1 files changed, 37 insertions, 1 deletions
diff --git a/spec/lib/gitlab/utils_spec.rb b/spec/lib/gitlab/utils_spec.rb
index 3a2430d1f2d..7a0d40ff0d2 100644
--- a/spec/lib/gitlab/utils_spec.rb
+++ b/spec/lib/gitlab/utils_spec.rb
@@ -2,7 +2,7 @@
 
 require 'spec_helper'
 
-describe Gitlab::Utils do
+RSpec.describe Gitlab::Utils do
   delegate :to_boolean, :boolean_to_yes_no, :slugify, :random_string, :which,
            :ensure_array_from_string, :to_exclusive_sentence, :bytes_to_megabytes,
            :append_path, :check_path_traversal!, :ms_to_round_sec, to: :described_class
@@ -358,4 +358,40 @@ describe Gitlab::Utils do
       })
     end
   end
+
+  describe '.stable_sort_by' do
+    subject(:sorted_list) { described_class.stable_sort_by(list) { |obj| obj[:priority] } }
+
+    context 'when items have the same priority' do
+      let(:list) do
+        [
+          { name: 'obj 1', priority: 1 },
+          { name: 'obj 2', priority: 1 },
+          { name: 'obj 3', priority: 1 }
+        ]
+      end
+
+      it 'does not change order in cases of ties' do
+        expect(sorted_list).to eq(list)
+      end
+    end
+
+    context 'when items have different priorities' do
+      let(:list) do
+        [
+          { name: 'obj 1', priority: 2 },
+          { name: 'obj 2', priority: 1 },
+          { name: 'obj 3', priority: 3 }
+        ]
+      end
+
+      it 'sorts items like the regular sort_by' do
+        expect(sorted_list).to eq([
+          { name: 'obj 2', priority: 1 },
+          { name: 'obj 1', priority: 2 },
+          { name: 'obj 3', priority: 3 }
+        ])
+      end
+    end
+  end
 end