sorts: type bubble sort for any comparable items

Bound bubble_sort_iterative and bubble_sort_recursive to a Comparable protocol instead of Any, add TypeError doctests, and cover the mixed-type failure in tests/test_sorts.py.

Refs #15234

Author: Harsh Raj Singhania

sorts/bubble_sort.py

@@ -1,7 +1,14 @@
-from typing import Any
+from typing import Any, Protocol, TypeVar
 
 
-def bubble_sort_iterative(collection: list[Any]) -> list[Any]:
+class Comparable(Protocol):
+    def __lt__(self, other: Any, /) -> bool: ...
+
+
+T = TypeVar("T", bound=Comparable)
+
+
+def bubble_sort_iterative[T: Comparable](collection: list[T]) -> list[T]:
     """Pure implementation of the bubble sort algorithm in Python (iterative).
 
     Bubble sort works by repeatedly stepping through the collection,
@@ -58,6 +65,10 @@ def bubble_sort_iterative(collection: list[Any]) -> list[Any]:
     >>> collection_arg = random.choices(string.ascii_letters + string.digits, k=100)
     >>> bubble_sort_iterative(collection_arg) == sorted(collection_arg)
     True
+    >>> bubble_sort_iterative([1, "a"])  # doctest: +IGNORE_EXCEPTION_DETAIL
+    Traceback (most recent call last):
+        ...
+    TypeError: '<' not supported between instances of 'str' and 'int'
     """
     length = len(collection)
     for i in reversed(range(length)):
@@ -71,7 +82,7 @@ def bubble_sort_iterative(collection: list[Any]) -> list[Any]:
     return collection
 
 
-def bubble_sort_recursive(collection: list[Any]) -> list[Any]:
+def bubble_sort_recursive[T: Comparable](collection: list[T]) -> list[T]:
     """Pure implementation of the bubble sort algorithm in Python (recursive).
 
     Functionally identical to the iterative version: each call makes a
@@ -124,6 +135,10 @@ def bubble_sort_recursive(collection: list[Any]) -> list[Any]:
     >>> collection_arg = random.choices(string.ascii_letters + string.digits, k=100)
     >>> bubble_sort_recursive(collection_arg) == sorted(collection_arg)
     True
+    >>> bubble_sort_recursive([1, "a"])  # doctest: +IGNORE_EXCEPTION_DETAIL
+    Traceback (most recent call last):
+        ...
+    TypeError: '<' not supported between instances of 'str' and 'int'
     """
     length = len(collection)
     swapped = False

tests/test_sorts.py

@@ -17,7 +17,7 @@
 import pytest
 
 from sorts.binary_insertion_sort import binary_insertion_sort
-from sorts.bubble_sort import bubble_sort_iterative
+from sorts.bubble_sort import bubble_sort_iterative, bubble_sort_recursive
 from sorts.circle_sort import circle_sort
 from sorts.cocktail_shaker_sort import cocktail_shaker_sort
 from sorts.comb_sort import comb_sort
@@ -92,3 +92,13 @@ def test_sort_matches_builtin(sort, case):
 def test_binary_insertion_sort_rejects_non_comparable_items():
     with pytest.raises(TypeError):
         binary_insertion_sort([1, "a"])
+
+
+@pytest.mark.parametrize(
+    "sort",
+    (bubble_sort_iterative, bubble_sort_recursive),
+    ids=lambda f: f.__name__,
+)
+def test_bubble_sort_rejects_non_comparable_items(sort):
+    with pytest.raises(TypeError):
+        sort([1, "a"])