Rails: How do I write tests for a ruby module?

Question

I would like to know how to write unit tests for a module that is mixed into a couple of classes but don\'t quite know how to go about it:

1. Do I test the instanc

Answer 1

Use inline classes (I am not doing any fancy flexmock or stubba/mocha usage just to show the point)

def test_should_callout_to_foo
   m = Class.new do
     include ModuleUnderTest
     def foo
        3
     end
   end.new
   assert_equal 6, m.foo_multiplied_by_two
 end

Any mocking/stubbing library out there should give you a cleaner way to do this. Also you can use structs:

 instance = Struct.new(:foo).new
 class<

If I have a module that is being used in many places I have a unit test for it which does just that (slide a test object under the module methods and test if the module methods function properly on that object).