Add test for #cast_value_from_cache

spec/models/concerns/redis_cacheable_spec.rb

@@ -83,4 +83,40 @@ describe RedisCacheable do
       expect(instance.name).to eq('new_value')
     end
   end
+
+  describe '#cast_value_from_cache' do
+    let(:instance) { Ci::Runner.new }
+
+    subject { instance.__send__(:cast_value_from_cache, attribute, value) }
+
+    shared_context 'runner contacted_at context' do
+      let(:attribute) { :contacted_at }
+      let(:value) { '2018-05-07 13:53:08 UTC' }
+    end
+
+    context 'on rails5' do
+      include_context 'runner contacted_at context'
+
+      before do
+        allow(Gitlab).to receive(:rails5?).and_return(true)
+      end
+
+      it 'converts cache string to appropriate type' do
+        pending 'Migration to rails5'
+        expect(subject).to be_an_instance_of(ActiveSupport::TimeWithZone)
+      end
+    end
+
+    context 'not on rails5' do
+      include_context 'runner contacted_at context'
+
+      before do
+        allow(Gitlab).to receive(:rails5?).and_return(false)
+      end
+
+      it 'converts cache string to appropriate type' do
+        expect(subject).to be_an_instance_of(ActiveSupport::TimeWithZone)
+      end
+    end
+  end
 end