Address MR review comments

app/finders/ci/runners_finder.rb

@@ -4,6 +4,9 @@ module Ci
   class RunnersFinder < UnionFinder
     include Gitlab::Allowable
 
+    ALLOWED_SORTS = %w[contacted_asc contacted_desc created_at_asc created_at_desc].freeze
+    DEFAULT_SORT = 'created_date'
+
     def initialize(current_user:, group: nil, params:)
       @params = params
       @group = group
@@ -24,12 +27,7 @@ module Ci
     end
 
     def sort_key
-      case @params[:sort]
-      when 'contacted_asc', 'contacted_desc', 'created_at_asc', 'created_at_desc'
-        @params[:sort]
-      else
-        'created_date'
-      end
+      ALLOWED_SORTS.include?(@params[:sort]) ? @params[:sort] : DEFAULT_SORT
     end
 
     private

spec/finders/ci/runners_finder_spec.rb

@@ -59,27 +59,23 @@ RSpec.describe Ci::RunnersFinder do
           described_class.new(current_user: admin, params: params).execute
         end
 
-        context 'without sort param' do
-          let(:params) { {} }
-
+        shared_examples 'sorts by created_at descending' do
           it 'sorts by created_at descending' do
             is_expected.to eq [runner3, runner2, runner1]
           end
         end
 
-        context 'with sort param equal to created_date' do
-          let(:params) { { sort: 'created_date' } }
+        context 'without sort param' do
+          let(:params) { {} }
 
-          it 'sorts by created_at descending' do
-            is_expected.to eq [runner3, runner2, runner1]
-          end
+          it_behaves_like 'sorts by created_at descending'
         end
 
-        context 'with sort param equal to created_at_desc' do
-          let(:params) { { sort: 'created_at_desc' } }
+        %w(created_date created_at_desc).each do |sort|
+          context "with sort param equal to #{sort}" do
+            let(:params) { { sort: sort } }
 
-          it 'sorts by created_at descending' do
-            is_expected.to eq [runner3, runner2, runner1]
+            it_behaves_like 'sorts by created_at descending'
           end
         end
 
@@ -91,7 +87,6 @@ RSpec.describe Ci::RunnersFinder do
           end
         end
 
-        context 'by contacted_at' do
         context 'with sort param equal to contacted_asc' do
           let(:params) { { sort: 'contacted_asc' } }
 
@@ -108,7 +103,6 @@ RSpec.describe Ci::RunnersFinder do
           end
         end
       end
-      end
 
       context 'non admin user' do
         it 'returns no runners' do