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glenn schrooyenandClaude Opus 5.5 770988c902
checks / unit (pull_request) Successful in 8m44s
TEST-26: a missing value in a check is a named FAIL, not a traceback
Checks and prints that indexed an empty list, exhausted next(), or formatted
None killed the rest of their file (FCST-06). Read them through the new
named_absence.py (nth/first/field/given/present) and conjoin a presence term.

- every site in the brief, plus the family the new scan and a sweep found
- test_named_absence.py: scans every test_*.py for unguarded filtered-list
  indexing, next() without a default and numeric formats on maybe-None
  names; proven to bite; prints what it cannot see, counted
- test_price.py 16a: the `_T17_CAPS is _T17_CAPS` tautology now grades the
  two assemble() calls' arguments
- test_control.py: coverage table re-measured on runs graded to the end

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01BwRLw7eKYj2byVdwB6kbjU
2026-09-25 00:06:58 +02:00

100 lines
2.6 KiB
Python

"""Read a value a check prints or grades without raising (TEST-26).
Each test file is one script, so an IndexError in a print or a check name
kills every check after it (MUTATION.md, FCST-06). Read through these instead,
and conjoin `present(x)` in the check so the absence grades as a named FAIL.
`ABSENT` values never raise: they format as `<ABSENT ...>` under any spec,
index and attribute to themselves, compare unequal AND not-unequal, and are
falsy. `not x`, `"a" not in x` and `all(... for _ in x)` are therefore TRUE of
one, which is why the check needs the `present()` term. `int()`, `range()` and
use as a list index still raise: guard those with `present()`.
"""
_NAN = float("nan")
class Absent:
__slots__ = ("what",)
def __init__(self, what):
object.__setattr__(self, "what", what)
def __repr__(self):
return f"<ABSENT {self.what}>"
__str__ = __repr__
def __format__(self, spec):
return repr(self)
def __bool__(self):
return False
def __eq__(self, other):
return False
__ne__ = __lt__ = __le__ = __gt__ = __ge__ = __eq__
def __hash__(self):
return id(self)
def __getitem__(self, _):
return self
def __getattr__(self, _):
return self
def __call__(self, *_a, **_k):
return self
def __len__(self):
return 0
def __iter__(self):
return iter(())
def __contains__(self, _):
return False
def __float__(self):
return _NAN
def _same(self, *_):
return self
__add__ = __radd__ = __sub__ = __rsub__ = __mul__ = __rmul__ = _same
__truediv__ = __rtruediv__ = __floordiv__ = __rfloordiv__ = _same
__mod__ = __rmod__ = __neg__ = __pos__ = __abs__ = __round__ = _same
def present(*xs):
"""True when none of `xs` is an ABSENT stand-in."""
return not any(isinstance(x, Absent) for x in xs)
def nth(seq, i=0, what=None):
"""`seq[i]`, or an ABSENT saying how many items there were."""
n = 0 if seq is None else len(seq)
if -n <= i < n:
return seq[i]
return Absent(what or f"[{i}] of {n} item(s)")
def first(it, what="no match"):
"""`next(it)`, or ABSENT when it is exhausted."""
return next(iter(it), Absent(what))
def field(mapping, key, what=None):
"""`mapping[key]`, or ABSENT when the key (or the mapping) is missing."""
try:
return mapping[key]
except (KeyError, IndexError, TypeError):
return Absent(what or f"key {key!r}")
def given(x, what="None"):
"""`x`, or ABSENT when it is None - so `:.2f` and arithmetic cannot raise."""
return Absent(what) if x is None else x