fix: mimic JS behavior for delete(obj.foo)

lib/proto.rb

@@ -30,7 +30,12 @@ def prototype
   #   traversed through instead.
   def [](property)
     property = property.to_s
-    property?(property) ? @table[property] : (@proto and @proto[property])
+    if property?(property)
+      @table[property]
+    else
+      return nil unless @proto
+      @proto.public_send(property)
+    end
   end
 
   ##
@@ -133,9 +138,8 @@ def __add(property, value)
 
   def __delete(property)
     @table.delete(property)
-    @proto&.delete(property)
     return unless instance_of?(method(property).owner)
-    define_singleton_method(property) { nil }
+    define_singleton_method(property) { self[property] }
   rescue NameError
   end
 end

spec/object_mixin_spec.rb

@@ -12,34 +12,35 @@
   let(:three) { object.create(two) }
 
   context "when there is one prototype in the chain" do
-    context "when falling back to the property on the root prototype" do
+    context "when traversing to the property on the root prototype" do
       subject { two.bar }
       it { is_expected.to eq(42) }
     end
 
     context "when the property is deleted from the root prototype" do
-      before { two.delete("bar") }
+      before { one.delete("bar") }
       subject { two.bar }
       it { is_expected.to eq(nil) }
     end
   end
 
   context "when there are two prototypes in the chain" do
-    context "when falling back to the property on the root prototype" do
+    context "when traversing to the property on the root prototype" do
       subject { three.bar }
       it { is_expected.to eq(42) }
     end
 
-    context "when falling back to the property on the middle prototype" do
+    context "when traversing to the property on the middle prototype" do
       let(:two) { object.create(one) { def bar = 84 } }
       subject { three.bar }
       it { is_expected.to eq(84) }
     end
 
-    context "when the property is deleted from all prototypes in the chain" do
+    context "when the property is deleted from the middle prototype" do
+      let(:two) { object.create(one) { def bar = 84 } }
       before { two.delete("bar") }
-      subject { two.bar }
-      it { is_expected.to eq(nil) }
+      subject { three.bar }
+      it { is_expected.to eq(42) }
     end
   end
 end