add spec to test dependencies sorting for cache_key

Author: razumau

spec/presenter_spec.rb

@@ -226,6 +226,29 @@ class SubNestedPresenter < Curly::Presenter
       expect(cache_key).to eq "Foo::BarPresenter/42/Foo::BumPresenter/1337"
     end
 
+    it "includes the cache keys of all presenters in the dependency list" do
+      presenter = Class.new(Curly::Presenter) do
+        version 42
+        depends_on 'foo/bum'
+        depends_on 'foo/aum'
+      end
+
+      dependency = Class.new(Curly::Presenter) do
+        version 1337
+      end
+
+      dependency_2 = Class.new(Curly::Presenter) do
+        version 1338
+      end
+
+      stub_const("Foo::BarPresenter", presenter)
+      stub_const("Foo::BumPresenter", dependency)
+      stub_const("Foo::AumPresenter", dependency_2)
+
+      cache_key = Foo::BarPresenter.cache_key
+      expect(cache_key).to eq "Foo::BarPresenter/42/Foo::AumPresenter/1338/Foo::BumPresenter/1337"
+    end
+
     it "uses the view path of a dependency if there is no presenter for it" do
       presenter = Class.new(Curly::Presenter) do
         version 42