Mirage vs FactoryGuyfor data mocking

I am in the process of setting up ember tests for the first time and one big question is how to deal with data mocking.

I was wondering if anyone had any insight as to pros and cons for Mirage and Factory Guy

I know mirage is based on mocking an entire server which seems good in the sense that it matches reality a little bit more closely but it also seems like extra work both in writing the mocks and instantiating them.

I was wondering if anyone had any perspective on that trade off or any other anecdotal experience about which they had liked more and why.

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In my opinion, the difference of features is blurring between the two, but the API and history makes it all. Here’s a list of comparison points that I can think of:

  • Mirage always focused on mocking the server, which makes it agnostic to Ember adapters. Mirage goes with or without Ember Data.
  • FactoryGuy focuses on Ember Data. If you don’t use EmberData, move away from FactoryGuy.


  • FactoryGuy seems to have a nicer/more complete API for handling HTTP errors in tests. Or at the very least, closer to the standard API we’re used in testing our Ember apps.
  • But I didn’t notice any difference in the feature set on mocking HTTP behaviour.


  • Mirage started with Fixtures and added functionnality up to factories along the way.
  • FactoryGuy started with factories in mind, they’re more powerful, with traits and globally better specifications of “what I want to test now”. “Simple” fixtures are possible but it’s ridiculous tu use FG with static fixtures (which is both a pro and a con).


  • FactoryGuy allows for a greater variability of your tests, but comes at a cost.
  • Mirage is simpler, but edge cases will stay hidden from testing until you manually add them.


tl;dr; Mirage is easier and faster, but FactoryGuy more powerful and heavyweight.

my personal preference:

I personnally went with Mirage and apart from the management of relationships (which is getting better and better), I never had to complain. FactoryGuy is a very muscular beast, but I’m afraid at some point you’re in need to test the factories you use for testing, if you see what I mean.

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Excellent and very in depth comparison! I think I was conceiving of what their strong points were incorrectly in some cases so this was very clarifying.