Squash Odysseus development history

tests/test_caldav_prune_parse_failure.py

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+"""CalDAV sync must not prune the window when it can't fully read the server.
+
+The prune deletes local caldav rows whose UID the server didn't return. `seen_uids`
+is built only from objects that parsed, so any parse failure (total or partial)
+makes it an incomplete view of the server:
+
+- total failure: `seen_uids` is empty and the prune falls back to `uid.isnot(None)`
+  (match-all), wiping every event in the window;
+- partial failure: the events that failed to parse are absent from `seen_uids`, so
+  `~uid.in_(seen_uids)` deletes those still-upstream events.
+
+`_should_prune_window` therefore only allows the prune on a clean read.
+"""
+from src.caldav_sync import _should_prune_window
+
+
+def test_prune_runs_on_clean_read():
+    # Clean read with events -> the normal ~uid.in_(seen) prune is safe.
+    assert _should_prune_window({"uid-a", "uid-b"}, parse_failed=False) is True
+
+
+def test_prune_runs_when_calendar_genuinely_empty():
+    # Clean read, no objects -> genuinely empty window -> safe to prune.
+    assert _should_prune_window(set(), parse_failed=False) is True
+
+
+def test_prune_skipped_when_all_objects_failed_to_parse():
+    # Every object failed -> empty seen_uids is "couldn't read", not "empty
+    # calendar" -> must NOT prune (would delete the whole window).
+    assert _should_prune_window(set(), parse_failed=True) is False
+
+
+def test_prune_skipped_on_partial_parse_failure():
+    # Some objects parsed and at least one failed: seen_uids is incomplete, so
+    # pruning would delete the unparsed-but-still-upstream events. Skipping the
+    # prune keeps the local copy of the unparsed event instead of deleting it.
+    assert _should_prune_window({"parsed-uid"}, parse_failed=True) is False