RSpec存根服务对象方法

Question

I'm having an issue with stubbing out a call to a service object (QuickbooksService) from an AR object. As far as I can tell the method should be stubbed properly and return the value I'm specifying but when I run the spec I can see the method being called and failing.

Here's the class definition of the object I'm testing.

class Order < ActiveRecord::Base
  def create_invoice
    QuickbooksService.new(:estimate).create_invoice(arg1, arg2, arg3)
  end
end

And from order_spec

describe("#create_invoice") do
  expect(QuickbooksService.new(:estimate)).to receive(:create_invoice).and_return(1)
end

I've also tried

allow(QuickbooksService.new(:estimate)).to receive(:form_invoice_create).with(anything()).and_return(1)

So instead of returning 1 the create_invoice method is being executed inside of QuickbooksService. Any insight would be appreciated!

Answer 1

The problem you are having is that you are stubbing a seperate instance. ie When you define the expectation, you telling it to expect that a particular instance receives a call to the method, but when the code is executed, it is creating a different instance. What you need to do is allow any instance to receive the method call. Something like allow_any_instance_of(QuickbooksService).to receive(:invoice_create) will work, but it is much better practice to create a double, something like:

let(:quickbooks_service) { instance_double(QuickbooksService) }

describe("#create_invoice") do
  before { allow(quickbooks_service).to receive(:create_invoice).and_return(1) }

  it "Creates quickbook invoice" do
    order.create_invoice
    expect(quickbooks_service).to have_received(:create_invoice)
  end
end

See: https://relishapp.com/rspec/rspec-mocks/docs

Answer 2

The problem is that you are instantiating the class while stubbing it allow(QuickbooksService.new(:estimate)).to receive(:form_invoice_create).with(anything()).and_return(1)

Try this:

allow_any_instance_of(QuickbooksService).to receive(:form_invoice_create).with(anything()).and_return(1)

Answer 3

Found this while learning about rspec mocks and stubs. On Nicholas.V's answer 1 , don't we also need to do

QuickbooksService.stub(:new).and_return(quickbooks_service)

before calling order.create_invoice ?