Test that the polling header is set correctly

- Move shared examples into seperate file

app/controllers/projects/error_tracking/base_controller.rb

+# frozen_string_literal: true
+
+class Projects::ErrorTracking::BaseController < Projects::ApplicationController
+  POLLING_INTERVAL = 1_000
+
+  def set_polling_interval
+    Gitlab::PollingInterval.set_header(response, interval: POLLING_INTERVAL)
+  end
+end

app/controllers/projects/error_tracking/stack_traces_controller.rb

@@ -2,10 +2,10 @@
 
 module Projects
   module ErrorTracking
-    class StackTracesController < Projects::ApplicationController
+    class StackTracesController < Projects::ErrorTracking::BaseController
       respond_to :json
 
-      before_action :authorize_read_sentry_issue!
+      before_action :authorize_read_sentry_issue!, :set_polling_interval
 
       def index
         result = fetch_latest_event_issue

app/controllers/projects/error_tracking_controller.rb

 # frozen_string_literal: true
 
-class Projects::ErrorTrackingController < Projects::ApplicationController
+class Projects::ErrorTrackingController < Projects::ErrorTracking::BaseController
   before_action :authorize_read_sentry_issue!
   before_action :set_issue_id, only: :details
 
-  POLLING_INTERVAL = 10_000
-
   def index
     respond_to do |format|
       format.html
@@ -20,6 +18,7 @@ class Projects::ErrorTrackingController < Projects::ApplicationController
     respond_to do |format|
       format.html
       format.json do
+        set_polling_interval
         render_issue_detail_json
       end
     end
@@ -74,10 +73,6 @@ class Projects::ErrorTrackingController < Projects::ApplicationController
     @issue_id = issue_details_params[:issue_id]
   end
 
-  def set_polling_interval
-    Gitlab::PollingInterval.set_header(response, interval: POLLING_INTERVAL)
-  end
-
   def serialize_errors(errors)
     ErrorTracking::ErrorSerializer
       .new(project: project, user: current_user)

spec/controllers/projects/error_tracking/stack_traces_controller_spec.rb

@@ -34,6 +34,8 @@ describe Projects::ErrorTracking::StackTracesController do
       it 'responds with no data' do
         expect(response).to have_gitlab_http_status(:no_content)
       end
+
+      it_behaves_like 'sets the polling header'
     end
 
     context 'service result is successful' do
@@ -53,6 +55,8 @@ describe Projects::ErrorTracking::StackTracesController do
           Gitlab::ErrorTracking::StackTraceHighlightDecorator.decorate(error_event).as_json
         )
       end
+
+      it_behaves_like 'sets the polling header'
     end
 
     context 'service result is erroneous' do

spec/controllers/projects/error_tracking_controller_spec.rb

@@ -91,13 +91,13 @@ describe Projects::ErrorTrackingController do
               .and_return(status: :success, issues: [error], pagination: {})
             expect(list_issues_service).to receive(:external_url)
               .and_return(external_url)
+
+            get :index, params: params
           end
 
           let(:error) { build(:error_tracking_error) }
 
           it 'returns a list of errors' do
-            get :index, params: params
-
             expect(response).to have_gitlab_http_status(:ok)
             expect(response).to match_response_schema('error_tracking/index')
             expect(json_response).to eq(
@@ -106,6 +106,8 @@ describe Projects::ErrorTrackingController do
               'external_url' => external_url
             )
           end
+
+          it_behaves_like 'sets the polling header'
         end
       end
 
@@ -201,30 +203,33 @@ describe Projects::ErrorTrackingController do
         before do
           expect(issue_details_service).to receive(:execute)
             .and_return(status: :error, http_status: :no_content)
+          get :details, params: issue_params(issue_id: issue_id, format: :json)
         end
 
         it 'returns no data' do
-          get :details, params: issue_params(issue_id: issue_id, format: :json)
-
           expect(response).to have_gitlab_http_status(:no_content)
         end
+
+        it_behaves_like 'sets the polling header'
       end
 
       context 'service result is successful' do
         before do
           expect(issue_details_service).to receive(:execute)
             .and_return(status: :success, issue: error)
+
+          get :details, params: issue_params(issue_id: issue_id, format: :json)
         end
 
         let(:error) { build(:detailed_error_tracking_error) }
 
         it 'returns an error' do
-          get :details, params: issue_params(issue_id: issue_id, format: :json)
-
           expect(response).to have_gitlab_http_status(:ok)
           expect(response).to match_response_schema('error_tracking/issue_detailed')
           expect(json_response['error']).to eq(error.as_json)
         end
+
+        it_behaves_like 'sets the polling header'
       end
 
       context 'service result is erroneous' do

spec/support/shared_examples/controllers/error_tracking_shared_examples.rb

+# frozen_string_literal: true
+
+shared_examples 'sets the polling header' do
+  subject { response.headers[Gitlab::PollingInterval::HEADER_NAME] }
+
+  it { is_expected.to eq '1000'}
+end