Fix bug with opening files using h5netcdf (#57)

* fix bug by correcting import

* add roundtripping test for h5netcdf

* add h5netcdf to CI environment

Author: TomNicholas

ci/environment.yml

@@ -11,4 +11,5 @@ dependencies:
   - black
   - codecov
   - pytest-cov
+  - h5netcdf
   - zarr

datatree/io.py

@@ -33,12 +33,12 @@ def _get_nc_dataset_class(engine):
     if engine == "netcdf4":
         from netCDF4 import Dataset
     elif engine == "h5netcdf":
-        from h5netcdf import Dataset
+        from h5netcdf.legacyapi import Dataset
     elif engine is None:
         try:
             from netCDF4 import Dataset
         except ImportError:
-            from h5netcdf import Dataset
+            from h5netcdf.legacyapi import Dataset
     else:
         raise ValueError(f"unsupported engine: {engine}")
     return Dataset

datatree/tests/__init__.py

@@ -25,4 +25,5 @@ def LooseVersion(vstring):
 
 
 has_zarr, requires_zarr = _importorskip("zarr")
+has_h5netcdf, requires_h5netcdf = _importorskip("h5netcdf")
 has_netCDF4, requires_netCDF4 = _importorskip("netCDF4")

datatree/tests/test_datatree.py

@@ -6,7 +6,7 @@
 from datatree import DataTree
 from datatree.io import open_datatree
 from datatree.testing import assert_equal
-from datatree.tests import requires_netCDF4, requires_zarr
+from datatree.tests import requires_h5netcdf, requires_netCDF4, requires_zarr
 
 
 def create_test_datatree(modify=lambda ds: ds):
@@ -340,6 +340,17 @@ def test_to_netcdf(self, tmpdir):
         roundtrip_dt = open_datatree(filepath)
         assert_equal(original_dt, roundtrip_dt)
 
+    @requires_h5netcdf
+    def test_to_h5netcdf(self, tmpdir):
+        filepath = str(
+            tmpdir / "test.nc"
+        )  # casting to str avoids a pathlib bug in xarray
+        original_dt = create_test_datatree()
+        original_dt.to_netcdf(filepath, engine="h5netcdf")
+
+        roundtrip_dt = open_datatree(filepath)
+        assert_equal(original_dt, roundtrip_dt)
+
     @requires_zarr
     def test_to_zarr(self, tmpdir):
         filepath = str(