testProperty not changing #1

I have an issue where the custom object's testProperty does not change from the script.

I have modified the line:

context.globalObject.setValue(JSCustomObject(), forProperty: "customObject")

to:

var customObject = JSCustomObject()
context.globalObject.setValue(customObject, forProperty: "customObject")

in order to observe the customObject's property change, but it doesn't change. It is supposed to change, right?