fix: handle itertools types in comparator with Python 3.9-3.14 support

codeflash/verification/comparator.py

@@ -3,9 +3,11 @@
 import datetime
 import decimal
 import enum
+import itertools
 import math
 import re
 import types
+import warnings
 import weakref
 from collections import ChainMap, OrderedDict, deque
 from importlib.util import find_spec
@@ -528,6 +530,55 @@ def comparator(orig: Any, new: Any, superset_obj: bool = False) -> bool:
                 )
             return comparator(orig_dict, new_dict, superset_obj)
 
+        # Handle itertools infinite iterators
+        if isinstance(orig, itertools.count):
+            # repr reliably reflects internal state, e.g. "count(5)" or "count(5, 2)"
+            return repr(orig) == repr(new)
+
+        if isinstance(orig, itertools.repeat):
+            # repr reliably reflects internal state, e.g. "repeat(5)" or "repeat(5, 3)"
+            return repr(orig) == repr(new)
+
+        if isinstance(orig, itertools.cycle):
+            # cycle has no useful repr and no public attributes; use __reduce__ to extract state.
+            # __reduce__ returns (cls, (remaining_iter,), (saved_items, first_pass_done)).
+            # NOTE: consuming the remaining_iter is destructive to the cycle object, but this is
+            # acceptable since the comparator is the final consumer of captured return values.
+            # NOTE: __reduce__ on itertools.cycle was removed in Python 3.14.
+            try:
+                with warnings.catch_warnings():
+                    warnings.simplefilter("ignore", DeprecationWarning)
+                    orig_reduce = orig.__reduce__()
+                    new_reduce = new.__reduce__()
+                orig_remaining = list(orig_reduce[1][0])
+                new_remaining = list(new_reduce[1][0])
+                orig_saved, orig_started = orig_reduce[2]
+                new_saved, new_started = new_reduce[2]
+                if orig_started != new_started:
+                    return False
+                return comparator(orig_remaining, new_remaining, superset_obj) and comparator(
+                    orig_saved, new_saved, superset_obj
+                )
+            except TypeError:
+                # Python 3.14+: __reduce__ removed. Fall back to consuming elements from both
+                # cycles and comparing. Since the comparator is the final consumer, this is safe.
+                sample_size = 200
+                orig_sample = [next(orig) for _ in range(sample_size)]
+                new_sample = [next(new) for _ in range(sample_size)]
+                return comparator(orig_sample, new_sample, superset_obj)
+
+        # Handle remaining itertools types (chain, islice, starmap, product, permutations, etc.)
+        # by materializing into lists. count/repeat/cycle are already handled above.
+        # NOTE: materializing is destructive (consumes the iterator) and will hang on infinite input,
+        # but the three infinite itertools types are already handled above.
+        if type(orig).__module__ == "itertools":
+            if isinstance(orig, itertools.groupby):
+                # groupby yields (key, group_iterator) — materialize groups too
+                orig_groups = [(k, list(g)) for k, g in orig]
+                new_groups = [(k, list(g)) for k, g in new]
+                return comparator(orig_groups, new_groups, superset_obj)
+            return comparator(list(orig), list(new), superset_obj)
+
         # re.Pattern can be made better by DFA Minimization and then comparing
         if isinstance(
             orig, (datetime.datetime, datetime.date, datetime.timedelta, datetime.time, datetime.timezone, re.Pattern)

tests/test_comparator.py

