Rework solution for #1

lib/strict_open_struct.rb

@@ -12,7 +12,7 @@ def method_missing(method_name, *args, &block)
     if open_struct_responds_to?(method_name)
       @open_struct.send(method_name, *args, &block)
     else
-      fail NoMethodError, "undefined method `#{method_name}' for #{self}"
+      failure(method_name)
     end
   end
 
@@ -25,11 +25,15 @@ def ==(other)
   end
 
   def [](key)
-    self.send(key)
+    @open_struct.to_h.fetch(key.to_sym)
   end
 
   private
 
+  def failure(method_name)
+    fail NoMethodError, "undefined method `#{method_name}' for #{self}"
+  end
+
   def open_struct_responds_to?(method_name)
     @open_struct.respond_to?(method_name) || method_name =~ /=$/
   end

test/basic_test.rb

@@ -52,7 +52,7 @@ def first_name
     end
 
     specify "raises an exception if key is undefined" do
-      assert_raises NoMethodError do
+      assert_raises KeyError do
         StrictOpenStruct.new[:a]
       end
     end