MutaFix run: more-itertools-005

ranker nvidia/NVIDIA-Nemotron-3-Nano-30B-A3B · patcher nvidia/nemotron-3-super-120b-a12b · via Nebius Token Factory

fixedoutcome
36swall time
2model calls
$0.0008API cost
Benchmark ground truth (hidden from the agent)
more_itertools/more.py:3600 · operator CONST · function more_itertools/more.py::set_partitions.<locals>.set_partitions_helper
- yield p[:i] + [[e] + p[i]] + p[i + 2 :]   (injected bug)+ yield p[:i] + [[e] + p[i]] + p[i + 1 :]   (original)
retriever rank 1 of 20 · ranker position 1 · patched the right function yes · exact restore yes

Trace

reproduce
+12.48s
5 failing test(s) · 5 failed, 763 passed · 12.48s
failing tests and errors
tests/test_more.py::SetPartitionsTests::test_each_correct
tests/test_more.py::SetPartitionsTests::test_found_all
tests/test_more.py::SetPartitionsTests::test_max_size
tests/test_more.py::SetPartitionsTests::test_min_size
tests/test_more.py::SetPartitionsTests::test_stirling_numbers
tests/test_more.py::SetPartitionsTests::test_each_correct
E   AssertionError: Items in the first set but not the second:
E   2
E   3
E   4
E   5
tests/test_more.py::SetPartitionsTests::test_found_all
E   AssertionError: Froze[26 chars]([0, 4], FrozenSet([1, 2], FrozenSet([3]], Fro[1503 chars][0]]] != Froze[26 chars]([0, 1], FrozenSet([3, 4]], FrozenSet([FrozenS[960 chars][0]]]
trace
+18.46s
re-ran 1 test file(s) with the trace plugin: 5 failing and 615 passing tests, 2 library functions ran in a failing test · 5.9s
tests/test_more.py
retrieve
+18.46s
280 functions indexed, 2 reachable from tests/test_more.py::SetPartitionsTests::test_each_correct in the static call graph. Kept 20 candidates, ranked by spectrum score (Ochiai), call graph and BM25 break ties.
candidates in retriever order
  1. more_itertools/more.py::set_partitions.<locals>.set_partitions_helper call depth 1 · Ochiai 0.84 (failing 5, passing 2)
  2. more_itertools/more.py::set_partitions call depth 1 · Ochiai 0.71 (failing 5, passing 5)
  3. more_itertools/recipes.py::all_equal call depth - · Ochiai 0.00 (failing 0, passing 12)
  4. more_itertools/more.py::only call depth - · Ochiai 0.00 (failing 0, passing 6)
  5. more_itertools/more.py::distinct_permutations call depth - · Ochiai 0.00 (failing 0, passing 7)
  6. more_itertools/more.py::mark_ends call depth - · Ochiai 0.00 (failing 0, passing 1)
  7. more_itertools/more.py::one call depth - · Ochiai 0.00 (failing 0, passing 6)
  8. more_itertools/more.py::windowed_complete call depth - · Ochiai 0.00 (failing 0, passing 4)
  9. more_itertools/more.py::all_unique call depth - · Ochiai 0.00 (failing 0, passing 5)
  10. more_itertools/more.py::is_sorted call depth - · Ochiai 0.00 (failing 0, passing 1)
  11. more_itertools/more.py::iequals call depth - · Ochiai 0.00 (failing 0, passing 9)
  12. more_itertools/more.py::substrings_indexes call depth - · Ochiai 0.00 (failing 0, passing 5)
  13. more_itertools/more.py::substrings call depth - · Ochiai 0.00 (failing 0, passing 4)
  14. more_itertools/more.py::partitions call depth - · Ochiai 0.00 (failing 0, passing 4)
  15. more_itertools/more.py::spy call depth - · Ochiai 0.00 (failing 0, passing 10)
  16. more_itertools/more.py::unzip call depth - · Ochiai 0.00 (failing 0, passing 5)
  17. more_itertools/more.py::make_decorator call depth - · Ochiai 0.00 (failing 0, passing 3)
  18. more_itertools/more.py::classify_unique call depth - · Ochiai 0.00 (failing 0, passing 14)
  19. more_itertools/more.py::numeric_range._index_near call depth - · Ochiai 0.00 (failing 0, passing 5)
  20. more_itertools/recipes.py::partition call depth - · Ochiai 0.00 (failing 0, passing 0)
rank
+18.46s
spectrum order kept (no model call)
  1. more_itertools/more.py::set_partitions.<locals>.set_partitions_helper
  2. more_itertools/more.py::set_partitions
  3. more_itertools/recipes.py::all_equal
  4. more_itertools/more.py::only
  5. more_itertools/more.py::distinct_permutations
read
+21.08s
turn 1 · NVIDIA-Nemotron-3-Nano-30B-A3B · 5501 in / 129 out · 2.62s · $0.00036

read more_itertools/more.py::set_partitions.<locals>.set_partitions_helper

The failing tests show that set_partitions is producing incorrect partitions. The helper function set_partitions_helper (candidate 1) is responsible for generating partitions recursively. The bug is likely in how it constructs new partitions when adding an element to existing partitions. Specifically, line 3600 uses `p[i + 2 :]` which incorrectly skips an element when slicing the partition list. This would cause elements to be misplaced or omitted in the generated partitions, leading to the assertion failures seen in the tests.

patch
+36.44s
turn 2 · NVIDIA-Nemotron-3-Nano-30B-A3B · 5879 in / 215 out · 2.44s · $0.00040

The bug is in line 3600 of the set_partitions_helper function. When adding the element `e` to each existing partition `p`, the code incorrectly slices the list using `p[i + 2:]` which skips one element ahead, causing elements to be omitted from the resulting partition. This leads to incorrect set partitions being generated, which explains the assertion failures in the tests. The correct slice should be `p[i + 1:]` to properly include all remaining elements after inserting the new partition containing `e` at position `i`.

--- a/more_itertools/more.py+++ b/more_itertools/more.py@@ -3598,5 +3598,5 @@             for p in set_partitions_helper(M, k):                 for i in range(len(p)):-                    yield p[:i] + [[e] + p[i]] + p[i + 2 :]+                    yield p[:i] + [[e] + p[i]] + p[i + 1 :]      if k is None:

tests: all tests pass 768 passed

Final patch

--- a/more_itertools/more.py+++ b/more_itertools/more.py@@ -3598,5 +3598,5 @@             for p in set_partitions_helper(M, k):                 for i in range(len(p)):-                    yield p[:i] + [[e] + p[i]] + p[i + 2 :]+                    yield p[:i] + [[e] + p[i]] + p[i + 1 :]      if k is None: