ruby on rails - How to test model's callback method independently? -

i had method in model:

class article < activerecord::base   def do_something   end end 

i had unit test method:

# spec/models/article_spec.rb describe "#do_something"   @article = factorygirl.create(:article)   "should work expected"     @article.do_something     expect(@article).to have_something   end   # ...several other examples different cases end 

everything fine until found it's better move method after_save callback:

class article < activerecord::base   after_save :do_something    def do_something   end end 

now tests method broken. have fix by:

• no more specific call do_something because create or save trigger method well, or i'll meet duplicate db actions.
• change create build
• test respond_to

• use general model.save instead of individual method call model.do_something

  describe "#do_something"   @article = factorygirl.build(:article)   "should work expected"     expect{@article.save}.not_to raise_error     expect(@article).to have_something     expect(@article).to respond_to(:do_something)   end end 

the test passed concern it's no longer specific method. effect mixed other callbacks if more added.

my question is, there beautiful way test model's instance methods independently becoming callback?

callback , callback behavior independent tests. if want check after_save callback, need think of 2 things:

1. is callback being fired right events?
2. is called function doing right thing?

assume have article class many callbacks, how test:

class article < activerecord::base   after_save    :do_something   after_destroy :do_something_else   ... end  "triggers do_something on save"   expect(@article).to receive(:do_something)   @article.save end  "triggers do_something_else on destroy"   expect(@article).to receive(:do_something_else)   @article.destroy end  "#do_something should work expected"   # actual tests do_something method end 

this decouples callbacks behavior. example, trigger same callback method article.do_something when other related object updated, user.before_save { user.article.do_something }. accomodate those.

so, keep testing methods usual. worry callbacks separately.

edit: typos , potential misconceptions edit: change "do something" "trigger something"