explicitly checks buffersize's type and add test_map_buffersize_type_validation

Author: ebonnal

Lib/concurrent/futures/_base.py

@@ -600,6 +600,8 @@ def map(self, fn, *iterables, timeout=None, chunksize=1, buffersize=None):
                 before the given timeout.
             Exception: If fn(*args) raises for any values.
         """
+        if buffersize is not None and not isinstance(buffersize, int):
+            raise TypeError("buffersize must be an integer or None")
         if buffersize is not None and buffersize < 1:
             raise ValueError("buffersize must be None or > 0")
 

Lib/test/test_concurrent_futures/executor.py

@@ -73,7 +73,16 @@ def test_map_timeout(self):
 
         self.assertEqual([None, None], results)
 
-    def test_map_buffersize_validation(self):
+    def test_map_buffersize_type_validation(self):
+        for buffersize in ("foo", 2.0):
+            with self.subTest(buffersize=buffersize):
+                with self.assertRaisesRegex(
+                    TypeError,
+                    "buffersize must be an integer or None",
+                ):
+                    self.executor.map(str, range(4), buffersize=buffersize)
+
+    def test_map_buffersize_value_validation(self):
         for buffersize in (0, -1):
             with self.subTest(buffersize=buffersize):
                 with self.assertRaisesRegex(