Fix off-by-one error in overlap_tuple

versioned_hdf5/backend.py

@@ -1323,7 +1323,7 @@ def write_to_dataset(
         written by this function.
     """
     raw_data: Dataset = f["_version_data"][name]["raw_data"]
-    chunk_size = tuple(raw_data.attrs["chunks"])[0]
+    chunk_size = raw_data.chunks[0]
 
     if isinstance(data, np.ndarray) and raw_data.dtype != data.dtype:
         raise ValueError(
@@ -1334,8 +1334,8 @@ def write_to_dataset(
     slices: Dict[Tuple, Tuple] = {}
     with Hashtable(f, name) as hashtable:
         for data_slice, vchunk in zip(
-            partition(data, chunk_size),
-            partition(virtual_slice, chunk_size),
+            partition(data, raw_data.chunks),
+            partition(virtual_slice, raw_data.chunks),
             strict=True,
         ):
             arr = data[data_slice.raw]

versioned_hdf5/slicetools.py

@@ -90,7 +90,7 @@ def overlap(index1: Slice, index2: Slice) -> Optional[Slice]:
     overlapping = Slice(max(index1.start, index2.start), min(index1.stop, index2.stop))
     # If the slices don't overlap, the start index will be greater than
     # the stop index
-    if overlapping.start > overlapping.stop:
+    if overlapping.start >= overlapping.stop:
         return None
     return overlapping
 

versioned_hdf5/tests/test_backend.py

@@ -10,6 +10,7 @@
     DEFAULT_CHUNK_SIZE,
     create_base_dataset,
     create_virtual_dataset,
+    overlap_tuple,
     write_dataset,
     write_dataset_chunks,
 )
@@ -800,3 +801,12 @@ def test_create_empty_virtual_dataset(setup_vfile):
         assert_equal(ds, np.array([]))
         assert ds.shape == (0,)
         assert ds.size == 0
+
+
+def test_overlap_tuple():
+    """Test that multidimensional indices which don't overlap have no overlap_tuple."""
+    overlapping = overlap_tuple(
+        Tuple(slice(0, 3, 1), slice(15100, 15200, 1), slice(0, 2, 1)),
+        Tuple(slice(0, 2, 1), slice(15200, 15220, 1), slice(0, 2, 1)),
+    )
+    assert overlapping is None