[jseop-lim]

Description

Fixes #1252

TeeDataObjectBuiltins.InitNode required only $self and had two specializations that took values=None as an empty buffer, so _tee_dataobject accepted None for values and fewer than three arguments. CPython requires exactly three positional arguments and a list for values (itertoolsmodule.c.h#L244-L251).

AS-IS

>>> itertools._tee_dataobject(iter([]), None, None)
<itertools._tee_dataobject object at 0x...>
>>> itertools._tee_dataobject(iter([]), [])
<itertools._tee_dataobject object at 0x...>
>>> itertools._tee_dataobject(iter([]), None, 5)
Unexpected values provided for TeeDataObjectBuiltinsFactory.InitNodeFactory.InitNodeGen@...

TO-BE

>>> itertools._tee_dataobject(iter([]), None, None)
TypeError: teedataobject() argument 2 must be list, not NoneType
>>> itertools._tee_dataobject(iter([]), [])
TypeError: TeeDataObject() missing 1 required positional argument: 'nxt'
>>> itertools._tee_dataobject(iter([]), None, 5)
TypeError: teedataobject() argument 2 must be list, not NoneType

(same exception types as CPython; the messages differ in wording)

Changes

• Raise minNumOfPositionalArgs of InitNode to 4, so it, values and nxt are all required.
• Remove the two isNone(values) specializations and their helper, and guard the TypeError specialization with !isList(values) alone.
• Add tests/test_itertools_teedataobject.py.

Testing

mx python-jvm on darwin-aarch64, then the new test_itertools_teedataobject.py (3 passed) and the tagged test_itertools (124 passed). The new test fails on the unpatched build. _tee_dataobject(iter([]), [1], None) still creates an object, and tee() and copy() of a tee still work.