swev-id: pytest-dev__pytest-7521 preserve CR in capfd

[casey-brooks]

Summary

• disable universal newline translations in FDCaptureBinary to preserve carriage returns
• add regression tests for stdout/stderr CR and CRLF handling

Issue

• Closes capfd.readouterr() converts \r to \n in pytest 6.0.0rc1 (regression) #32

Regression

• Regression introduced in 29e4cb5
• Reproducer:

def test_capfd_includes_carriage_return(capfd):
    print("Greetings from DOS", end="\r")
    out, err = capfd.readouterr()
    assert out.endswith("\r")

• Failure before fix:

$ PYTHONPATH=src PYTEST_DISABLE_PLUGIN_AUTOLOAD=1 PYTEST_ADDOPTS=--assert=plain python -m pytest -q testing/test_capture_capfd_cr.py::test_capfd_includes_carriage_return
F                                                                        [100%]
=================================== FAILURES ===================================
_____________________ test_capfd_includes_carriage_return ______________________

capfd = <_pytest.capture.CaptureFixture object at 0xffff9286a150>

    def test_capfd_includes_carriage_return(capfd):
        print('Greetings from DOS', end='\r')
        out, err = capfd.readouterr()
>       assert out.endswith('\r')
E       AssertionError

testing/test_capture_capfd_cr.py:4: AssertionError
=========================== short test summary info ============================
FAILED testing/test_capture_capfd_cr.py::test_capfd_includes_carriage_return
1 failed in 0.02s

Testing

• PYTHONPATH=src PYTEST_DISABLE_PLUGIN_AUTOLOAD=1 PYTEST_ADDOPTS=--assert=plain python -m pytest -q testing/test_capture_capfd_cr.py
• flake8 --extend-ignore=F821 src/_pytest/capture.py testing/test_capture_capfd_cr.py

[casey-brooks]

Local verification:\n- PYTHONPATH=src PYTEST_DISABLE_PLUGIN_AUTOLOAD=1 PYTEST_ADDOPTS=--assert=plain python -m pytest -q testing/test_capture_capfd_cr.py (3 passed)\n- flake8 --extend-ignore=F821 src/_pytest/capture.py testing/test_capture_capfd_cr.py (no lint issues)

[noa-lucent]

Fix looks correct: disabling universal newline translation in FDCaptureBinary preserves CR/CRLF and the new regression tests cover stdout/stderr paths.