utils.grouper: Improve implementation

Loader-tar defines a slightly different utils.grouper to deal with iterable of tuples. This improves the generic definition to deal with that case. That allows to remove some code in the loader-tar.

Related swh-environment#1411 (closed)

Test Plan

tox

---

Migrated from D793 (view on Phabricator)

swh/core/tests/test_utils.py

-# Copyright (C) 2015-2017  The Software Heritage developers
+# Copyright (C) 2015-2018  The Software Heritage developers
 # See the AUTHORS file at the top-level directory of this distribution
 # License: GNU General Public License version 3, or any later version
 # See top-level LICENSE file for more information
@@ -29,6 +29,30 @@ class UtilsLib(unittest.TestCase):
 
         self.assertEqual(out, [[9, 8, 7, 6], [5, 4, 3, 2], [1]])
 
+    def test_grouper_with_stop_value(self):
+        # given
+        actual_data = utils.grouper(((i, i+1) for i in range(0, 9)), 2)
+
+        out = []
+        for d in actual_data:
+            out.append(list(d))  # force generator resolution for checks
+
+        self.assertEqual(out, [
+            [(0, 1), (1, 2)],
+            [(2, 3), (3, 4)],
+            [(4, 5), (5, 6)],
+            [(6, 7), (7, 8)],
+            [(8, 9)]])
+
+        # given
+        actual_data = utils.grouper((i for i in range(9, 0, -1)), 4)
+
+        out = []
+        for d in actual_data:
+            out.append(list(d))  # force generator resolution for checks
+
+        self.assertEqual(out, [[9, 8, 7, 6], [5, 4, 3, 2], [1]])
+
     def test_backslashescape_errors(self):
         raw_data_err = b'abcd\x80'
         with self.assertRaises(UnicodeDecodeError):

[vlorentz]

That line should be [(8, 9), (None, None)]

[Antoine R. Dumont]

According to the wrong docstring (because incomplete), you are correct!