Merge branch...

Merge branch '32079-misleading-suggestion-is-created-when-made-at-the-last-line-of-a-file-with-no-newline-at-end' into 'master'

Resolve "Misleading suggestion is created when made at the last line of a file with "\ No newline at end of file""

Closes #32079

See merge request gitlab-org/gitlab!22732

changelogs/unreleased/32079-misleading-suggestion-is-created-when-made-at-the-last-line-of-a-fi.yml

+---
+title: Fixes a new line issue with suggestions in the last line of a file
+merge_request: 22732
+author:
+type: fixed

lib/gitlab/diff/suggestion_diff.rb

@@ -18,7 +18,7 @@ module Gitlab
       private
 
       def raw_diff
-        "#{diff_header}\n#{from_content_as_diff}#{to_content_as_diff}"
+        "#{diff_header}\n#{from_content_as_diff}\n#{to_content_as_diff}"
       end
 
       def diff_header
@@ -26,7 +26,7 @@ module Gitlab
       end
 
       def from_content_as_diff
-        from_content.lines.map { |line| line.prepend('-') }.join
+        from_content.lines.map { |line| line.prepend('-') }.join.delete_suffix("\n")
       end
 
       def to_content_as_diff

spec/lib/gitlab/diff/suggestion_diff_spec.rb

@@ -51,5 +51,20 @@ describe Gitlab::Diff::SuggestionDiff do
         expect(diff_lines[index].to_hash).to include(expected_line)
       end
     end
+
+    describe 'when the suggestion is for the last line of a file' do
+      it 'returns a correct value if there is no newline at the end of the file' do
+        from_content = "One line test"
+        to_content = "Successful test!"
+        suggestion = instance_double(Suggestion, from_line: 1,
+                                                 from_content: from_content,
+                                                 to_content: to_content)
+
+        diff_lines = described_class.new(suggestion).diff_lines
+
+        expect(diff_lines.first.text).to eq("-One line test")
+        expect(diff_lines.last.text).to eq("+Successful test!")
+      end
+    end
   end
 end