MONGOID-5222 fix regexp mongoization

Author: neilshweky

lib/mongoid/extensions/regexp.rb

@@ -18,7 +18,9 @@ module ClassMethods
         def mongoize(object)
           return if object.nil?
           case object
-          when String, ::Regexp then ::Regexp.new(object)
+          when String then ::Regexp.new(object)
+          when ::Regexp then object
+          when BSON::Regexp::Raw then object.compile
           else raise Errors::InvalidValue.new(self, object)
           end
         end

spec/mongoid/extensions/regexp_spec.rb

@@ -61,6 +61,17 @@
         expect(value).to be_nil
       end
     end
+
+    context "when providing a BSON::Regexp::Raw" do
+
+      let(:value) do
+        Regexp.mongoize(BSON::Regexp::Raw.new("hello"))
+      end
+
+      it "returns a Regexp" do
+        expect(value).to eq(/hello/)
+      end
+    end
   end
 
   describe "#mongoize" do