@@ -417,6 +417,312 @@ class Color4(IntFlag):
     assert not comparator(id1, id3)
 
 
+def test_itertools_count() -> None:
+    import itertools
+
+    # Equal: same start and step (default step=1)
+    assert comparator(itertools.count(0), itertools.count(0))
+    assert comparator(itertools.count(5), itertools.count(5))
+    assert comparator(itertools.count(0, 1), itertools.count(0, 1))
+    assert comparator(itertools.count(10, 3), itertools.count(10, 3))
+
+    # Equal: negative start and step
+    assert comparator(itertools.count(-5, -2), itertools.count(-5, -2))
+
+    # Equal: float start and step
+    assert comparator(itertools.count(0.5, 0.1), itertools.count(0.5, 0.1))
+
+    # Not equal: different start
+    assert not comparator(itertools.count(0), itertools.count(1))
+    assert not comparator(itertools.count(5), itertools.count(10))
+
+    # Not equal: different step
+    assert not comparator(itertools.count(0, 1), itertools.count(0, 2))
+    assert not comparator(itertools.count(0, 1), itertools.count(0, -1))
+
+    # Not equal: different type
+    assert not comparator(itertools.count(0), 0)
+    assert not comparator(itertools.count(0), [0, 1, 2])
+
+    # Equal after partial consumption (both advanced to the same state)
+    a = itertools.count(0)
+    b = itertools.count(0)
+    next(a)
+    next(b)
+    assert comparator(a, b)
+
+    # Not equal after different consumption
+    a = itertools.count(0)
+    b = itertools.count(0)
+    next(a)
+    assert not comparator(a, b)
+
+    # Works inside containers
+    assert comparator([itertools.count(0)], [itertools.count(0)])
+    assert comparator({"key": itertools.count(5, 2)}, {"key": itertools.count(5, 2)})
+    assert not comparator([itertools.count(0)], [itertools.count(1)])
+
+
+def test_itertools_repeat() -> None:
+    import itertools
+
+    # Equal: infinite repeat
+    assert comparator(itertools.repeat(5), itertools.repeat(5))
+    assert comparator(itertools.repeat("hello"), itertools.repeat("hello"))
+
+    # Equal: bounded repeat
+    assert comparator(itertools.repeat(5, 3), itertools.repeat(5, 3))
+    assert comparator(itertools.repeat(None, 10), itertools.repeat(None, 10))
+
+    # Not equal: different value
+    assert not comparator(itertools.repeat(5), itertools.repeat(6))
+    assert not comparator(itertools.repeat(5, 3), itertools.repeat(6, 3))
+
+    # Not equal: different count
+    assert not comparator(itertools.repeat(5, 3), itertools.repeat(5, 4))
+
+    # Not equal: bounded vs infinite
+    assert not comparator(itertools.repeat(5), itertools.repeat(5, 3))
+
+    # Not equal: different type
+    assert not comparator(itertools.repeat(5), 5)
+    assert not comparator(itertools.repeat(5), [5])
+
+    # Equal after partial consumption
+    a = itertools.repeat(5, 5)
+    b = itertools.repeat(5, 5)
+    next(a)
+    next(b)
+    assert comparator(a, b)
+
+    # Not equal after different consumption
+    a = itertools.repeat(5, 5)
+    b = itertools.repeat(5, 5)
+    next(a)
+    assert not comparator(a, b)
+
+    # Works inside containers
+    assert comparator([itertools.repeat(5, 3)], [itertools.repeat(5, 3)])
+    assert not comparator([itertools.repeat(5, 3)], [itertools.repeat(5, 4)])
+
+
+def test_itertools_cycle() -> None:
+    import itertools
+
+    # Equal: same sequence
+    assert comparator(itertools.cycle([1, 2, 3]), itertools.cycle([1, 2, 3]))
+    assert comparator(itertools.cycle("abc"), itertools.cycle("abc"))
+
+    # Not equal: different sequence
+    assert not comparator(itertools.cycle([1, 2, 3]), itertools.cycle([1, 2, 4]))
+    assert not comparator(itertools.cycle([1, 2, 3]), itertools.cycle([1, 2]))
+
+    # Not equal: different type
+    assert not comparator(itertools.cycle([1, 2, 3]), [1, 2, 3])
