Make notification_service spec DRYer by making some tests reusable

The spec for 'participatns' notifications in notification_service for both
issue and merge_request is pretty simple but it was fully copied without sagnificant changes
8 times (!!!) for EVERY situation you need to notify this group of user which caused to file
to extra growth and not being very DRY. And I love DRY. Since the spec is already too messy  and
most likely gonna to increase the size nearest time, I decided to refactor those parts.

changelogs/unreleased/get-rid-of-water-from-notification_service_spec-to-make-it-DRY.yml

+---
+title: Make notification_service spec DRYer by making test reusable
+merge_request: 
+author: YarNayar

spec/services/notification_service_spec.rb

@@ -33,6 +33,49 @@ describe NotificationService, services: true do
     end
   end
 
+  # Next shared examples are intended to test notifications of "participants"
+  #
+  # they take the following parameters:
+  # * issuable
+  # * notification trigger
+  # * participant
+  #
+  shared_examples 'participating by note notification' do
+    it 'emails the participant' do
+      create(:note_on_issue, noteable: issuable, project_id: project.id, note: 'anything', author: participant)
+
+      notification_trigger
+
+      should_email(participant)
+    end
+  end
+
+  shared_examples 'participating by assignee notification' do
+    it 'emails the participant' do
+      issuable.update_attribute(:assignee, participant)
+
+      notification_trigger
+
+      should_email(participant)
+    end
+  end
+
+  shared_examples 'participating by author notification' do
+    it 'emails the participant' do
+      issuable.author = participant
+
+      notification_trigger
+
+      should_email(participant)
+    end
+  end
+
+  shared_examples_for 'participating notifications' do
+    it_should_behave_like 'participating by note notification'
+    it_should_behave_like 'participating by author notification'
+    it_should_behave_like 'participating by assignee notification'
+  end
+
   describe 'Keys' do
     describe '#new_key' do
       let!(:key) { create(:personal_key) }
@@ -539,32 +582,10 @@ describe NotificationService, services: true do
         should_not_email(@u_lazy_participant)
       end
 
-      context 'participating' do
-        context 'by assignee' do
-          before do
-            issue.update_attribute(:assignee, @u_lazy_participant)
-            notification.reassigned_issue(issue, @u_disabled)
-          end
-
-          it { should_email(@u_lazy_participant) }
-        end
-
-        context 'by note' do
-          let!(:note) { create(:note_on_issue, noteable: issue, project_id: issue.project_id, note: 'anything', author: @u_lazy_participant) }
-
-          before { notification.reassigned_issue(issue, @u_disabled) }
-
-          it { should_email(@u_lazy_participant) }
-        end
-
-        context 'by author' do
-          before do
-            issue.author = @u_lazy_participant
-            notification.reassigned_issue(issue, @u_disabled)
-          end
-
-          it { should_email(@u_lazy_participant) }
-        end
+      it_behaves_like 'participating notifications' do
+        let(:participant) { create(:user, username: 'user-participant') }
+        let(:issuable) { issue }
+        let(:notification_trigger) { notification.reassigned_issue(issue, @u_disabled) }
       end
     end
 
@@ -671,32 +692,10 @@ describe NotificationService, services: true do
         should_not_email(@u_lazy_participant)
       end
 
-      context 'participating' do
-        context 'by assignee' do
-          before do
-            issue.update_attribute(:assignee, @u_lazy_participant)
-            notification.close_issue(issue, @u_disabled)
-          end
-
-          it { should_email(@u_lazy_participant) }
-        end
-
-        context 'by note' do
-          let!(:note) { create(:note_on_issue, noteable: issue, project_id: issue.project_id, note: 'anything', author: @u_lazy_participant) }
-
-          before { notification.close_issue(issue, @u_disabled) }
-
-          it { should_email(@u_lazy_participant) }
-        end
-
-        context 'by author' do
-          before do
-            issue.author = @u_lazy_participant
-            notification.close_issue(issue, @u_disabled)
-          end
-
-          it { should_email(@u_lazy_participant) }
-        end
+      it_behaves_like 'participating notifications' do
+        let(:participant) { create(:user, username: 'user-participant') }
+        let(:issuable) { issue }
+        let(:notification_trigger) { notification.close_issue(issue, @u_disabled) }
       end
     end
 
@@ -723,32 +722,10 @@ describe NotificationService, services: true do
         should_not_email(@u_lazy_participant)
       end
 
