Suggestions: use template from target project instead of source project

Suggestions defined in MR would show values from target project when
previewing the commit message. However, once the commit was actually
created, it used values from source project instead. This means that
forks would ignore target project settings. The difference in preview
and result would also confuse users.
This MR changes it, so that suggestions always use target project when
generating the message, both for template definition and project name
and path variables.

Changelog: fixed

app/models/suggestion.rb

@@ -16,10 +16,14 @@ class Suggestion < ApplicationRecord
     note.latest_diff_file
   end
 
-  def project
+  def source_project
     noteable.source_project
   end
 
+  def target_project
+    noteable.target_project
+  end
+
   def branch
     noteable.source_branch
   end

app/policies/suggestion_policy.rb

 # frozen_string_literal: true
 
 class SuggestionPolicy < BasePolicy
-  delegate { @subject.project }
+  delegate { @subject.source_project }
 
   condition(:can_push_to_branch) do
-    Gitlab::UserAccess.new(@user, container: @subject.project).can_push_to_branch?(@subject.branch)
+    Gitlab::UserAccess.new(@user, container: @subject.source_project).can_push_to_branch?(@subject.branch)
   end
 
   rule { can_push_to_branch }.enable :apply_suggestion

app/services/suggestions/apply_service.rb

@@ -54,7 +54,7 @@ module Suggestions
         author_email: author&.email
       }
 
-      ::Files::MultiService.new(suggestion_set.project, current_user, params)
+      ::Files::MultiService.new(suggestion_set.source_project, current_user, params)
     end
 
     def commit_message

doc/user/project/merge_requests/reviews/suggestions.md

@@ -108,6 +108,8 @@ For example, to customize the commit message to output
 **Addresses user_1's review**, set the custom text to
 `Addresses %{username}'s review`.
 
+For merge requests created from forks, GitLab uses the template defined in target project.
+
 NOTE:
 Custom commit messages for each applied suggestion is
 introduced by [#25381](https://gitlab.com/gitlab-org/gitlab/-/issues/25381).

lib/gitlab/suggestions/commit_message.rb

@@ -13,7 +13,7 @@ module Gitlab
       end
 
       def message
-        project = suggestion_set.project
+        project = suggestion_set.target_project
         user_defined_message = @custom_message.presence || project.suggestion_commit_message.presence
         message = user_defined_message || DEFAULT_SUGGESTION_COMMIT_MESSAGE
 
@@ -37,8 +37,8 @@ module Gitlab
         'branch_name' => ->(user, suggestion_set) { suggestion_set.branch },
         'files_count' => ->(user, suggestion_set) { suggestion_set.file_paths.length },
         'file_paths' => ->(user, suggestion_set) { format_paths(suggestion_set.file_paths) },
-        'project_name' => ->(user, suggestion_set) { suggestion_set.project.name },
-        'project_path' => ->(user, suggestion_set) { suggestion_set.project.path },
+        'project_name' => ->(user, suggestion_set) { suggestion_set.target_project.name },
+        'project_path' => ->(user, suggestion_set) { suggestion_set.target_project.path },
         'user_full_name' => ->(user, suggestion_set) { user.name },
         'username' => ->(user, suggestion_set) { user.username },
         'suggestions_count' => ->(user, suggestion_set) { suggestion_set.suggestions.size }

lib/gitlab/suggestions/suggestion_set.rb

@@ -9,8 +9,12 @@ module Gitlab
         @suggestions = suggestions
       end
 
-      def project
-        first_suggestion.project
+      def source_project
+        first_suggestion.source_project
+      end
+
+      def target_project
+        first_suggestion.target_project
       end
 
       def branch

spec/lib/gitlab/suggestions/commit_message_spec.rb

@@ -3,7 +3,10 @@
 require 'spec_helper'
 
 RSpec.describe Gitlab::Suggestions::CommitMessage do
-  def create_suggestion(file_path, new_line, to_content)
+  include ProjectForksHelper
+  using RSpec::Parameterized::TableSyntax
+
+  def create_suggestion(merge_request, file_path, new_line, to_content)
     position = Gitlab::Diff::Position.new(old_path: file_path,
                                           new_path: file_path,
                                           old_line: nil,
@@ -29,25 +32,45 @@ RSpec.describe Gitlab::Suggestions::CommitMessage do
     create(:project, :repository, path: 'project-1', name: 'Project_1')
   end
 
-  let_it_be(:merge_request) do
+  let_it_be(:forked_project) { fork_project(project, nil, repository: true) }
+
+  let_it_be(:merge_request_same_project) do
     create(:merge_request, source_project: project, target_project: project)
   end
 
-  let_it_be(:suggestion_set) do
-    suggestion1 = create_suggestion('files/ruby/popen.rb', 9, '*** SUGGESTION 1 ***')
-    suggestion2 = create_suggestion('files/ruby/popen.rb', 13, '*** SUGGESTION 2 ***')
-    suggestion3 = create_suggestion('files/ruby/regex.rb', 22, '*** SUGGESTION 3 ***')
+  let_it_be(:merge_request_from_fork) do
+    create(:merge_request, source_project: forked_project, target_project: project)
+  end
+
+  let_it_be(:suggestion_set_same_project) do
+    suggestion1 = create_suggestion(merge_request_same_project, 'files/ruby/popen.rb', 9, '*** SUGGESTION 1 ***')
+    suggestion2 = create_suggestion(merge_request_same_project, 'files/ruby/popen.rb', 13, '*** SUGGESTION 2 ***')
+    suggestion3 = create_suggestion(merge_request_same_project, 'files/ruby/regex.rb', 22, '*** SUGGESTION 3 ***')
+
+    Gitlab::Suggestions::SuggestionSet.new([suggestion1, suggestion2, suggestion3])
+  end
+
+  let_it_be(:suggestion_set_forked_project) do
+    suggestion1 = create_suggestion(merge_request_from_fork, 'files/ruby/popen.rb', 9, '*** SUGGESTION 1 ***')
+    suggestion2 = create_suggestion(merge_request_from_fork, 'files/ruby/popen.rb', 13, '*** SUGGESTION 2 ***')
+    suggestion3 = create_suggestion(merge_request_from_fork, 'files/ruby/regex.rb', 22, '*** SUGGESTION 3 ***')
 