+
+    # Equal after same partial consumption
+    a = itertools.cycle([1, 2, 3])
+    b = itertools.cycle([1, 2, 3])
+    next(a)
+    next(b)
+    assert comparator(a, b)
+
+    # Not equal after different consumption
+    a = itertools.cycle([1, 2, 3])
+    b = itertools.cycle([1, 2, 3])
+    next(a)
+    assert not comparator(a, b)
+
+    # Equal after consuming a full cycle
+    a = itertools.cycle([1, 2, 3])
+    b = itertools.cycle([1, 2, 3])
+    for _ in range(3):
+        next(a)
+        next(b)
+    assert comparator(a, b)
+
+    # Equal at same position across different full-cycle counts
+    a = itertools.cycle([1, 2, 3])
+    b = itertools.cycle([1, 2, 3])
+    for _ in range(4):
+        next(a)
+    for _ in range(7):
+        next(b)
+    # Both at position 1 within the cycle (4%3 == 7%3 == 1)
+    assert comparator(a, b)
+
+    # Works inside containers
+    assert comparator([itertools.cycle([1, 2])], [itertools.cycle([1, 2])])
+    assert not comparator([itertools.cycle([1, 2])], [itertools.cycle([1, 3])])
+
+
+def test_itertools_chain() -> None:
+    import itertools
+
+    assert comparator(itertools.chain([1, 2], [3, 4]), itertools.chain([1, 2], [3, 4]))
+    assert not comparator(itertools.chain([1, 2], [3, 4]), itertools.chain([1, 2], [3, 5]))
+    assert comparator(itertools.chain.from_iterable([[1, 2], [3]]), itertools.chain.from_iterable([[1, 2], [3]]))
+    assert comparator(itertools.chain(), itertools.chain())
+    assert not comparator(itertools.chain([1]), itertools.chain([1, 2]))
+
+
+def test_itertools_islice() -> None:
+    import itertools
+
+    assert comparator(itertools.islice(range(10), 5), itertools.islice(range(10), 5))
+    assert not comparator(itertools.islice(range(10), 5), itertools.islice(range(10), 6))
+    assert comparator(itertools.islice(range(10), 2, 5), itertools.islice(range(10), 2, 5))
+    assert not comparator(itertools.islice(range(10), 2, 5), itertools.islice(range(10), 2, 6))
+
+
+def test_itertools_product() -> None:
+    import itertools
+
+    assert comparator(itertools.product("AB", repeat=2), itertools.product("AB", repeat=2))
+    assert not comparator(itertools.product("AB", repeat=2), itertools.product("AC", repeat=2))
+    assert comparator(itertools.product([1, 2], [3, 4]), itertools.product([1, 2], [3, 4]))
+    assert not comparator(itertools.product([1, 2], [3, 4]), itertools.product([1, 2], [3, 5]))
+
+
+def test_itertools_permutations_combinations() -> None:
+    import itertools
+
+    assert comparator(itertools.permutations("ABC", 2), itertools.permutations("ABC", 2))
+    assert not comparator(itertools.permutations("ABC", 2), itertools.permutations("ABD", 2))
+    assert comparator(itertools.combinations("ABCD", 2), itertools.combinations("ABCD", 2))
+    assert not comparator(itertools.combinations("ABCD", 2), itertools.combinations("ABCD", 3))
+    assert comparator(
+        itertools.combinations_with_replacement("ABC", 2),
+        itertools.combinations_with_replacement("ABC", 2),
+    )
+    assert not comparator(
+        itertools.combinations_with_replacement("ABC", 2),
+        itertools.combinations_with_replacement("ABD", 2),
+    )
+
+
+def test_itertools_accumulate() -> None:
+    import itertools
+
+    assert comparator(itertools.accumulate([1, 2, 3, 4]), itertools.accumulate([1, 2, 3, 4]))
+    assert not comparator(itertools.accumulate([1, 2, 3, 4]), itertools.accumulate([1, 2, 3, 5]))
+    assert comparator(itertools.accumulate([1, 2, 3], initial=10), itertools.accumulate([1, 2, 3], initial=10))
+    assert not comparator(itertools.accumulate([1, 2, 3], initial=10), itertools.accumulate([1, 2, 3], initial=0))
+
+
+def test_itertools_filtering() -> None:
