Fix dynamic constant assignment error

Author: zetachang

spec/react/refs_callback_spec.rb

@@ -1,3 +1,7 @@
+require 'spec_helper'
+
+if opal?
+
 describe 'Refs callback' do
   before do
     stub_const 'Foo', Class.new
@@ -15,36 +19,32 @@ def render
       end
     end
 
-    stub_const 'MyBar', nil
     Foo.class_eval do
-      def my_bar=(bar)
-        MyBar = bar
-      end
+      attr_accessor :my_bar
 
       def render
         React.create_element(Bar, ref: method(:my_bar=).to_proc)
       end
     end
 
     element = React.create_element(Foo)
-    React::Test::Utils.render_into_document(element)
-    expect(MyBar).to be_a(Bar)
+    instance = React::Test::Utils.render_into_document(element)
+    expect(instance.my_bar).to be_a(Bar)
   end
 
   it "is invoked with the actual DOM node" do
-    stub_const 'MyDiv', nil
     Foo.class_eval do
-      def my_div=(div)
-        MyDiv = div
-      end
+      attr_accessor :my_div
 
       def render
         React.create_element('div', ref: method(:my_div=).to_proc)
       end
     end
 
     element = React.create_element(Foo)
-    React::Test::Utils.render_into_document(element)
-    expect(`#{MyDiv}.nodeType`).to eq(1)
+    instance = React::Test::Utils.render_into_document(element)
+    expect(`#{instance.my_div}.nodeType`).to eq(1)
   end
 end
+
+end