When using the GameTest framework, you can look up the amount of an item stack. According to the documentation, this amount property is read/write (while the other properties on the item stack are read-only). 

However, trying to change the amount in the stack by changing the value (which I assume is the intended use for the r/w-ness of the property), the stack in the game is not updated and keeps the amount as is.

Reading the value after setting it does return the updated value.

I don't know if this is intentional, but if it is, I don't think having this property as r/w doesn't make sense as it creates the wrong expectations. I would rather have it to work as I expect to, though.

I'm building this on a Windows 11 PC, but it would apply for all platforms using Realms or a server.