[Storage] Fixed IndexError in azure-storage-blob-changefeed when listing directory marker blobs

sdk/storage/azure-storage-blob-changefeed/CHANGELOG.md

@@ -6,6 +6,11 @@ This version and all future versions will require Python 3.9+. Python 3.8 is no
 
 ### Features Added
 
+### Bugs Fixed
+- Fixed an `IndexError` that occurred when listing change feed events on accounts where the
+`$blobchangefeed/idx/segments/` hierarchy contains directory marker blobs (e.g.
+`idx/segments/2026/02/20`). Such non-segment paths are now skipped instead of being parsed
+as segment files.
 
 ## 12.0.0b5 (2024-04-16)
 

sdk/storage/azure-storage-blob-changefeed/azure/storage/blob/changefeed/_models.py

@@ -282,7 +282,10 @@ def _get_segment_paths(self, start_year=""):
         while not start_year or start_year <= cur_year:
             paths = self.client.list_blobs(name_starts_with=SEGMENT_COMMON_PATH + str(start_year))
             for path in paths:
-                yield path.name
+                # Skip directory marker blobs that do not conform to the expected segment path shape.
+                # Azure Storage can return zero-length directory markers that are not real segment files.
+                if self._is_valid_segment_path(path.name):
+                    yield path.name
 
             # if not searching by prefix, all paths would have been iterated already, so it"s time to yield None
             if not start_year:
@@ -291,6 +294,13 @@ def _get_segment_paths(self, start_year=""):
             start_year += 1
         yield None
 
+    @staticmethod
+    def _is_valid_segment_path(segment_path):
+        path_tokens = segment_path.split(PATH_DELIMITER)
+
+        # Expected: idx/segments/YYYY/MM/DD/HHMM/<file>
+        return len(path_tokens) >= 7 and path_tokens[6]
+
     @staticmethod
     def _parse_datetime_from_segment_path(segment_path):
         path_tokens = segment_path.split("/")

sdk/storage/azure-storage-blob-changefeed/tests/test_change_feed.py

@@ -8,6 +8,7 @@
 from datetime import datetime, timedelta
 from math import ceil
 from time import sleep
+from unittest.mock import Mock, patch
 
 import pytest
 
@@ -23,11 +24,80 @@
 # Then uncomment this import and comment out the other.
 # from changefeed import ChangeFeedClient
 from azure.storage.blob.changefeed import ChangeFeedClient
+from azure.storage.blob.changefeed._models import ChangeFeed
+
+
+def _build_change_feed(blob_names):
+    """Build a ChangeFeed backed by a mock client, skipping the network-bound _initialize()."""
+    blobs = [Mock() for _ in blob_names]
+    for blob, name in zip(blobs, blob_names):
+        blob.name = name
+    client = Mock()
+    client.list_blobs.return_value = blobs
+    with patch.object(ChangeFeed, "_initialize"):
+        return ChangeFeed(client, page_size=100)
 
 
 @pytest.mark.playback_test_only
 class TestStorageChangeFeed(StorageRecordedTestCase):
 
+    @pytest.mark.parametrize(
+        "segment_path",
+        [
+            "idx/segments/2026/02/20/0000/meta.json",
+            "idx/segments/2022/11/28/2300/meta.json",
+            "idx/segments/1601/01/01/0000/meta.json",
+        ],
+    )
+    def test_valid_segment_path_is_accepted(self, segment_path):
+        assert ChangeFeed._is_valid_segment_path(segment_path) is True
+
+    @pytest.mark.parametrize(
+        "segment_path",
+        [
+            "idx/segments/2026/02/20",        # day-level directory marker (the reported crash)
+            "idx/segments/2026/02/20/0000",   # minute-level directory marker
+            "idx/segments/2026/02",           # month-level directory marker
+            "idx/segments/2026",              # year-level directory marker
+            "idx/segments",                   # prefix only
+            "idx/segments/2026/02/20/0000/",  # trailing slash -> empty file token
+            "idx/segments/abcd/02/20/0000/meta.json",  # non-numeric year
+        ],
+    )
+    def test_directory_marker_or_malformed_path_is_rejected(self, segment_path):
+        assert ChangeFeed._is_valid_segment_path(segment_path) is False
+
+    def test_parse_datetime_from_valid_segment_path(self):
+        assert ChangeFeed._parse_datetime_from_segment_path(
+            "idx/segments/2026/02/20/0000/meta.json"
+        ) == datetime(2026, 2, 20, 0)
+
+    def test_get_segment_paths_skips_directory_markers(self):
+        blob_names = [
+            "idx/segments/2026/02/20",                 # day-level marker
+            "idx/segments/2026/02/20/0000",            # minute-level marker
+            "idx/segments/2026/02/20/0000/meta.json",  # real segment
+            "idx/segments/2026/02/20/0100/meta.json",  # real segment
+        ]
+        change_feed = _build_change_feed(blob_names)
+
+        results = list(change_feed._get_segment_paths(start_year=""))
+
+        # The generator yields a trailing None sentinel to signal "no more segments".
+        assert results[-1] is None
+        yielded_segments = [path for path in results if path is not None]
+        assert yielded_segments == [
+            "idx/segments/2026/02/20/0000/meta.json",
+            "idx/segments/2026/02/20/0100/meta.json",
+        ]
+
+    def test_get_segment_paths_does_not_raise_on_directory_markers(self):
+        blob_names = ["idx/segments/2026/02/20", "idx/segments/2026/02/20/0000/meta.json"]
+        change_feed = _build_change_feed(blob_names)
+
+        yielded_segments = [path for path in change_feed._get_segment_paths(start_year="") if path]
+        assert yielded_segments == ["idx/segments/2026/02/20/0000/meta.json"]
+
     # --Test cases for change feed -----------------------------------------
     @ChangeFeedPreparer()
     @recorded_by_proxy