Fix display of push events for removed refs

This changes the style of push events that remove tags or branches so
they don't display the commit details. This prevents displaying commit
details such as:

    000000 . --broken encoding

Instead we now simply display the header such as:

    Administrator deleted branch example-branch

This is displayed in the same style as events for newly created
branches/tags.

This commit also ensures that if no commit message is present we simply
don't display anything, instead of "--broken encoding".

Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/36685
Fixes https://gitlab.com/gitlab-org/gitlab-ce/issues/36722

app/helpers/events_helper.rb

@@ -181,6 +181,7 @@ module EventsHelper
   end
 
   def event_commit_title(message)
+    message ||= ''
     (message.split("\n").first || "").truncate(70)
   rescue
     "--broken encoding"

app/models/event.rb

@@ -406,7 +406,7 @@ class Event < ActiveRecord::Base
 
   def body?
     if push?
-      push_with_commits? || rm_ref?
+      push_with_commits?
     elsif note?
       true
     else

app/views/events/_event_push.atom.haml

@@ -5,6 +5,7 @@
     %i
       at
       = event.created_at.to_s(:short)
+  - unless event.rm_ref?
     %blockquote= markdown(escape_once(event.commit_title), pipeline: :atom, project: event.project, author: event.author)
     - if event.commits_count > 1
       %p

app/views/events/event/_push.html.haml

@@ -41,7 +41,3 @@
         %li.commits-stat
           = link_to create_mr_path(project.default_branch, event.ref_name, project) do
             Create Merge Request
-- elsif event.rm_ref?
-  .event-body
-    %ul.well-list.event_commits
-      = render "events/commit", project: project, event: event

changelogs/unreleased/fix-push-events-branch-removals.yml

+---
+title: Fix display of push events for removed refs
+merge_request:
+author:
+type: fixed

spec/helpers/events_helper_spec.rb

@@ -106,5 +106,9 @@ describe EventsHelper do
     it "handles empty strings" do
       expect(helper.event_commit_title("")).to eq("")
     end
+
+    it 'handles nil values' do
+      expect(helper.event_commit_title(nil)).to eq('')
+    end
   end
 end

spec/models/event_spec.rb

@@ -304,6 +304,50 @@ describe Event do
     end
   end
 
+  describe '#body?' do
+    let(:push_event) do
+      event = build(:push_event)
+
+      allow(event).to receive(:push?).and_return(true)
+
+      event
+    end
+
+    it 'returns true for a push event with commits' do
+      allow(push_event).to receive(:push_with_commits?).and_return(true)
+
+      expect(push_event).to be_body
+    end
+
+    it 'returns false for a push event without a valid commit range' do
+      allow(push_event).to receive(:push_with_commits?).and_return(false)
+
+      expect(push_event).not_to be_body
+    end
+
+    it 'returns true for a Note event' do
+      event = build(:event)
+
+      allow(event).to receive(:note?).and_return(true)
+
+      expect(event).to be_body
+    end
+
+    it 'returns true if the target responds to #title' do
+      event = build(:event)
+
+      allow(event).to receive(:target).and_return(double(:target, title: 'foo'))
+
+      expect(event).to be_body
+    end
+
+    it 'returns false for a regular event without a target' do
+      event = build(:event)
+
+      expect(event).not_to be_body
+    end
+  end
+
   def create_push_event(project, user)
     event = create(:push_event, project: project, author: user)