While writing tests, I stopped at trying to test Service in another Service. In such a situation, I should probably just check if Service has been called because it has already been tested elsewhere. I did a little research on the Internet and found something like have_received but I have no idea how to use it in my example.
check_service.rb
Class CheckService
def initialize(params)
@params = params
end
def self.call(params)
new(params).call
end
def call
CheckUser.call(params[:user_id])
end
end
check_service_spec.rb
...
describe 'call' do
let(:result) { CheckService.call(params) }
let(:params) { { user_id: "100" } }
let(:check_user) { instance_double(CheckUser) }
before do
allow(check_user).to receive(:call).and_return(true)
end
it do
result
expect(check_user).to have_received(:call)
end
end
...
I was trying something like this (it's simple example), but I get error:
(InstanceDouble(CheckUser) (anonymous)).call(*(any args))
expected: 1 time with any arguments
received: 0 times with any arguments
Is there any option to test situation I presented?
Short anwser
describe 'call' do
let(:result) { CheckService.call(params) }
let(:params) { { user_id: "100" } }
## let(:check_user) { instance_double(CheckUser) } delete this
before do
allow(CheckUser).to receive(:call).and_return(true)
end
it do
result
expect(CheckUser).to have_received(:call)
end
end
Alternative
I think a better way to test this is to use DI (Dependency Injection), so you pass CheckUser as a dependency to CheckService. I prefer to write the whole test inside the it block too!
class CheckService
def initialize(params, check_handler:)
@params = params
@check_handler = check_handler
end
def self.call(params, check_handler: CheckUser)
new(params, check_handler: check_handler).call
end
def call
@check_handler.call(@params[:user_id])
end
end
describe 'call' do
it 'check user with params' do
check_user = class_double(CheckUser)
allow(check_user).to receive(:call).and_return(true)
params = { user_id: "100" }
CheckService.call(params, check_handler: check_user)
expect(check_user).to have_received(:call)
end
end
A blog post to read more about -> https://blog.testdouble.com/posts/2018-05-17-do-we-need-dependency-injection-in-ruby/