Skips tests if it doesn't have the correct dependency

datatree/tests/__init__.py

@@ -0,0 +1,28 @@
+import importlib
+from distutils import version
+
+import pytest
+
+
+def _importorskip(modname, minversion=None):
+    try:
+        mod = importlib.import_module(modname)
+        has = True
+        if minversion is not None:
+            if LooseVersion(mod.__version__) < LooseVersion(minversion):
+                raise ImportError("Minimum version not satisfied")
+    except ImportError:
+        has = False
+    func = pytest.mark.skipif(not has, reason=f"requires {modname}")
+    return has, func
+
+
+def LooseVersion(vstring):
+    # Our development version is something like '0.10.9+aac7bfc'
+    # This function just ignores the git commit id.
+    vstring = vstring.split("+")[0]
+    return version.LooseVersion(vstring)
+
+
+has_zarr, requires_zarr = _importorskip("zarr")
+has_netCDF4, requires_netCDF4 = _importorskip("netCDF4")

datatree/tests/test_datatree.py

@@ -5,6 +5,7 @@
 
 from datatree import DataNode, DataTree
 from datatree.io import open_datatree
+from datatree.tests import requires_netCDF4, requires_zarr
 
 
 def assert_tree_equal(dt_a, dt_b):
@@ -311,6 +312,7 @@ def test_repr_of_node_with_data(self):
 
 
 class TestIO:
+    @requires_netCDF4
     def test_to_netcdf(self, tmpdir):
         filepath = str(
             tmpdir / "test.nc"
@@ -321,6 +323,7 @@ def test_to_netcdf(self, tmpdir):
         roundtrip_dt = open_datatree(filepath)
         assert_tree_equal(original_dt, roundtrip_dt)
 
+    @requires_zarr
     def test_to_zarr(self, tmpdir):
         filepath = str(
             tmpdir / "test.zarr"

datatree/tests/test_mapping.py

@@ -1,11 +1,12 @@
 import pytest
 import xarray as xr
-from test_datatree import assert_tree_equal, create_test_datatree
 
 from datatree.datatree import DataTree
 from datatree.mapping import TreeIsomorphismError, _check_isomorphic, map_over_subtree
 from datatree.treenode import TreeNode
 
+from .test_datatree import assert_tree_equal, create_test_datatree
+
 empty = xr.Dataset()