Running `pytest | head -1` and similar causes an annoying error to be
printed to stderr:
Exception ignored in: <_io.TextIOWrapper name='<stdout>' mode='w' encoding='utf-8'>
BrokenPipeError: [Errno 32] Broken pipe
(or possibly even a propagating exception in older/other Python versions).
The standard UNIX behavior is to handle the EPIPE silently. To
recommended method to do this in Python is described here:
https://docs.python.org/3/library/signal.html#note-on-sigpipe
It is not appropriate to apply this recommendation to `pytest.main()`,
which is used programmatically for in-process runs. Hence, change
pytest's entrypoint to a new `pytest.console_main()` function, to be
used exclusively by pytest's CLI, and add the SIGPIPE code there.
Fixes#4375.
When setting up the warnings capture, filter strings (with the general
form `action:message:category:module:line`) are collected from the
cmdline, ini and item and applied. This happens for every test and other
cases.
To apply a string it needs to be parsed into a tuple, and it turns out
this is slow. Since we already vendor the parsing code from Python's
warnings.py, we can speed it up by caching the result. After splitting
the parsing part from the applying part, the parsing is pure and is
straightforward to cache.
An alternative is to parse ahead of time and reuse the result, however
the caching solution turns out cleaner and more general in this case.
On this benchmark:
import pytest
@pytest.mark.parametrize("x", range(5000))
def test_foo(x): pass
Before:
============================ 5000 passed in 14.11s =============================
14365646 function calls (13450775 primitive calls) in 14.536 seconds
After:
============================ 5000 passed in 13.61s =============================
13290372 function calls (12375498 primitive calls) in 14.034 seconds
- replace "tests with warnings" with just warnings: they a) might not
come from a test in the first place, and b) a single test might have
multiple warnings.
- fix usage of (unused) argument to `collapsed_location_report`
Co-authored-by: Ran Benita <ran@unusedvar.com>
Move {Passthrough,CaptureIO} to capture module, and rename Passthrough
-> Tee to match the existing terminology.
Co-authored-by: Ran Benita <ran@unusedvar.com>
