added some tests

spec/models/hint_spec.rb

@@ -28,4 +28,10 @@ describe Hint do
       expect(Hint.nested_resource?).to be true
     end
   end
+
+  describe '#to_s' do
+    it "equals the hint's name" do
+      expect(hint.to_s).to eq(hint.name)
+    end
+  end
 end

spec/models/submission_spec.rb

@@ -32,4 +32,10 @@ describe Submission do
       end
     end
   end
+
+  describe '#to_s' do
+    it "equals the class' model name" do
+      expect(@submission.to_s).to eq(Submission.model_name.human)
+    end
+  end
 end