[Python-Dev] Recent changes to TextIOWrapper and its tests

[Jeff Allen]

I'm pulling recent changes in the io module across to Jython. I am 
looking for help understanding the changes in
http://hg.python.org/cpython/rev/19a33ef3821d

That change set is about what should happen if the underlying buffer 
does not return bytes when read, but instead, for example, unicode 
characters. The test test_read_nonbytes() constructs a pathological text 
stream reader t where the usual BytesIO or BufferedReader is replaced 
with a StringIO. It then checks that r.read(1) and t.readlines() raise a 
TypeError, that is, it tests that TextIOWrapper checks the type of what 
it reads from the buffer.

The puzzle is that it requires t.read() to succeed.

When I insert a check for bytes type in all the places it seems 
necessary in my code, I pass the first two conditions, but since 
t.read() also raises TypeError, the overall test fails. Is reading the 
stream with read() intended to succeed? Why is this desired?

Jeff Allen