CODEWITHSUNDEEP
ruby-on-railsrspecrspec2
Cory
Cory

Reputation: 2538

Rspec and Rails Controller Expectations

All,

Having some issues with a test much like what follows:

it "does something" do
  controller.should_receive(:some_method).once

  expect {
    post :create, some_params_hash, some_session_hash
  }.to change(Something, :count).by(1)
end

Controller on the rails side - rough example:

class SomethingsController
  before_filter :some_method

  def create
    respond_with Something.create params[:something]
  end

  def some_method
    puts 'some_method'
  end
end

This is all well and good and works just fine if I remove the controller.should_receive expectation. If I leave the expectation in place - the test fails.

What's strange is it isn't failing on an unsatisfied expectation - it actually seems to meet the should_receive(:some_method) expectation - it's just that the record create and subsequent change evaluation fail.

So - question:

Is this the proper way to specify expectations on the controller that is invoked as part of this test??

Thanks for any help!

Upvotes: 1

Views: 1522

Answers (1)

Rob Davis
Rob Davis

Reputation: 15772

A common rspec error is thinking that a method expectation like the one set up by your should_receive simply monitors the application to make sure certain things happen. But actually it inserts itself into the flow and replaces the method entirely.

So your controller's some_method will be replaced by one that does nothing but return nil. And a before filter that returns nil will stop all processing. Your action is never called.

Change your expectation to this:

controller.should_receive(:some_method).once.and_return true

Also note that your example is testing two things -- it's making sure your action calls some_method and it's making sure the number of persisted Somethings increases by one. That's fine, but if you really only intended to check the latter, you could use a stub instead of an expectation, which is a little more compact:

controller.stub some_method: true

UPDATE: I should add that in recent versions of Rails, the return value of a controller filter is ignored. (The filter can prevent the action from executing just by rendering something.) However, the principle of rspec's should_receive replacing your method is still true and generally applicable.

Upvotes: 1

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