Avoid encoding errors for MergeToRefService

changelogs/unreleased/osw-avoid-encoding-errors-on-merge-to-ref-service.yml

+---
+title: Handle encoding errors for MergeToRefService
+merge_request: 29440
+author:
+type: fixed

lib/gitlab/gitaly_client/operation_service.rb

@@ -107,7 +107,7 @@ module Gitlab
           branch: encode_binary(branch),
           target_ref: encode_binary(target_ref),
           user: Gitlab::Git::User.from_gitlab(user).to_gitaly,
-          message: message
+          message: encode_binary(message)
         )
 
         response = GitalyClient.call(@repository.storage, :operation_service, :user_merge_to_ref, request)

spec/lib/gitlab/gitaly_client/operation_service_spec.rb

@@ -78,6 +78,24 @@ describe Gitlab::GitalyClient::OperationService do
       subject
     end
 
+    describe '#user_merge_to_ref' do
+      let(:branch) { 'my-branch' }
+      let(:source_sha) { 'cfe32cf61b73a0d5e9f13e774abde7ff789b1660' }
+      let(:ref) { 'refs/merge-requests/x/merge' }
+      let(:message) { 'validación' }
+      let(:response) { Gitaly::UserMergeToRefResponse.new(commit_id: 'new-commit-id') }
+
+      subject { client.user_merge_to_ref(user, source_sha, branch, ref, message) }
+
+      it 'sends a user_merge_to_ref message' do
+        expect_any_instance_of(Gitaly::OperationService::Stub)
+          .to receive(:user_merge_to_ref).with(kind_of(Gitaly::UserMergeToRefRequest), kind_of(Hash))
+          .and_return(response)
+
+        subject
+      end
+    end
+
     context "when pre_receive_error is present" do
       let(:response) do
         Gitaly::UserUpdateBranchResponse.new(pre_receive_error: "GitLab: something failed")