From the documentation:

os.path.realpath(path)
Return the canonical path of the specified filename, eliminating any 
symbolic links encountered in the path (if they are supported by the 
operating system).

When I invoke this with an extant file's name, I get the path to it: /home/myhome/myproject.

When I invoke this with a 'nonsense.xxx' string argument, I still get a path to /home/myhome/myproject/nonsense.xxx. This is a little inconsistent because it looks like nonsense.xxx is taken to be a directory not a file (though it is neither: it does not exist).

When I invoke this with a null string file name, I still get a path to /home/myhome/myproject.

How can I account for this behaviour when the documentation says so little about realpath()? (I am using Python 2.5.)

Edit: Somebody suggested a way to test if files exist. My concern is not to test if files exist. My concern is to account for behaviour.