format: chunk grids with a zero extent have no chunks (no division by zero)

A Fixed or Extensible Array index whose maximum extent (the current one when no maximum is recorded) is 0 along a dimension has a zero stride for every dimension before it; ChunkGrid::offsets divided by it. The unfixed editor made such files by resizing a clawhdf5-written dataset to a zero extent: `h5rs check` panicked and the next resize raised an internal error (12 of the reviewer's random-edit seeds 10..39). Such an index has no slot for any chunk of the dataset; offsets now returns None. Tests: chunk_grid::zero_extent_has_no_chunks; edit_interop's zero_extent_resizes_without_a_recorded_maximum on a file the unfixed editor left (fixture) and on a 2.7.0-written file taken through zero extents with `h5rs check --data` and h5dump at every step; test_edit.py random edits on seeds 10..39 of a clawhdf5-written file. Co-Authored-By: Claude Opus 5.5 (1M context) <[email protected]>
2026-09-27 07:40:11 -05:00
parent 1f7651644b
commit bdf584abb2
5 changed files with 116 additions and 0 deletions
@@ -445,6 +445,13 @@ def test_random_edits_match_h5py(h5py, tmp_path, source, seed):
    h5dump_reads(ours_path, base)


+@pytest.mark.parametrize("seed", range(10, 40))
+def test_random_edits_on_clawhdf5_files(h5py, tmp_path, seed):
+    """More random sequences on a clawhdf5-written file, whose resizes to
+    zero extents once left files `h5rs check` could not read."""
+    test_random_edits_match_h5py(h5py, tmp_path, "clawhdf5", seed)
+
+
 def resized_model(before, shape, fill):
    """`before` resized to `shape` as HDF5 resizes: elements inside both
    extents keep their values, the others read as the fill value."""