mcaxl/tests/test_to_int_diagnostic.py

"""Hamilton review MINOR #6: `_to_int` silently coerced bad values to None.

Sort fields built on `_to_int` returns then defaulted None to 0, which
jumbled the failover order in the displayed result. Fix: when the conversion
fails, log to stderr (so an operator can see) and return None — but the
caller code path that does the sort now uses a stable tie-breaker that
doesn't silently rewrite real-zero into "no value."
"""

import sys
from io import StringIO

from mcaxl.route_plan import _to_int


def test_to_int_passthrough_normal():
    assert _to_int("5") == 5
    assert _to_int(7) == 7


def test_to_int_none_returns_none_silently():
    """Real Nones are valid (column not set) — don't log noise for them."""
    captured = StringIO()
    real_stderr = sys.stderr
    sys.stderr = captured
    try:
        assert _to_int(None) is None
    finally:
        sys.stderr = real_stderr
    assert "warning" not in captured.getvalue().lower()


def test_to_int_bad_value_logs_warning():
    """A non-numeric string from the cluster (data corruption / unexpected
    type) should be loud enough for an operator to notice in stderr."""
    captured = StringIO()
    real_stderr = sys.stderr
    sys.stderr = captured
    try:
        result = _to_int("not-a-number")
    finally:
        sys.stderr = real_stderr
    assert result is None
    output = captured.getvalue()
    assert "not-a-number" in output, (
        f"unexpected non-numeric value should be logged with the offending value; "
        f"got stderr: {output!r}"
    )