tempfile.NamedTemporaryFile use case?

[Roy Smith]

What is the use case for tempfile.NamedTemporaryFile?  As far as I can 
tell, the only way it differs from TemporaryFile is that it is 
guaranteed to have a name in the file system.  BUT, it's not guaranteed 
that you can open the file a second time via that name.

So, what's the point?  In what situations would NamedTemporaryFile do 
what you want but TemporaryFile not?

I'm writing a unit test where I want to verify operation of my code on a 
path which can't be opened (i.e. that it raises IOError). 
NamedTemporaryFile almost gives me what I want.  It creates a file, 
tells me what the path is (so I can os.chmod() it to mode 0), and cleans 
it up when I'm done (so I don't have to write my own context manager or 
whatever).  But, it's not guaranteed that I can open the path, so the 
whole test is moot.

I can work around that (plain old mktemp() or mkstemp() and have my 
tearDown() method do the cleanup), but the more I look at this, the more 
I'm scratching my head why NamedTemporaryFile exists.