Report, if target parent directory does not exist

Author: forman

CHANGES.md

@@ -1,5 +1,11 @@
 ## Version 0.4.1 (in development)
 
+### Fixes
+
+* If the target _parent_ directory did not exist, an exception was raised 
+  reporting that the lock file to be written does not exist. Changed this to
+  report that the target parent directory does not exist. [#55]
+
 ## Version 0.4.0 (from 2024-02-08)
 
 ### Enhancements

tests/test_api.py

@@ -55,6 +55,21 @@ def test_some_slices_local(self):
             for slice_dir in slices:
                 shutil.rmtree(slice_dir, ignore_errors=True)
 
+    def test_some_slices_local_output_to_non_existing_dir(self):
+        target_dir = "non_existent_dir/target.zarr"
+        slices = [
+            "slice-1.zarr",
+            "slice-2.zarr",
+            "slice-3.zarr",
+        ]
+        for uri in slices:
+            make_test_dataset(uri=uri)
+        with pytest.raises(
+            FileNotFoundError,
+            match="\\ATarget parent directory does not exist: .*/non_existent_dir\\Z",
+        ):
+            zappend(slices, target_dir=target_dir)
+
     def test_some_slices_with_class_slice_source(self):
         target_dir = "memory://target.zarr"
         slices = [make_test_dataset(), make_test_dataset(), make_test_dataset()]

zappend/fsutil/transaction.py

@@ -115,6 +115,12 @@ def __enter__(self):
             )
         self._entered_ctx = True
 
+        if not self.target_dir.parent.exists():
+            raise FileNotFoundError(
+                f"Target parent directory does not exist:"
+                f" {self.target_dir.parent.path}"
+            )
+
         lock_file = self._lock_file
         if lock_file.exists():
             raise OSError(f"Target is locked: {lock_file.uri}")