Check snippet note event visibility

app/models/event.rb

@@ -148,6 +148,8 @@ class Event < ActiveRecord::Base
     end
   end
 
+  # rubocop:disable Metrics/CyclomaticComplexity
+  # rubocop:disable Metrics/PerceivedComplexity
   def visible_to_user?(user = nil)
     if push? || commit_note?
       Ability.allowed?(user, :download_code, project)
@@ -159,12 +161,18 @@ class Event < ActiveRecord::Base
       Ability.allowed?(user, :read_issue, note? ? note_target : target)
     elsif merge_request? || merge_request_note?
       Ability.allowed?(user, :read_merge_request, note? ? note_target : target)
+    elsif personal_snippet_note?
+      Ability.allowed?(user, :read_personal_snippet, note_target)
+    elsif project_snippet_note?
+      Ability.allowed?(user, :read_project_snippet, note_target)
     elsif milestone?
       Ability.allowed?(user, :read_milestone, project)
     else
       false # No other event types are visible
     end
   end
+  # rubocop:enable Metrics/PerceivedComplexity
+  # rubocop:enable Metrics/CyclomaticComplexity
 
   def project_name
     if project
@@ -306,6 +314,10 @@ class Event < ActiveRecord::Base
     note? && target && target.for_snippet?
   end
 
+  def personal_snippet_note?
+    note? && target && target.for_personal_snippet?
+  end
+
   def note_target
     target.noteable
   end

spec/models/event_spec.rb

@@ -148,9 +148,13 @@ describe Event do
     let(:admin) { create(:admin) }
     let(:issue) { create(:issue, project: project, author: author, assignees: [assignee]) }
     let(:confidential_issue) { create(:issue, :confidential, project: project, author: author, assignees: [assignee]) }
+    let(:project_snippet) { create(:project_snippet, :public, project: project, author: author) }
+    let(:personal_snippet) { create(:personal_snippet, :public, author: author) }
     let(:note_on_commit) { create(:note_on_commit, project: project) }
     let(:note_on_issue) { create(:note_on_issue, noteable: issue, project: project) }
     let(:note_on_confidential_issue) { create(:note_on_issue, noteable: confidential_issue, project: project) }
+    let(:note_on_project_snippet) { create(:note_on_project_snippet, author: author, noteable: project_snippet, project: project) }
+    let(:note_on_personal_snippet) { create(:note_on_personal_snippet, author: author, noteable: personal_snippet, project: nil) }
     let(:milestone_on_project) { create(:milestone, project: project) }
     let(:event) { described_class.new(project: project, target: target, author_id: author.id) }
 
@@ -305,6 +309,89 @@ describe Event do
         end
       end
     end
+
+    context 'project snippet note event' do
+      let(:target) { note_on_project_snippet }
+
+      it do
+        expect(event.visible_to_user?(nil)).to be_truthy
+        expect(event.visible_to_user?(non_member)).to be_truthy
+        expect(event.visible_to_user?(author)).to be_truthy
+        expect(event.visible_to_user?(member)).to be_truthy
+        expect(event.visible_to_user?(guest)).to be_truthy
+        expect(event.visible_to_user?(admin)).to be_truthy
+      end
+
+      context 'on public project with private snippets' do
+        let(:project) { create(:project, :public, :snippets_private) }
+
+        it do
+          expect(event.visible_to_user?(nil)).to be_falsy
+          expect(event.visible_to_user?(non_member)).to be_falsy
+
+          # Normally, we'd expect the author of a comment to be able to view it.
+          # However, this doesn't seem to be the case for comments on snippets.
+          expect(event.visible_to_user?(author)).to be_falsy
+
+          expect(event.visible_to_user?(member)).to be_truthy
+          expect(event.visible_to_user?(guest)).to be_truthy
+          expect(event.visible_to_user?(admin)).to be_truthy
+        end
+      end
+
+      context 'on private project' do
+        let(:project) { create(:project, :private) }
+
+        it do
+          expect(event.visible_to_user?(nil)).to be_falsy
+          expect(event.visible_to_user?(non_member)).to be_falsy
+
+          # Normally, we'd expect the author of a comment to be able to view it.
+          # However, this doesn't seem to be the case for comments on snippets.
+          expect(event.visible_to_user?(author)).to be_falsy
+
+          expect(event.visible_to_user?(member)).to be_truthy
+          expect(event.visible_to_user?(guest)).to be_truthy
+          expect(event.visible_to_user?(admin)).to be_truthy
+        end
+      end
+    end
+
+    context 'personal snippet note event' do
+      let(:target) { note_on_personal_snippet }
+
+      it do
+        expect(event.visible_to_user?(nil)).to be_truthy
+        expect(event.visible_to_user?(non_member)).to be_truthy
+        expect(event.visible_to_user?(author)).to be_truthy
+        expect(event.visible_to_user?(admin)).to be_truthy
+      end
+
+      context 'on internal snippet' do
+        let(:personal_snippet) { create(:personal_snippet, :internal, author: author) }
+
+        it do
+          expect(event.visible_to_user?(nil)).to be_falsy
+          expect(event.visible_to_user?(non_member)).to be_truthy
+          expect(event.visible_to_user?(author)).to be_truthy
+          expect(event.visible_to_user?(admin)).to be_truthy
+        end
+      end
+
+      context 'on private snippet' do
+        let(:personal_snippet) { create(:personal_snippet, :private, author: author) }
+
+        it do
+          expect(event.visible_to_user?(nil)).to be_falsy
+          expect(event.visible_to_user?(non_member)).to be_falsy
+          expect(event.visible_to_user?(author)).to be_truthy
+
+          # It is very unexpected that a private personal snippet is not visible
+          # to an instance administrator. This should be fixed in the future.
+          expect(event.visible_to_user?(admin)).to be_falsy
+        end
+      end
+    end
   end
 
   describe '.limit_recent' do