Use modified paths inside AuthorityAnalyzer

ee/lib/gitlab/authority_analyzer.rb

@@ -3,6 +3,7 @@
 module Gitlab
   class AuthorityAnalyzer
     COMMITS_TO_CONSIDER = 25
+    FILES_TO_CONSIDER = 100
 
     def initialize(merge_request, skip_user)
       @merge_request = merge_request
@@ -30,20 +31,7 @@ module Gitlab
     end
 
     def list_of_involved_files
-      diffable = [@merge_request.compare, @merge_request.merge_request_diff].compact
-      return [] if diffable.empty?
-
-      compare_diffs = diffable.first.raw_diffs
-
-      return [] unless compare_diffs.present?
-
-      compare_diffs.map do |diff|
-        if diff.deleted_file || diff.renamed_file
-          diff.old_path
-        else
-          diff.new_path
-        end
-      end
+      @merge_request.modified_paths.first(FILES_TO_CONSIDER)
     end
   end
 end

ee/spec/lib/gitlab/authority_analyzer_spec.rb

@@ -9,7 +9,7 @@ describe Gitlab::AuthorityAnalyzer do
     let(:user_a) { create(:user) }
     let(:user_b) { create(:user) }
     let(:merge_request) { create(:merge_request, target_project: project, source_project: project) }
-    let(:files) { [double(:file, deleted_file: true, old_path: 'foo')] }
+    let(:files) { %w(so many files) }
 
     let(:commits) do
       [
@@ -23,12 +23,14 @@ describe Gitlab::AuthorityAnalyzer do
 
     let(:approvers) { described_class.new(merge_request, author).calculate }
 
-    before do
-      merge_request.compare = double(:compare, raw_diffs: files)
-      allow(merge_request.target_project.repository).to receive(:commits).and_return(commits)
-    end
-
     it 'returns contributors in order, without skip_user' do
+      stub_const('Gitlab::AuthorityAnalyzer::FILES_TO_CONSIDER', 1)
+
+      expect(merge_request).to receive(:modified_paths).and_return(files)
+      expect(merge_request.target_project.repository).to receive(:commits)
+        .with(merge_request.target_branch, path: ['so'], limit: Gitlab::AuthorityAnalyzer::COMMITS_TO_CONSIDER)
+        .and_return(commits)
+
       expect(approvers).to contain_exactly(user_a, user_b)
     end
   end