Refactor start_retirement method for Service Retirement.

This PR is based on the issue below.
ManageIQ/manageiq#12038

@miq-bot add_label refactoring
@miq-bot assign @tinaafitz

Added test for service_retire_task = nil, was missing this in coverage
Added test for retirement_state = 'retiring' as requested

Modified method as requested
Deleted comment and blank line
Removed extra log messages because Raise doesn't need them
Fixed rob error
Fixed raise logic to 1 line

content/automate/ManageIQ/Service/Retirement/StateMachines/Methods.class/__methods__/start_retirement.rb

@@ -1,32 +1,57 @@
 #
 # Description: This method sets the retirement_state to retiring
 #
+module ManageIQ
+  module Automate
+    module Service
+      module Retirement
+        module StateMachines
+          module Methods
+            class StartRetirement
+              def initialize(handle = $evm)
+                @handle = handle
+              end
 
-service = $evm.root['service']
-if service.nil?
-  $evm.log('error', "Service Object not found")
-  exit MIQ_ABORT
-end
+              def main
+                @handle.log('info', "Service before start_retirement: #{service.inspect} ")
+                start_retirement(service)
+                @handle.log('info', "Service after start_retirement: #{service.inspect} ")
+              end
 
-$evm.log('info', "Service before start_retirement: #{service.inspect} ")
+              private
 
-if service.retired?
-  $evm.log('error', "Service is already retired. Aborting current State Machine.")
-  exit MIQ_ABORT
-end
+              def service
+                @handle.root["service"].tap do |service|
+                  raise 'Service Object not found' if service.nil?
+                end
+              end
 
-if service.retiring?
-  $evm.log('error', "Service is in the process of being retired. Aborting current State Machine.")
-  exit MIQ_ABORT
-end
+              def start_retirement(service)
+                service_validation(service)
+                @handle.create_notification(:type => :service_retiring, :subject => service)
 
-unless $evm.root['service_retire_task']
-  $evm.log(:error, "Service retire task not found")
-  $evm.log(:error, "The old style retirement is incompatible with the new retirement state machine.")
-  exit(MIQ_ABORT)
-end
+                service.start_retirement
+              end
 
-$evm.create_notification(:type => :service_retiring, :subject => service)
-service.start_retirement
+              def service_validation(service)
+                if service.retired?
+                  raise 'Service is already retired'
+                end
+
+                if service.retiring?
+                  raise 'Service is already in the process of being retired'
+                end
+
+                unless @handle.root['service_retire_task']
+                  raise 'Service retire task not found, The old style retirement is incompatible with the new retirement state machine.'
+                end
+              end
+            end
+          end
+        end
+      end
+    end
+  end
+end
 
-$evm.log('info', "Service after start_retirement: #{service.inspect} ")
+ManageIQ::Automate::Service::Retirement::StateMachines::Methods::StartRetirement.new.main

spec/content/automate/ManageIQ/Service/Retirement/StateMachines/Methods.class/__methods__/start_retirement_spec.rb

@@ -0,0 +1,42 @@
+require_domain_file
+
+describe ManageIQ::Automate::Service::Retirement::StateMachines::Methods::StartRetirement do
+  let(:admin) { FactoryBot.create(:user_admin) }
+  let(:request) { FactoryBot.create(:service_retire_request, :requester => admin) }
+  let(:service) { FactoryBot.create(:service) }
+  let(:task) { FactoryBot.create(:service_retire_task, :destination => service, :miq_request => request) }
+  let(:svc_task) { MiqAeMethodService::MiqAeServiceServiceRetireTask.find(task.id) }
+  let(:svc_service) { MiqAeMethodService::MiqAeServiceService.find(service.id) }
+  let(:root_object) do
+    Spec::Support::MiqAeMockObject.new('service'             => svc_service,
+                                       'service_retire_task' => svc_task,
+                                       'service_action'      => 'Retirement')
+  end
+  let(:ae_service) { Spec::Support::MiqAeMockService.new(root_object) }
+
+  it "without service" do
+    ae_service.root['service'] = nil
+    expect { described_class.new(ae_service).main }.to raise_error('Service Object not found')
+  end
+
+  it "without task" do
+    ae_service.root['service_retire_task'] = nil
+    expect { described_class.new(ae_service).main }.to raise_error('Service retire task not found, The old style retirement is incompatible with the new retirement state machine.')
+  end
+
+  it "with retired service" do
+    svc_service.finish_retirement
+    expect { described_class.new(ae_service).main }.to raise_error('Service is already retired')
+  end
+
+  it "with retiring service" do
+    svc_service.start_retirement
+    expect { described_class.new(ae_service).main }.to raise_error('Service is already in the process of being retired')
+  end
+
+  it "starts retirement" do
+    expect(ae_service).to receive(:create_notification).with(:type => :service_retiring, :subject => svc_service)
+    described_class.new(ae_service).main
+    expect(svc_service.retirement_state).to eq('retiring')
+  end
+end