`DirectoryMonitor` behavior on file rename can be surprising

[ranweiler]

The following is arguably not a bug, but is a subtlety that should at least be documented.

Suppose we have:

• An outer directory outer and a child directory outer/watched
• A DirectoryMonitor that is watching the child dir, outer/watched
• No other files or directories

The following shell transcript will result in the monitor reporting the creation of 1 file, myfile.txt:

cd outer

# Create `myfile.txt` in `outer`.
touch myfile.txt

# Move the file into the watched directory.
# 
# This is reported by the monitor.
mv myfile.txt ./watched/myfile.txt

Counterintuitively, from a clean slate, the following shell transcript will result in the monitor reporting the creation of 1 file, .tmp.txt.

cd outer/watched

# This is reported by the monitor.
touch .tmp.txt

# This is NOT reported as a created file.
mv .tmp.txt myfile.txt

This is true on both Linux and Windows.

AB#35926

[mgreisen]

@ranweiler is this still true? Did you change the DirectoryMonitor?

[ranweiler]

I believe this is still true.

To change this, we'd add a new case here. I suspect that we just need to watch for a Modify event with ModifyKind of Name.

[Porges]

This has been fixed in #3195. Renames inside the monitored directory now produce a notification.