RUBY-222 BSON::Code must be a string.

lib/bson/types/code.rb

@@ -32,6 +32,10 @@ module BSON
     def initialize(code, scope={})
       @code  = code
       @scope = scope
+
+      unless @code.is_a?(String)
+        raise ArgumentError, "BSON::Code must be in the form of a String; #{@code.class} is not allowed."
+      end
     end
 
     def length

test/bson/bson_test.rb

@@ -150,6 +150,12 @@ class BSONTest < Test::Unit::TestCase
     assert_doc_pass(doc)
   end
 
+  def test_code_with_symbol
+    assert_raise_error ArgumentError, "BSON::Code must be in the form of a String" do
+      Code.new(:fubar)
+    end
+  end
+
   def test_code_with_scope
     doc = {'$where' => Code.new('this.a.b < this.b', {'foo' => 1})}
     assert_doc_pass(doc)