Fix for #222780, batch suggestions now accomodate suggestions that can add or remove lines.

lib/gitlab/suggestions/file_suggestion.rb

@@ -51,17 +51,24 @@ module Gitlab
         @current_content ||= blob.nil? ? [''] : blob_data_lines
       end
 
+      def sorted_suggestions
+        @sorted_suggestions ||= suggestions.sort_by(&:from_line_index)
+      end
+
       def _new_content
+        offset = 0
+
         current_content.tap do |content|
-          suggestions.each do |suggestion|
-            range = line_range(suggestion)
+          sorted_suggestions.each do |suggestion|
+            range = line_range(suggestion, offset)
             content[range] = suggestion.to_content
+            offset = suggestion.to_line_index - suggestion.from_line_index
           end
         end.join
       end
 
-      def line_range(suggestion)
-        suggestion.from_line_index..suggestion.to_line_index
+      def line_range(suggestion, offset = 0)
+        (suggestion.from_line_index - offset)..suggestion.to_line_index
       end
 
       def for_different_file?(suggestion)

spec/services/suggestions/apply_service_spec.rb

@@ -123,11 +123,25 @@ describe Suggestions::ApplyService do
 
   let(:position) { build_position }
 
+  let(:position2) do
+    Gitlab::Diff::Position.new(old_path: "files/ruby/popen.rb",
+                               new_path: "files/ruby/popen.rb",
+                               old_line: nil,
+                               new_line: 15,
+                               diff_refs: merge_request
+                                              .diff_refs)
+  end
+
   let(:diff_note) do
     create(:diff_note_on_merge_request, noteable: merge_request,
            position: position, project: project)
   end
 
+  let(:diff_note2) do
+    create(:diff_note_on_merge_request, noteable: merge_request,
+           position: position2, project: project)
+  end
+
   let(:suggestion) do
     create(:suggestion, :content_from_repo, note: diff_note,
            to_content: "      raise RuntimeError, 'Explosion'\n      # explosion?\n")
@@ -387,14 +401,8 @@ describe Suggestions::ApplyService do
             # multi
             # line
 
-                vars = {
-                  "PWD" => path
-                }
-
-                options = {
-                  chdir: path
-                }
-
+            # multi_1
+            # line_2
                 unless File.directory?(path)
                   FileUtils.mkdir_p(path)
                 end
@@ -427,7 +435,14 @@ describe Suggestions::ApplyService do
                  to_content: "# multi\n# line\n")
         end
 
-        let(:suggestions) { [suggestion] }
+        let(:suggestion2) do
+          create(:suggestion, :content_from_repo, note: diff_note2,
+                 lines_above: 1,
+                 lines_below: 1,
+                 to_content: "# multi_1\n# line_2\n")
+        end
+
+        let(:suggestions) { [suggestion, suggestion2] }
 
         it_behaves_like 'successfully creates commit and updates suggestions'
       end