Record action when namespace trial starts

This creates an onboarding action for a namespace when the trial starts.
We track these actions to have an onboarding experience for namespaces.

ee/app/services/gitlab_subscriptions/apply_trial_service.rb

@@ -6,6 +6,9 @@ module GitlabSubscriptions
       response = client.generate_trial(apply_trial_params)
 
       if response[:success]
+        namespace_id = apply_trial_params.dig(:trial_user, :namespace_id)
+        record_onboarding_progress(namespace_id) if namespace_id
+
         { success: true }
       else
         { success: false, errors: response.dig(:data, :errors) }
@@ -17,5 +20,12 @@ module GitlabSubscriptions
     def client
       Gitlab::SubscriptionPortal::Client
     end
+
+    def record_onboarding_progress(namespace_id)
+      namespace = Namespace.find_by(id: namespace_id) # rubocop: disable CodeReuse/ActiveRecord
+      return unless namespace
+
+      OnboardingProgressService.new(namespace).execute(action: :trial_started)
+    end
   end
 end

ee/spec/services/gitlab_subscriptions/apply_trial_service_spec.rb

+# frozen_string_literal: true
+
+require 'spec_helper'
+
+RSpec.describe GitlabSubscriptions::ApplyTrialService do
+  subject(:execute) { described_class.new.execute(apply_trial_params) }
+
+  let_it_be(:namespace) { create(:namespace) }
+  let(:apply_trial_params) do
+    {
+      trial_user: {
+        namespace_id: namespace.id
+      }
+    }
+  end
+
+  describe '#execute' do
+    before do
+      allow(Gitlab::SubscriptionPortal::Client).to receive(:generate_trial).and_return(response)
+    end
+
+    context 'trial applied successfully' do
+      let(:response) { { success: true }}
+
+      it 'returns success: true' do
+        expect(execute).to eq({ success: true })
+      end
+
+      it 'records a namespace onboarding progress action' do
+        expect_next_instance_of(OnboardingProgressService) do |service|
+          expect(service).to receive(:execute).with(action: :trial_started)
+        end
+
+        execute
+      end
+    end
+
+    context 'error while applying the trial' do
+      let(:response) { { success: false, data: { errors: ['some error'] } }}
+
+      it 'returns success: false with errors' do
+        expected_response = {
+          success: false,
+          errors: ['some error']
+        }
+
+        expect(execute).to eq(expected_response)
+      end
+
+      it 'does not record a namespace onboarding progress action' do
+        expect(OnboardingProgressService).not_to receive(:new)
+
+        execute
+      end
+    end
+  end
+end