!

Monday, February 04 2013 - Data Access

This tweet stopped me in my tracks because I couldn’t reply in a tweet:

Stephen Coulson @sdcoulson

@julielerman In your opinion what is the best solution for unit testing#EF dependent code?#MockingFramework? #SQLCE? or other?

It’s a loaded question so I’ll just answer briefly.

First: it depends! :) It always depends.

Do you mean unit tests or integration tests? A unit test shouldn’t be hitting a database.

FAKING FOR UNIT TESTS

I use fakes to avoid hitting a database when I truly want to do a unit test on code that’s trying to do data access. I (and many others) have written extensively about faking with EF. I have some old blog posts and book chapters that do this with EF4 but not using code first or dbcontext.

In my DbContext book I have some examples of faking with DbContext (ala EF4.1 & EF5).

I have a module in one of my Pluralsight courses on testing with EF (Entity Framework in the Enterprise).

MOCKING FRAMEWORKS FOR UNIT TEST

I’ve had a hard time finding good current examples of using mocking frameworks with EF. Typemock has one that’s terribly outdated and not useful. I found one person who’s written a little about using Moq with EF.

SQL CE FOR INTEGRATION TESTS

Sure you can use SQL CE. It’s a perfectly good way to go. Here’s a blog post by Eric Hexter to get you started:

Using sql compact for integration tests with entity framework

CODE FIRST DATABASE INITIALIZATION FOR INTEGRATION TESTS

This is what I use. One of the intializers is “DropCreateDatabaseAlways”. I use that combined with some seed data to refresh my database for each integration test. This is one of the methods I show in my Pluralsight course.

More More More!

There are plenty of other ways to go as well. For example, Lynn Langit has pointed me via twitter to ApprovalTests.

And just watch the comments fill up with other suggestions.

Hope this helps, Stephen! :)

Shout it
#1 henri t on 2.04.2013 at 10:47 AM

i use the effort framework for in memory entity framework integration tests. works the same as real db access, but much much faster and not persistent.

its a bit buggy and not really finished, but has shown great progress the past year.

#2 Lynn Langit on 2.04.2013 at 10:53 AM

you can also use free, open-source ApprovalTests - blog.approvaltests.com/.../whats-new-in-ap

#3 Stephen Coulson on 2.04.2013 at 11:02 AM

Thanks for the amazingly prompt response Julie! I have read chapter 24 in your book "Programming Entity Framework" and I've setup a project using fakes. It works brilliantly but is very laborious. I've been watching the Pluralsight videos on Unit Testing and wondered how well mocking frameworks worked with EF to reduce dev time. I also got reading this article www.codeproject.com/.../Two-strategies- on code project regarding 'Effort' and 'SQL-CE' (which is technically an integration test). Was wondering what your take on this was :-) Thanks again for the reply.

#4 Jim Holmes on 2.04.2013 at 11:27 AM

Mehfuz Hossain has written some posts around mocking and Entity Framework using Telerik's JustMock. Here's one: msmvps.com/.../mocking-constru

#5 El Weinstock-Herman on 2.04.2013 at 6:25 PM

As part of a longer project, I walked through some of the steps of making the MVC Music Store sample (directly interacts w/ EF model from MVC actions as well as other objects) testable: blogs.lessthandot.com/.../continuous-deli

It uses MS Test and Rhino Mocks, but it could just as easily be done with other frameworks/libraries. The full source and history is available (public hg repository on bitbucket).

#6 Julie on 2.04.2013 at 6:35 PM

Thanks Lynn, Jim, Henri and El. This post and comments may end up being a useful resource! :)

#7 Arne on 2.06.2013 at 5:00 PM

Allen Scott has an old but good article using Moq with EF. Would still work with IQueryable and DbContext today. msdn.microsoft.com/.../ff714955.aspx

#8 Rodi on 2.19.2013 at 8:13 AM

Nice write up and a very nice course on Pluralsight.

Be warned to use the abstracted testable DbContext though. Linq to Entities does not implement everything of IQueryable and/or at elast not everything the same as Linq to Objects. This means that your tests could say everything is fine, while the code will not work as expected when using the real Entity Framework DbContext.

Just make sure that you back up the Unit Tests with proper Integration Tests that do hit EF with the real database.

#9 Jesper on 4.09.2013 at 10:27 AM

Given that Entity Framework lends itself well to testing when an in-memory provider is used, why does the Entity Framework team not develop a supported in-memory provider with complete LINQ support and semantics for use there?

I'm currently using Effort (effort.codeplex.com) and can put logic in methods that I can use in production code as well as in tests, but that only works as long as Effort tracks EF developments.

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