Merge branch '21247-mergerequestscontroller-conflicts-may-fail-with-iso-8859-data' into 'master'

Handle non-UTF-8 conflicts gracefully

## What does this MR do?

If a conflict file isn't in a UTF-8-compatible encoding, we can't resolve it in the UI.

## What are the relevant issue numbers?

Closes #21247. 

See merge request !5961

1 files changed, 5 insertions, 0 deletions

diff --git a/spec/lib/gitlab/conflict/parser_spec.rb b/spec/lib/gitlab/conflict/parser_spec.rb
index 65a828accde..a1d2ca1e272 100644
--- a/spec/lib/gitlab/conflict/parser_spec.rb
+++ b/spec/lib/gitlab/conflict/parser_spec.rb
@@ -183,6 +183,11 @@ CONFLICT
         expect { parse_text('a' * 102401) }.
           to raise_error(Gitlab::Conflict::Parser::UnmergeableFile)
       end
+
+      it 'raises UnsupportedEncoding when the file contains non-UTF-8 characters' do
+        expect { parse_text("a\xC4\xFC".force_encoding(Encoding::ASCII_8BIT)) }.
+          to raise_error(Gitlab::Conflict::Parser::UnsupportedEncoding)
+      end
     end
   end
 end