unexpected message :body with (no args) when using a double

[belgoros]

I have a weird behaviour when running a spec separately passes bu t fails when running all the tests.

Here is the spec to test a service:

require 'rails_helper'


RSpec.describe SportsService do
  let(:user) { create(:user)}


  describe '#call' do
    it 'raises an error if the request is failed' do
      service = described_class.new(user: user)
      allow(service).to receive(:execute_request).with(anything).and_return(failed_response)


      expect { service.call }.to raise_error ExceptionHandler::AuthenticationError
    end


    it 'send successful response' do
      service = described_class.new(user: user)
      allow(service).to receive(:execute_request).with(anything).and_return(successful_response)
      sports_values_to_check = service.call.map {|sport| {id: sport.id, label: sport.label}}
      expect(sports_values_to_check).to include(id: 1, label: 'sport-1')
    end
  end
end


def failed_response
  double(:response, code: 100)
end


def successful_response
  double(:response, code: 200, body: '[{"sport_id": 1, "label": "sport-1"}, {"sport_id": 2, "label": "sport-2"}]')
end

The failing example is "send successful response" that fails with a message:

 1) SportsService#call send successful response

     Failure/Error: create_sports(response.body)

       #<Double :response> received unexpected message :body with (no args)

     # ./app/services/sports_service.rb:17:in `call'

     # ./spec/services/sports_service_spec.rb:17:in `block (3 levels) in <main>'

Why RSpec does not find body defined on my double ? Thank you.

[belgoros]

I think I have an idea.

I'm using services and declare them in an initializer created in  config/initilizers/service_provider.rb as follows:

class ServiceProvider
  @services = {}


  def self.register(key, klass)
    return false if @services.key?(key) && !Rails.env.test?
    @services[key] = klass
  end


  def self.get(key)
    @services[key]
  end


  def self.[](key)
    get(key)
  end


  def self.finished_loading
    @services.freeze unless Rails.env.test?
  end
end


... #other services being declared here as well
ServiceProvider.register :sports_service, SportsService


ServiceProvider.finished_loading

And in sports_controller I'm getting the service like that:

module V1
  class SportsController < ApplicationController


    def index
      json_response sports_service.call
    end


    private


    def sports_service_class
      @sports_service_class ||= ServiceProvider.get(:sports_service)
    end


    def sports_service
      @sports_service ||= sports_service_class.new(user: current_user)
    end
  end
end

I think I'll have to create and register for such a test a dummy SportsService directly in my rspec file testing the service, somethig like that (spec/services/sports_service_spec):

require 'rails_helper'


SuccessfulUserInfoService = Struct.new(:user, keyword_init: true) do
  include ServiceClient


  def call
    true
  end
end

RSpec.describe SportsService do
  let(:user) { create(:user)}


  describe '#call' do

    after(:each) do
      ServiceProvider.register(:sports_service, SportsService) # putting back the original service
    end
...

This is just an idea, have not tested it yet. May be I'm testing the wrong thing ? I'd like to test the result returned by service's #call method

[belgoros]

I forgot to put the rest of the example (see the dummy service initialization):

it 'sends a successful response with sports data' do
      ServiceProvider.register(:sports_service, SuccessfulSportsService)
      service = ServiceProvider.get(:sports_service)
      allow(service).to receive(:execute_request).with(anything).and_return(successful_response)
     
      service_data = service.call
      sports_values_to_check = service_data.map {|sport| {id: sport.id, label: sport.label}}

[Jon Rowe]

Its looks like your doubles are some how leaking between examples, I’d wager its something to do with your service injector but I’m unsure without a proper example.

Cheers

Jon Rowe

---------------------------

ma...@jonrowe.co.uk

jonrowe.co.uk

[belgoros]

On Tuesday, 23 October 2018 21:52:38 UTC+2, Jon Rowe wrote:

Its looks like your doubles are some how leaking between examples, I’d wager its something to do with your service injector but I’m unsure without a proper example.

Cheers

Jon Rowe

I think the problem comes from #successful_response method, - I checked and discovered that I had 2 ones in different specs, both are declared outside of main RSpec.describe block like that:

#spec_one_spec.rb

RSpec.describe 'SpecOne' do

...# some examples

end

def successful_response

  double(:response, code: 200)

end

#spec_two_spec.rb

RSpec.describe 'SpecTwo' do

...# some examples

end

def successful_response

  double(:response, code: 200, body: '[{"sport_id": 1, "label": "sport-1"}, {"sport_id": 2, "label": "sport-2"}]')

end

What is the rule of thumb to declare such a kind of helper methods ? Should we put them inside the main RSpec.describe block, outside, make them private ?

Cheers

[belgoros]

On Wednesday, 24 October 2018 09:04:51 UTC+2, belgoros wrote:

On Tuesday, 23 October 2018 21:52:38 UTC+2, Jon Rowe wrote:

Its looks like your doubles are some how leaking between examples, I’d wager its something to do with your service injector but I’m unsure without a proper example.

Cheers

Jon Rowe

I think the problem comes from #successful_response method, - I checked and discovered that I had 2 ones in different specs, both are declared outside of main RSpec.describe block like that:

#spec_one_spec.rb

RSpec.describe 'SpecOne' do

...# some examples

end

def successful_response

  double(:response, code: 200)

end

#spec_two_spec.rb

RSpec.describe 'SpecTwo' do

...# some examples

end

def successful_response

  double(:response, code: 200, body: '[{"sport_id": 1, "label": "sport-1"}, {"sport_id": 2, "label": "sport-2"}]')

end

What is the rule of thumb to declare such a kind of helper methods ? Should we put them inside the main RSpec.describe block, outside, make them private ?

Cheers

I moved the above methods inside the main RSpec.describe block and all the tests passed. So should we always keep them there or there is another best practice ?

Thank you. 

[belgoros]

I re-opened the Effective Testing with RSpec-3 book by Myron Marston & Ian Dees, and on page 11 you can already find the explanation:

Each example group is a Ruby class, which means that we can define methods on it. Right after the describe line, add the following code....

def sandwich 

  Sandwich.new('delicious', [])

end 

So I refactored all the examples to fix that. Hope this helps.

[Jon Rowe]

Ah yes absolutely that was the cause. 

When you define methods outside of an RSpec describe (which creates a class) you are defining methods on `main`. So essentially you overwrote your method definition when you loaded all the specs and its just luck which one was active.

Glad you solved it!

Cheers

Jon Rowe

---------------------------

ma...@jonrowe.co.uk

jonrowe.co.uk