isatty and capsys/capfd

[danizen]

I've written a class to enhance the progress module providing my own "ChunkedSpinner" and "DotCounter". To properly test these, I should make sure they are printing respectively a spinning character or a dot every 50 calls to report progress - this is the point, to make sure that progress reporting doesn't make everything slower.

However, the progress module uses the isatty call to prevent output, and I'm wondering how that will play with capsys. For now, I am just testing that my code doesn't blow up and that the count of progression remains the same even with the chunking. Any suggestions?