     Gitlab::Suggestions::SuggestionSet.new([suggestion1, suggestion2, suggestion3])
   end
 
   describe '#message' do
+    where(:suggestion_set) { [ref(:suggestion_set_same_project), ref(:suggestion_set_forked_project)] }
+
+    with_them do
       before do
         # Updating the suggestion_commit_message on a project shared across specs
         # avoids recreating the repository for each spec.
         project.update!(suggestion_commit_message: message)
+        forked_project.update!(suggestion_commit_message: fork_message)
       end
 
+      let(:fork_message) { nil }
+
       context 'when a custom commit message is not specified' do
         let(:expected_message) { 'Apply 3 suggestion(s) to 2 file(s)' }
 
@@ -70,6 +93,17 @@ RSpec.describe Gitlab::Suggestions::CommitMessage do
                     .message).to eq(expected_message)
           end
         end
+
+        context 'when a custom commit message is specified for forked project' do
+          let(:message) { nil }
+          let(:fork_message) { "I'm a sad message that will not be used :(" }
+
+          it 'uses the default commit message' do
+            expect(described_class
+                     .new(user, suggestion_set)
+                     .message).to eq(expected_message)
+          end
+        end
       end
 
       context 'when a custom commit message is specified' do
@@ -93,6 +127,17 @@ RSpec.describe Gitlab::Suggestions::CommitMessage do
                   .new(user, suggestion_set)
                   .message).to eq('*** master 2 files/ruby/popen.rb, files/ruby/regex.rb Project_1 project-1 Test User test.user 3 ***')
         end
+
+        context 'when a custom commit message is specified for forked project' do
+          let(:fork_message) { "I'm a sad message that will not be used :(" }
+
+          it 'uses the target project commit message' do
+            expect(Gitlab::Suggestions::CommitMessage
+                    .new(user, suggestion_set)
+                    .message).to eq('*** master 2 files/ruby/popen.rb, files/ruby/regex.rb Project_1 project-1 Test User test.user 3 ***')
+          end
+        end
+      end
     end
   end
 end

spec/lib/gitlab/suggestions/suggestion_set_spec.rb

@@ -3,6 +3,9 @@
 require 'spec_helper'
 
 RSpec.describe Gitlab::Suggestions::SuggestionSet do
+  include ProjectForksHelper
+  using RSpec::Parameterized::TableSyntax
+
   def create_suggestion(file_path, new_line, to_content)
     position = Gitlab::Diff::Position.new(old_path: file_path,
                                           new_path: file_path,
@@ -24,30 +27,42 @@ RSpec.describe Gitlab::Suggestions::SuggestionSet do
   let_it_be(:user) { create(:user) }
 
   let_it_be(:project) { create(:project, :repository) }
+  let_it_be(:forked_project) { fork_project(project, nil, repository: true) }
 
-  let_it_be(:merge_request) do
+  let_it_be(:merge_request_same_project) do
     create(:merge_request, source_project: project, target_project: project)
   end
 
-  let_it_be(:suggestion) { create(:suggestion)}
+  let_it_be(:merge_request_from_fork) do
+    create(:merge_request, source_project: forked_project, target_project: project)
+  end
+
+  where(:merge_request) { [ref(:merge_request_same_project), ref(:merge_request_from_fork)] }
+  with_them do
+    let(:note) { create(:diff_note_on_merge_request, project: project, noteable: merge_request) }
+    let(:suggestion) { create(:suggestion, note: note) }
 
-  let_it_be(:suggestion2) do
+    let(:suggestion2) do
       create_suggestion('files/ruby/popen.rb', 13, "*** SUGGESTION 2 ***")
     end
 
-  let_it_be(:suggestion3) do
+    let(:suggestion3) do
       create_suggestion('files/ruby/regex.rb', 22, "*** SUGGESTION 3 ***")
     end
 
-  let_it_be(:unappliable_suggestion) { create(:suggestion, :unappliable) }
+    let(:unappliable_suggestion) { create(:suggestion, :unappliable) }
 
     let(:suggestion_set) { described_class.new([suggestion]) }
 
-  describe '#project' do
-    it 'returns the project associated with the suggestions' do
-      expected_project = suggestion.project
+    describe '#source_project' do
+      it 'returns the source project associated with the suggestions' do
+        expect(suggestion_set.source_project).to be(merge_request.source_project)
+      end
+    end
 
-      expect(suggestion_set.project).to be(expected_project)
+    describe '#target_project' do
+      it 'returns the target project associated with the suggestions' do
+        expect(suggestion_set.target_project).to be(project)
       end
     end
 
@@ -106,4 +121,5 @@ RSpec.describe Gitlab::Suggestions::SuggestionSet do
         expect(actual_paths.sort).to eq(expected_paths)
       end
     end
+  end
 end