start fix for issue #249

  - should standardize how we coerced Integer/Float values in pb
  - need to coerce value in Varint to make sure it is in bounds
  - bounds should be inclusive

lib/protobuf/field/bool_field.rb

@@ -20,6 +20,10 @@ def acceptable?(val)
         [true, false].include?(val)
       end
 
+      def coerce!(val)
+        val
+      end
+
       def decode(value)
         value == 1
       end

lib/protobuf/field/bytes_field.rb

@@ -60,7 +60,7 @@ def define_setter
             begin
               val = "#{val}" if val.is_a?(Symbol)
 
-              if val.nil?
+              if val.nil? || (val.respond_to?(:empty?) && val.empty?)
                 @values.delete(field.name)
               elsif field.acceptable?(val)
                 @values[field.name] = val.dup

lib/protobuf/field/varint_field.rb

@@ -7,7 +7,6 @@ class VarintField < BaseField
       ##
       # Constants
       #
-
       INT32_MAX  =  2**31 - 1
       INT32_MIN  = -2**31
       INT64_MAX  =  2**63 - 1
@@ -37,11 +36,18 @@ def self.encode(value)
       #
 
       def acceptable?(val)
-        (val > self.class.min || val < self.class.max)
+        return false unless val.respond_to?(:to_i)
+
+        coerced_value = coerce!(val)
+        coerced_value >= self.class.min && coerced_value <= self.class.max
       rescue
         false
       end
 
+      def coerce!(val)
+        Integer(val)
+      end
+
       def decode(value)
         value
       end