function's return value should be converted to Ruby

(when invoked Ruby #call style)

lib/rhino/rhino_ext.rb

@@ -165,7 +165,8 @@ class Java::OrgMozillaJavascript::BaseFunction
     # calling as a (var) stored function - no this === undefined "use strict"
     # TODO can't pass Undefined.instance as this - it's not a Scriptable !?
     this = Rhino::JS::ScriptRuntime.getGlobal(context)
-    __call__(context, scope, this, Rhino.args_to_javascript(args, scope))
+    js_args = Rhino.args_to_javascript(args, scope)
+    Rhino.to_ruby __call__(context, scope, this, js_args)
   rescue Rhino::JS::JavaScriptException => e
     raise Rhino::JSError.new(e)
   ensure

spec/rhino/rhino_ext_spec.rb

@@ -158,10 +158,22 @@ describe "NativeFunction" do
   
   it_should_behave_like 'ScriptableObject'
   
-  it 'is callable' do
+  it 'is (Ruby) callable' do
     # NOTE: no implicit or bound this thus this === global
     @object.call.should == '[object global]'
   end
+
+  it 'is (Ruby) callable passing arguments' do
+    js = "( function foo(arg) { return 'foo' + arg; } )"
+    foo = @context.evaluateString(@scope, js, '<eval>', 0, nil)
+    foo.call(42).should == 'foo42'
+  end
+
+  it 'is (Ruby) callable converting result' do
+    js = "( function foo(arg) { return [ 1, 2, arg ]; } )"
+    foo = @context.evaluateString(@scope, js, '<eval>', 0, nil)
+    foo.call('x').should == [ 1, 2, 'x' ]
+  end
   
   it 'might be bind and called' do
     @object.bind(@object).should be_a(Rhino::JS::Function)