capsys interferes with debugging
I used capsys to test the output of a function that prints to stdout. The function failed before the capsys.readouterr() line, and its output was essential to determining what went wrong. The FAILURES list in py.test did not contain any of the output. It seems that in this situation, py.test should print all of the captured output in the FAILURES list, as it would if capsys were not present.
The following paste shows a minimal example with and without capsys:
Note that for test_nocap, "hi" appears in the "captured stdout", but for test_capsys, this information is unavailable. It seems to me that "hi" should be shown for both cases.
Thanks for the work you put into pytest; it's a great project.