Handle string field names in CustomFieldList#respond_to?

Previously `respond_to?` assumed it was given a symbol argument, so it
directly checked for that argument in the fields, which are force-keyed
as symbols. If you passed it a string argument, it wouldn't find the
corresponding field, impying it didn't respond to such a method.

Now, the argument is explicitly cast to a symbol before checking if such
a field exists, supporting checking `respond_to?` with both argument
types.

HISTORY.md

@@ -6,6 +6,7 @@
 
 ### Fixed
 * Revert recent proxy changes which breaks proxy usage by @andrewdicken-stripe in https://github.com/NetSweet/netsuite/pull/579
+* Handle string field names in `CustomFieldList#respond_to?` (#606)
 
 ### Breaking Changes
 

lib/netsuite/records/custom_field_list.rb

@@ -60,8 +60,8 @@ def method_missing(sym, *args, &block)
         super(sym, *args, &block)
       end
 
-      def respond_to?(sym, include_private = false)
-        return true if @custom_fields_assoc.include?(sym)
+      def respond_to?(method, include_private = false)
+        return true if @custom_fields_assoc.include?(method.to_sym)
         super
       end
 

spec/netsuite/records/custom_field_list_spec.rb

@@ -273,8 +273,14 @@
 
         # field accessors are tested elsewhere, but let's run tests here to check various field types
         expect(list).to respond_to(:custbody_multipleselectfield)
+        expect(list).to respond_to('custbody_multipleselectfield')
         expect(list).to respond_to(:custbody_salesclassification)
+        expect(list).to respond_to('custbody_salesclassification')
         expect(list).to respond_to(:custentity_registeredonline)
+        expect(list).to respond_to('custentity_registeredonline')
+
+        expect(list).to_not respond_to(:non_existant_field)
+        expect(list).to_not respond_to('non_existant_field')
 
         expect(list.to_record).to eql(record)
         expect(list.to_record.length).to eq(1)