Test etag cache key changing value

app/models/environment.rb

@@ -202,11 +202,16 @@ class Environment < ActiveRecord::Base
 
   def expire_etag_cache
     Gitlab::EtagCaching::Store.new.tap do |store|
-      store.touch(Gitlab::Routing.url_helpers
-        .namespace_project_environments_path(project.namespace, project))
+      store.touch(etag_cache_key)
     end
   end
 
+  def etag_cache_key
+    Gitlab::Routing.url_helpers.namespace_project_environments_path(
+      project.namespace,
+      project)
+  end
+
   private
 
   # Slugifying a name may remove the uniqueness guarantee afforded by it being

spec/models/environment_spec.rb

@@ -42,6 +42,18 @@ describe Environment, models: true do
     end
   end
 
+  describe '#expire_etag_cache' do
+    let(:store) { Gitlab::EtagCaching::Store.new }
+
+    it 'changes the cached value' do
+      old_value = store.get(environment.etag_cache_key)
+
+      environment.stop
+
+      expect(store.get(environment.etag_cache_key)).not_to eq(old_value)
+    end
+  end
+
   describe '#nullify_external_url' do
     it 'replaces a blank url with nil' do
       env = build(:environment, external_url: "")