From 6c1fb6b76ebba862a1c5831210ce026160da0065 Mon Sep 17 00:00:00 2001
From: Martin Durant <martin.durant@utoronto.ca>
Date: Thu, 7 Sep 2017 14:17:19 -0400
Subject: [PATCH] minimalist zarr test

---
 xarray/backends/zarr.py       |  7 ++++++-
 xarray/tests/__init__.py      |  9 ++++++++-
 xarray/tests/test_backends.py | 19 ++++++++++++++++++-
 3 files changed, 32 insertions(+), 3 deletions(-)

diff --git a/xarray/backends/zarr.py b/xarray/backends/zarr.py
index bc3be1306d2..0d33c622af2 100644
--- a/xarray/backends/zarr.py
+++ b/xarray/backends/zarr.py
@@ -76,6 +76,8 @@ class ZarrStore(AbstractWritableDataStore, DataStorePickleMixin):
 
     # need some special secret attributes to tell us the dimensions
     _dimension_key = '_XARRAY_DIMENSIONS'
+    default_arguments = dict(compressor='default', order='C', synchronizer=None,
+                             filters=None, cache_metadata=True, kwargs={})
 
     def __init__(self, store=None, overwrite=False, chunk_store=None,
                  synchronizer=None, path=None, writer=None, autoclose=False):
@@ -158,8 +160,11 @@ def prepare_variable(self, name, variable, check_encoding=False,
 
         # TODO: figure out how to pass along all those other arguments
 
+        kwargs = self.default_arguments.copy()
+        kwargs.update(kwargs.pop('kwargs'))
         zarr_array = self.ds.create(name, shape=shape, dtype=dtype,
-                                    chunks=chunks, fill_value=fill_value)
+                                    chunks=chunks, fill_value=fill_value,
+                                    **kwargs)
         zarr_array.attrs[self._dimension_key] = dims
         _, attributes = _get_zarr_dims_and_attrs(zarr_array,
                                                  self._dimension_key)
diff --git a/xarray/tests/__init__.py b/xarray/tests/__init__.py
index 424484b438a..affff9c348d 100644
--- a/xarray/tests/__init__.py
+++ b/xarray/tests/__init__.py
@@ -83,6 +83,12 @@
 except ImportError:
     has_rasterio = False
 
+try:
+    import zarr
+    has_zarr = True
+except ImportError:
+    has_zarr = False
+
 # slighly simpler construction that the full functions.
 # Generally `pytest.importorskip('package')` inline is even easier
 requires_matplotlib = pytest.mark.skipif(
@@ -105,7 +111,8 @@
     not has_bottleneck, reason='requires bottleneck')
 requires_rasterio = pytest.mark.skipif(
     not has_rasterio, reason='requires rasterio')
-
+requires_zarr = pytest.mark.skipif(
+    not has_zarr, reason='requires zarr')
 
 try:
     _SKIP_FLAKY = not pytest.config.getoption("--run-flaky")
diff --git a/xarray/tests/test_backends.py b/xarray/tests/test_backends.py
index f5bd615cfe2..9c6249f0fa3 100644
--- a/xarray/tests/test_backends.py
+++ b/xarray/tests/test_backends.py
@@ -21,13 +21,15 @@
                     open_mfdataset, backends, save_mfdataset)
 from xarray.backends.common import robust_getitem
 from xarray.backends.netCDF4_ import _extract_nc4_variable_encoding
+from xarray.backends.zarr import ZarrStore
 from xarray.core import indexing
 from xarray.core.pycompat import iteritems, PY2, ExitStack, basestring
 
 from . import (TestCase, requires_scipy, requires_netCDF4, requires_pydap,
                requires_scipy_or_netCDF4, requires_dask, requires_h5netcdf,
                requires_pynio, has_netCDF4, has_scipy, assert_allclose,
-               flaky, network, requires_rasterio, assert_identical)
+               flaky, network, requires_rasterio, assert_identical,
+               requires_zarr)
 from .test_dataset import create_test_data
 
 try:
@@ -1934,3 +1936,18 @@ def test_open_dataarray_options(self):
             expected = data.drop('y')
             with open_dataarray(tmp, drop_variables=['y']) as loaded:
                 self.assertDataArrayIdentical(expected, loaded)
+
+
+@requires_zarr
+class TestZarr(TestCase):
+
+    def test_roundtrip(self):
+        data = create_test_data()
+        del data.coords['time']
+        with create_tmp_file() as tmp:
+            z = ZarrStore(store=tmp, overwrite=True)
+            z.store_dataset(data)
+
+            z2 = open_dataset(ZarrStore(store=tmp))
+            for k in data:
+                self.assertTrue((data[k].values == z2[k].values).all())