[utils] `traverse_obj`: More fixes (#6959)

- Fix result when branching with `traverse_string`
- Fix `slice` path on `dict`s
- Fix tests and docstrings from 21b5ec86c2c37d10c5bb97edd7051d3aac16bb3e
- Add `is_iterable_like` helper function

Authored by: Grub4K

1 files changed, 19 insertions, 2 deletions

diff --git a/test/test_utils.py b/test/test_utils.py
index f2f3b8170..e1bf6ac20 100644
--- a/test/test_utils.py
+++ b/test/test_utils.py
@@ -2016,7 +2016,7 @@ Line 1
                          msg='nested `...` queries should work')
         self.assertCountEqual(traverse_obj(_TEST_DATA, (..., ..., 'index')), range(4),
                               msg='`...` query result should be flattened')
-        self.assertEqual(traverse_obj(range(4), ...), list(range(4)),
+        self.assertEqual(traverse_obj(iter(range(4)), ...), list(range(4)),
                          msg='`...` should accept iterables')
 
         # Test function as key
@@ -2025,7 +2025,7 @@ Line 1
                          msg='function as query key should perform a filter based on (key, value)')
         self.assertCountEqual(traverse_obj(_TEST_DATA, lambda _, x: isinstance(x[0], str)), {'str'},
                               msg='exceptions in the query function should be catched')
-        self.assertEqual(traverse_obj(range(4), lambda _, x: x % 2 == 0), [0, 2],
+        self.assertEqual(traverse_obj(iter(range(4)), lambda _, x: x % 2 == 0), [0, 2],
                          msg='function key should accept iterables')
         if __debug__:
             with self.assertRaises(Exception, msg='Wrong function signature should raise in debug'):
@@ -2051,6 +2051,17 @@ Line 1
             with self.assertRaises(Exception, msg='Sets with length != 1 should raise in debug'):
                 traverse_obj(_TEST_DATA, {str.upper, str})
 
+        # Test `slice` as a key
+        _SLICE_DATA = [0, 1, 2, 3, 4]
+        self.assertEqual(traverse_obj(_TEST_DATA, ('dict', slice(1))), None,
+                         msg='slice on a dictionary should not throw')
+        self.assertEqual(traverse_obj(_SLICE_DATA, slice(1)), _SLICE_DATA[:1],
+                         msg='slice key should apply slice to sequence')
+        self.assertEqual(traverse_obj(_SLICE_DATA, slice(1, 2)), _SLICE_DATA[1:2],
+                         msg='slice key should apply slice to sequence')
+        self.assertEqual(traverse_obj(_SLICE_DATA, slice(1, 4, 2)), _SLICE_DATA[1:4:2],
+                         msg='slice key should apply slice to sequence')
+
         # Test alternative paths
         self.assertEqual(traverse_obj(_TEST_DATA, 'fail', 'str'), 'str',
                          msg='multiple `paths` should be treated as alternative paths')
@@ -2234,6 +2245,12 @@ Line 1
         self.assertEqual(traverse_obj(_TRAVERSE_STRING_DATA, ('str', (0, 2)),
                                       traverse_string=True), ['s', 'r'],
                          msg='branching should result in list if `traverse_string`')
+        self.assertEqual(traverse_obj({}, (0, ...), traverse_string=True), [],
+                         msg='branching should result in list if `traverse_string`')
+        self.assertEqual(traverse_obj({}, (0, lambda x, y: True), traverse_string=True), [],
+                         msg='branching should result in list if `traverse_string`')
+        self.assertEqual(traverse_obj({}, (0, slice(1)), traverse_string=True), [],
+                         msg='branching should result in list if `traverse_string`')
 
         # Test is_user_input behavior
         _IS_USER_INPUT_DATA = {'range8': list(range(8))}