Raise NoMethodError for unknown fields

More informative and more ruby-like

ruby/ext/google/protobuf_c/message.c

@@ -166,7 +166,7 @@ VALUE Message_method_missing(int argc, VALUE* argv, VALUE _self) {
                                           name, name_len);
 
   if (f == NULL) {
-    rb_raise(rb_eArgError, "Unknown field");
+    return rb_call_super(argc, argv);
   }
 
   if (setter) {

ruby/src/main/java/com/google/protobuf/jruby/RubyMessage.java

@@ -217,6 +217,9 @@ public class RubyMessage extends RubyObject {
             RubyDescriptor rubyDescriptor = (RubyDescriptor) getDescriptor(context, metaClass);
             IRubyObject oneofDescriptor = rubyDescriptor.lookupOneof(context, args[0]);
             if (oneofDescriptor.isNil()) {
+                if (!hasField(args[0])) {
+                    throw context.runtime.newNoMethodError("undefined method `" + args[0].toString() + "' for " + metaClass.toString(), args[0].asJavaString(),  metaClass);
+                }
                 return index(context, args[0]);
             }
             RubyOneofDescriptor rubyOneofDescriptor = (RubyOneofDescriptor) oneofDescriptor;
@@ -233,6 +236,10 @@ public class RubyMessage extends RubyObject {
             if (field.end_with_p(context, equalSign).isTrue()) {
                 field.chomp_bang(context, equalSign);
             }
+
+            if (!hasField(field)) {
+                throw context.runtime.newNoMethodError("undefined method `" + args[0].asJavaString() + "' for " + metaClass.toString(), args[0].asJavaString(),  metaClass);
+            }
             return indexSet(context, field, args[1]);
         }
     }
@@ -435,6 +442,11 @@ public class RubyMessage extends RubyObject {
         return ret;
     }
 
+    private boolean hasField(IRubyObject fieldName) {
+        String nameStr = fieldName.asJavaString();
+        return this.descriptor.findFieldByName(Utils.escapeIdentifier(nameStr)) != null;
+    }
+
     private void checkRepeatedFieldType(ThreadContext context, IRubyObject value,
                                         Descriptors.FieldDescriptor fieldDescriptor) {
         Ruby runtime = context.runtime;

ruby/tests/basic.rb

@@ -191,6 +191,18 @@ module BasicTest
       assert m1.hash != m2.hash
     end
 
+    def test_unknown_field_errors
+      e = assert_raise NoMethodError do
+        TestMessage.new.hello
+      end
+      assert_match(/hello/, e.message)
+
+      e = assert_raise NoMethodError do
+        TestMessage.new.hello = "world"
+      end
+      assert_match(/hello/, e.message)
+    end
+
     def test_type_errors
       m = TestMessage.new
       assert_raise TypeError do