FIX: EmberCli cache clearance issue in production (#24343)

spec/lib/ember_cli_spec.rb

@@ -6,4 +6,45 @@ describe EmberCli do
       expect(EmberCli.ember_version).to match(/\A\d+\.\d+/)
     end
   end
+
+  describe "cache" do
+    after { EmberCli.clear_cache! }
+
+    def simulate_request_cache_clearance
+      # this method is defined by ActiveSupport::CurrentAttributes
+      # and is called before/after every web request
+      EmberCli.reset
+    end
+
+    context "in development" do
+      before { Rails.env.stubs(:development?).returns(true) }
+
+      it "cache works, and is cleared before/after each web request" do
+        EmberCli.cache[:foo] = "bar"
+        expect(EmberCli.cache[:foo]).to eq("bar")
+
+        simulate_request_cache_clearance
+
+        expect(EmberCli.cache[:foo]).to eq(nil)
+      end
+    end
+
+    context "in production" do
+      before { Rails.env.stubs(:development?).returns(false) }
+
+      it "cache works, and can be cleared" do
+        EmberCli.cache[:foo] = "bar"
+        expect(EmberCli.cache[:foo]).to eq("bar")
+
+        simulate_request_cache_clearance
+
+        # In production, persists across requests
+        expect(EmberCli.cache[:foo]).to eq("bar")
+
+        # But still can be manually cleared
+        EmberCli.clear_cache!
+        expect(EmberCli.cache[:foo]).to eq(nil)
+      end
+    end
+  end
 end