I've been working in a fix of PharoFilesOpener and decided to test the current behavior first before changing it, so I extracted the dependency to FileSystem and tried to use an instance created through FileSystem memory for testing.

The code gets the write stream for a file and then sends the #isReadOnly message to do some stuff.

The thing is that the streams returned form the in-memory file system are instances of WriteStream (see MemoryHandle >> writeStream) instead of StandardFileStream (see FileHandle >> writeStream) and so they don't respond the #isReadOnly message.

Is this the expected way the in-memory file system should work? Shouldn't it return polymorphic file streams?

If this is a bug, what change would you recommend to do?

I was thinking about returning StandardFileStreams instances from MemoryHandle >> writeStream.

Cheers!

Nico PM