+    import itertools
+
+    # compress
+    assert comparator(
+        itertools.compress("ABCDEF", [1, 0, 1, 0, 1, 1]),
+        itertools.compress("ABCDEF", [1, 0, 1, 0, 1, 1]),
+    )
+    assert not comparator(
+        itertools.compress("ABCDEF", [1, 0, 1, 0, 1, 1]),
+        itertools.compress("ABCDEF", [1, 1, 1, 0, 1, 1]),
+    )
+
+    # dropwhile
+    assert comparator(
+        itertools.dropwhile(lambda x: x < 5, [1, 4, 6, 4, 1]),
+        itertools.dropwhile(lambda x: x < 5, [1, 4, 6, 4, 1]),
+    )
+    assert not comparator(
+        itertools.dropwhile(lambda x: x < 5, [1, 4, 6, 4, 1]),
+        itertools.dropwhile(lambda x: x < 5, [1, 4, 7, 4, 1]),
+    )
+
+    # takewhile
+    assert comparator(
+        itertools.takewhile(lambda x: x < 5, [1, 4, 6, 4, 1]),
+        itertools.takewhile(lambda x: x < 5, [1, 4, 6, 4, 1]),
+    )
+    assert not comparator(
+        itertools.takewhile(lambda x: x < 5, [1, 4, 6, 4, 1]),
+        itertools.takewhile(lambda x: x < 5, [1, 3, 6, 4, 1]),
+    )
+
+    # filterfalse
+    assert comparator(
+        itertools.filterfalse(lambda x: x % 2, range(10)),
+        itertools.filterfalse(lambda x: x % 2, range(10)),
+    )
+
+
+def test_itertools_starmap() -> None:
+    import itertools
+
+    assert comparator(
+        itertools.starmap(pow, [(2, 3), (3, 2), (10, 0)]),
+        itertools.starmap(pow, [(2, 3), (3, 2), (10, 0)]),
+    )
+    assert not comparator(
+        itertools.starmap(pow, [(2, 3), (3, 2)]),
+        itertools.starmap(pow, [(2, 3), (3, 3)]),
+    )
+
+
+def test_itertools_zip_longest() -> None:
+    import itertools
+
+    assert comparator(
+        itertools.zip_longest("AB", "xyz", fillvalue="-"),
+        itertools.zip_longest("AB", "xyz", fillvalue="-"),
+    )
+    assert not comparator(
+        itertools.zip_longest("AB", "xyz", fillvalue="-"),
+        itertools.zip_longest("AB", "xyz", fillvalue="*"),
+    )
+
+
+def test_itertools_groupby() -> None:
+    import itertools
+
+    assert comparator(itertools.groupby("AAABBBCC"), itertools.groupby("AAABBBCC"))
+    assert not comparator(itertools.groupby("AAABBBCC"), itertools.groupby("AAABBCC"))
+    assert comparator(itertools.groupby([]), itertools.groupby([]))
+
+    # With key function
+    assert comparator(
+        itertools.groupby([1, 1, 2, 2, 3], key=lambda x: x),
+        itertools.groupby([1, 1, 2, 2, 3], key=lambda x: x),
+    )
+
+
+@pytest.mark.skipif(sys.version_info < (3, 10), reason="itertools.pairwise requires Python 3.10+")
+def test_itertools_pairwise() -> None:
+    import itertools
+
+    assert comparator(itertools.pairwise([1, 2, 3, 4]), itertools.pairwise([1, 2, 3, 4]))
+    assert not comparator(itertools.pairwise([1, 2, 3, 4]), itertools.pairwise([1, 2, 3, 5]))
+
+
+@pytest.mark.skipif(sys.version_info < (3, 12), reason="itertools.batched requires Python 3.12+")
+def test_itertools_batched() -> None:
+    import itertools
+
+    assert comparator(itertools.batched("ABCDEFG", 3), itertools.batched("ABCDEFG", 3))
+    assert not comparator(itertools.batched("ABCDEFG", 3), itertools.batched("ABCDEFG", 2))
+
+
+def test_itertools_in_containers() -> None:
+    import itertools
+
+    # Itertools objects nested in dicts/lists
+    assert comparator(
+        {"a": itertools.chain([1], [2]), "b": itertools.islice(range(5), 3)},
+        {"a": itertools.chain([1], [2]), "b": itertools.islice(range(5), 3)},
+    )
+    assert not comparator(
+        [itertools.product("AB", repeat=2)],
+        [itertools.product("AC", repeat=2)],
+    )
+
+    # Different itertools types should not match
+    assert not comparator(itertools.chain([1, 2]), itertools.islice([1, 2], 2))
+
+
 def test_numpy():
     try:
         import numpy as np