QOL: detect both .zarr and .zarr/ as using the zarr engine (#10697)

* QOL: detect both .zarr and .zarr/ as using the zarr engine

* test: properly test the opening with a trailing slash

Author: ianhi

doc/whats-new.rst

@@ -23,6 +23,8 @@ New Features
 - ``compute=False`` is now supported by :py:meth:`DataTree.to_netcdf` and
   :py:meth:`DataTree.to_zarr`.
   By `Stephan Hoyer <https://github.com/shoyer>`_.
+- ``open_dataset`` will now correctly infer a path ending in ``.zarr/`` as zarr
+  By `Ian Hunt-Isaak <https://github.com/ianhi>`_.
 
 Breaking changes
 ~~~~~~~~~~~~~~~~

xarray/backends/zarr.py

@@ -1618,8 +1618,10 @@ class ZarrBackendEntrypoint(BackendEntrypoint):
 
     def guess_can_open(self, filename_or_obj: T_PathFileOrDataStore) -> bool:
         if isinstance(filename_or_obj, str | os.PathLike):
-            _, ext = os.path.splitext(filename_or_obj)
-            return ext == ".zarr"
+            # allow a trailing slash to account for an autocomplete
+            # adding it.
+            _, ext = os.path.splitext(str(filename_or_obj).rstrip("/"))
+            return ext in [".zarr"]
 
         return False
 

xarray/tests/test_backends.py

@@ -7149,6 +7149,31 @@ def test_h5netcdf_entrypoint(tmp_path: Path) -> None:
     assert not entrypoint.guess_can_open("not-found-and-no-extension")
 
 
+@requires_zarr
+def test_zarr_entrypoint(tmp_path: Path) -> None:
+    from xarray.backends.zarr import ZarrBackendEntrypoint
+
+    entrypoint = ZarrBackendEntrypoint()
+    ds = create_test_data()
+
+    path = tmp_path / "foo.zarr"
+    ds.to_zarr(path)
+    _check_guess_can_open_and_open(entrypoint, path, engine="zarr", expected=ds)
+    _check_guess_can_open_and_open(entrypoint, str(path), engine="zarr", expected=ds)
+
+    # add a trailing slash to the path and check again
+    _check_guess_can_open_and_open(
+        entrypoint, str(path) + "/", engine="zarr", expected=ds
+    )
+
+    # Test the new functionality: .zarr with trailing slash
+    assert entrypoint.guess_can_open("something-local.zarr")
+    assert entrypoint.guess_can_open("something-local.zarr/")  # With trailing slash
+    assert not entrypoint.guess_can_open("something-local.nc")
+    assert not entrypoint.guess_can_open("not-found-and-no-extension")
+    assert not entrypoint.guess_can_open("something.zarr.txt")
+
+
 @requires_netCDF4
 @pytest.mark.parametrize("str_type", (str, np.str_))
 def test_write_file_from_np_str(str_type: type[str | np.str_], tmpdir: str) -> None: