Amaury, thanks for your valuable feedback.

1. I forgot about the python implementation. I am not familiar with the new IO framework. Implemented now.

3. These new SEEK modes should not be used in text mode. In my new patch the modes are rejected in text mode, allowed in binary mode.

2. I have spend the last 3 hours studying "test_io.py", and I don't understand the Mock* usage. Your MockRawIO hint is valuable, but I can't think a way to test that C/Python implementation passes the new flags to the OS. If I understand correctly, any method implemented in the Mock will be hit instead of the IO implementation, and anything that reach IO implementation will not go back to the Mock. I don't understand... :-?. Or can you magically insert the Mock between the IO module and the OS?. I know something like this is happening, but I don't understand the mechanism.

How do you choose what Mock* are you using in each test?.

I have read about Mock testing in the past, but I don't understand the use here. Are they actually Mocks, as explained in http://agiletesting.blogspot.com/2009/07/python-mock-testing-techniques-and.html , for example?

Sorry.

Could you provide some hint?. Maybe in python-dev, for more audience?.

I have implemented a test "test_posix", if your OS can report holes in a file (so far modern Solaris/OpenSolaris/OpenIndiana, don't know about *bsd). Other OSs will ignore the test.

I know your time is valuable. Thanking for investing in me.