-      context 'participating' do
-        context 'by assignee' do
-          before do
-            issue.update_attribute(:assignee, @u_lazy_participant)
-            notification.reopen_issue(issue, @u_disabled)
-          end
-
-          it { should_email(@u_lazy_participant) }
-        end
-
-        context 'by note' do
-          let!(:note) { create(:note_on_issue, noteable: issue, project_id: issue.project_id, note: 'anything', author: @u_lazy_participant) }
-
-          before { notification.reopen_issue(issue, @u_disabled) }
-
-          it { should_email(@u_lazy_participant) }
-        end
-
-        context 'by author' do
-          before do
-            issue.author = @u_lazy_participant
-            notification.reopen_issue(issue, @u_disabled)
-          end
-
-          it { should_email(@u_lazy_participant) }
-        end
+      it_behaves_like 'participating notifications' do
+        let(:participant) { create(:user, username: 'user-participant') }
+        let(:issuable) { issue }
+        let(:notification_trigger) { notification.reopen_issue(issue, @u_disabled) }
       end
     end
   end
@@ -809,31 +786,28 @@ describe NotificationService, services: true do
       end
 
       context 'participating' do
-        context 'by assignee' do
-          before do
-            merge_request.update_attribute(:assignee, @u_lazy_participant)
-            notification.new_merge_request(merge_request, @u_disabled)
-          end
-
-          it { should_email(@u_lazy_participant) }
+        it_should_behave_like 'participating by assignee notification' do
+          let(:participant) { create(:user, username: 'user-participant')}
+          let(:issuable) { merge_request }
+          let(:notification_trigger) { notification.new_merge_request(merge_request, @u_disabled) }
         end
 
-        context 'by note' do
-          let!(:note) { create(:note_on_issue, noteable: merge_request, project_id: project.id, note: 'anything', author: @u_lazy_participant) }
-
-          before { notification.new_merge_request(merge_request, @u_disabled) }
-
-          it { should_email(@u_lazy_participant) }
+        it_should_behave_like 'participating by note notification' do
+          let(:participant) { create(:user, username: 'user-participant')}
+          let(:issuable) { merge_request }
+          let(:notification_trigger) { notification.new_merge_request(merge_request, @u_disabled) }
         end
 
         context 'by author' do
+          let(:participant) { create(:user, username: 'user-participant')}
+
           before do
-            merge_request.author = @u_lazy_participant
+            merge_request.author = participant
             merge_request.save
             notification.new_merge_request(merge_request, @u_disabled)
           end
 
-          it { should_not_email(@u_lazy_participant) }
+          it { should_not_email(participant) }
         end
       end
     end
@@ -868,33 +842,10 @@ describe NotificationService, services: true do
         should_not_email(@u_lazy_participant)
       end
 
-      context 'participating' do
-        context 'by assignee' do
-          before do
-            merge_request.update_attribute(:assignee, @u_lazy_participant)
-            notification.reassigned_merge_request(merge_request, @u_disabled)
-          end
-
-          it { should_email(@u_lazy_participant) }
-        end
-
-        context 'by note' do
-          let!(:note) { create(:note_on_issue, noteable: merge_request, project_id: project.id, note: 'anything', author: @u_lazy_participant) }
-
-          before { notification.reassigned_merge_request(merge_request, @u_disabled) }
-
-          it { should_email(@u_lazy_participant) }
-        end
-
-        context 'by author' do
-          before do
-            merge_request.author = @u_lazy_participant
-            merge_request.save
-            notification.reassigned_merge_request(merge_request, @u_disabled)
-          end
-
-          it { should_email(@u_lazy_participant) }
-        end
+      it_behaves_like 'participating notifications' do
+        let(:participant) { create(:user, username: 'user-participant') }
+        let(:issuable) { merge_request }
+        let(:notification_trigger) { notification.reassigned_merge_request(merge_request, @u_disabled) }
       end
     end
 
@@ -965,33 +916,10 @@ describe NotificationService, services: true do
         should_not_email(@u_lazy_participant)
       end
 
