ruby - Rspec Expect Child Method Invocation Without Causing Parent Method To Fail -

i able test method being called inside method, without testing else.

let's assume have method makes internal service call.

class foo   def self.perform     result = internalservice.call     ...     result.attribute_method # stuff result   end end 

internalservice has of own unit tests, , don't want duplicate tests here. however, still need test internalservice being called.

if use rspec's expect syntax, mock out internalservice.call , rest of method fail because there no result.

allow_any_instance_of(internalservice).to receive(:call).and_return(result) foo.perform  =>  nomethoderror: =>   undefined method `attribute_method' 

if use rspec's allow syntax explicitly return result, expect clause fails because rspec has overridden method.

allow_any_instance_of(internalservice).to receive(:call).and_return(result) expect_any_instance_of(internalservice).to receive(:call) foo.perform  => failure/error: unable find matching line backtrace => 1 instance should have received following message(s) didn't: call 

how can test method being called on object? missing bigger picture here?

try this:

expect(internalservice).to receive(:call).and_call_original foo.perform 

it's class method, right? if not, replace expect expect_any_instance_of.

more and_call_original can found here.