Notify conflict only for opened/locked merge requests

app/models/merge_request.rb

@@ -129,9 +129,7 @@ class MergeRequest < ActiveRecord::Base
 
     after_transition unchecked: :cannot_be_merged do |merge_request, transition|
       begin
-        # Merge request can become unmergeable due to many reasons.
-        # We only notify if it is due to conflict.
-        unless merge_request.project.repository.can_be_merged?(merge_request.diff_head_sha, merge_request.target_branch)
+        if merge_request.notify_conflict?
           NotificationService.new.merge_request_unmergeable(merge_request)
           TodoService.new.merge_request_became_unmergeable(merge_request)
         end
@@ -708,6 +706,10 @@ class MergeRequest < ActiveRecord::Base
     should_remove_source_branch? || force_remove_source_branch?
   end
 
+  def notify_conflict?
+    (opened? || locked?) && !project.repository.can_be_merged?(diff_head_sha, target_branch)
+  end
+
   def related_notes
     # Fetch comments only from last 100 commits
     commits_for_notes_limit = 100

changelogs/unreleased/6598-notify-only-open-unmergeable-mr.yml

+---
+title: Notify conflict for only open merge request
+merge_request: 20125
+author:
+type: fixed

doc/workflow/notifications.md

@@ -111,7 +111,7 @@ by yourself (except when an issue is due). You will only receive automatic
 notifications when somebody else comments or adds changes to the ones that
 you've created or mentions you.
 
-If a merge request becomes unmergeable, its author will be notified about the cause.
+If an open merge request becomes unmergeable due to conflict, its author will be notified about the cause.
 If a user has also set the merge request to automatically merge once pipeline succeeds,
 then that user will also be notified.
 

doc/workflow/todos.md

@@ -31,7 +31,7 @@ A Todo appears in your Todos dashboard when:
 - you are `@mentioned` in a comment on a commit,
 - a job in the CI pipeline running for your merge request failed, but this
   job is not allowed to fail.
-- a merge request becomes unmergeable, and you are either:
+- an open merge request becomes unmergeable due to conflict, and you are either:
   - the author, or
   - have set it to automatically merge once pipeline succeeds.
 

spec/models/merge_request_spec.rb

@@ -2134,8 +2134,7 @@ describe MergeRequest do
     describe 'transition to cannot_be_merged' do
       let(:notification_service) { double(:notification_service) }
       let(:todo_service) { double(:todo_service) }
-
-      subject { create(:merge_request, merge_status: :unchecked) }
+      subject { create(:merge_request, state, merge_status: :unchecked) }
 
       before do
         allow(NotificationService).to receive(:new).and_return(notification_service)
@@ -2144,6 +2143,10 @@ describe MergeRequest do
         allow(subject.project.repository).to receive(:can_be_merged?).and_return(false)
       end
 
+      [:opened, :locked].each do |state|
+        context state do
+          let(:state) { state }
+
           it 'notifies conflict, but does not notify again if rechecking still results in cannot_be_merged' do
             expect(notification_service).to receive(:merge_request_unmergeable).with(subject).once
             expect(todo_service).to receive(:merge_request_became_unmergeable).with(subject).once
@@ -2173,6 +2176,21 @@ describe MergeRequest do
             subject.mark_as_unmergeable
           end
         end
+      end
+
+      [:closed, :merged].each do |state|
+        let(:state) { state }
+
+        context state do
+          it 'does not notify' do
+            expect(notification_service).not_to receive(:merge_request_unmergeable)
+            expect(todo_service).not_to receive(:merge_request_became_unmergeable)
+
+            subject.mark_as_unmergeable
+          end
+        end
+      end
+    end
 
     describe 'check_state?' do
       it 'indicates whether MR is still checking for mergeability' do