-      context 'participating' do
-        context 'by assignee' do
-          before do
-            merge_request.update_attribute(:assignee, @u_lazy_participant)
-            notification.close_mr(merge_request, @u_disabled)
-          end
-
-          it { should_email(@u_lazy_participant) }
-        end
-
-        context 'by note' do
-          let!(:note) { create(:note_on_issue, noteable: merge_request, project_id: project.id, note: 'anything', author: @u_lazy_participant) }
-
-          before { notification.close_mr(merge_request, @u_disabled) }
-
-          it { should_email(@u_lazy_participant) }
-        end
-
-        context 'by author' do
-          before do
-            merge_request.author = @u_lazy_participant
-            merge_request.save
-            notification.close_mr(merge_request, @u_disabled)
-          end
-
-          it { should_email(@u_lazy_participant) }
-        end
+      it_behaves_like 'participating notifications' do
+        let(:participant) { create(:user, username: 'user-participant') }
+        let(:issuable) { merge_request }
+        let(:notification_trigger) { notification.close_mr(merge_request, @u_disabled) }
       end
     end
 
@@ -1032,33 +960,10 @@ describe NotificationService, services: true do
         should_not_email(@u_watcher)
       end
 
-      context 'participating' do
-        context 'by assignee' do
-          before do
-            merge_request.update_attribute(:assignee, @u_lazy_participant)
-            notification.merge_mr(merge_request, @u_disabled)
-          end
-
-          it { should_email(@u_lazy_participant) }
-        end
-
-        context 'by note' do
-          let!(:note) { create(:note_on_issue, noteable: merge_request, project_id: project.id, note: 'anything', author: @u_lazy_participant) }
-
-          before { notification.merge_mr(merge_request, @u_disabled) }
-
-          it { should_email(@u_lazy_participant) }
-        end
-
-        context 'by author' do
-          before do
-            merge_request.author = @u_lazy_participant
-            merge_request.save
-            notification.merge_mr(merge_request, @u_disabled)
-          end
-
-          it { should_email(@u_lazy_participant) }
-        end
+      it_behaves_like 'participating notifications' do
+        let(:participant) { create(:user, username: 'user-participant') }
+        let(:issuable) { merge_request }
+        let(:notification_trigger) { notification.merge_mr(merge_request, @u_disabled) }
       end
     end
 
@@ -1085,33 +990,10 @@ describe NotificationService, services: true do
         should_not_email(@u_lazy_participant)
       end
 
-      context 'participating' do
-        context 'by assignee' do
-          before do
-            merge_request.update_attribute(:assignee, @u_lazy_participant)
-            notification.reopen_mr(merge_request, @u_disabled)
-          end
-
-          it { should_email(@u_lazy_participant) }
-        end
-
-        context 'by note' do
-          let!(:note) { create(:note_on_issue, noteable: merge_request, project_id: project.id, note: 'anything', author: @u_lazy_participant) }
-
-          before { notification.reopen_mr(merge_request, @u_disabled) }
-
-          it { should_email(@u_lazy_participant) }
-        end
-
-        context 'by author' do
-          before do
-            merge_request.author = @u_lazy_participant
-            merge_request.save
-            notification.reopen_mr(merge_request, @u_disabled)
-          end
-
-          it { should_email(@u_lazy_participant) }
-        end
+      it_behaves_like 'participating notifications' do
+        let(:participant) { create(:user, username: 'user-participant') }
+        let(:issuable) { merge_request }
+        let(:notification_trigger) { notification.reopen_mr(merge_request, @u_disabled) }
       end
     end
 
@@ -1131,33 +1013,10 @@ describe NotificationService, services: true do
         should_not_email(@u_lazy_participant)
       end
 
-      context 'participating' do
-        context 'by assignee' do
-          before do
-            merge_request.update_attribute(:assignee, @u_lazy_participant)
-            notification.resolve_all_discussions(merge_request, @u_disabled)
-          end
-
-          it { should_email(@u_lazy_participant) }
-        end
-
-        context 'by note' do
-          let!(:note) { create(:note_on_issue, noteable: merge_request, project_id: project.id, note: 'anything', author: @u_lazy_participant) }
-
-          before { notification.resolve_all_discussions(merge_request, @u_disabled) }
-
-          it { should_email(@u_lazy_participant) }
-        end
-
-        context 'by author' do
-          before do
-            merge_request.author = @u_lazy_participant
-            merge_request.save
-            notification.resolve_all_discussions(merge_request, @u_disabled)
-          end
-
-          it { should_email(@u_lazy_participant) }
-        end
+      it_behaves_like 'participating notifications' do
+        let(:participant) { create(:user, username: 'user-participant') }
+        let(:issuable) { merge_request }
+        let(:notification_trigger) { notification.resolve_all_discussions(merge_request, @u_disabled) }
       end
     end
   end