fix unintentional skipped tests (#1557)

* move requires_pynio to fix GH1531, refactor tests/__init__.py

* remove ModuleNotFoundError

* no pytest decorators on classes with multiple inheritance in test_backends.py

* wrap class decorators for tests

* no more class decorators in test_backends

* whats new and some more cleanup

* whatsnew update

* use unittest skip decorators, way easier

* update workaround comment

Author: Joe Hamman

doc/whats-new.rst

@@ -54,9 +54,9 @@ Breaking changes
     [...]
 
   Note that both versions are currently supported, but using the old syntax will
-  produce a warning encouraging users to adopt the new syntax. 
+  produce a warning encouraging users to adopt the new syntax.
   By `Daniel Rothenberg <https://github.com/darothen>`_.
-  
+
 - ``repr`` and the Jupyter Notebook won't automatically compute dask variables.
   Datasets loaded with ``open_dataset`` won't automatically read coords from
   disk when calling ``repr`` (:issue:`1522`).
@@ -212,6 +212,10 @@ Bug fixes
   the first argument was a numpy variable (:issue:`1588`).
   By `Guido Imperiale <https://github.com/crusaderky>`_.
 
+- Fix bug when using ``pytest`` class decorators to skiping certain unittests.
+  The previous behavior unintentionally causing additional tests to be skipped
+  (:issue:`1531`). By `Joe Hamman <https://github.com/jhamman>`_.
+
 .. _whats-new.0.9.6:
 
 v0.9.6 (8 June 2017)

xarray/tests/__init__.py

@@ -5,6 +5,7 @@
 from contextlib import contextmanager
 from distutils.version import LooseVersion
 import re
+import importlib
 
 import numpy as np
 from numpy.testing import assert_array_equal
@@ -25,111 +26,50 @@
 except ImportError:
     import mock
 
-try:
-    import scipy
-    has_scipy = True
-except ImportError:
-    has_scipy = False
-
-try:
-    import pydap.client
-    has_pydap = True
-except ImportError:
-    has_pydap = False
-
-try:
-    import netCDF4
-    has_netCDF4 = True
-except ImportError:
-    has_netCDF4 = False
-
-
-try:
-    import h5netcdf
-    has_h5netcdf = True
-except ImportError:
-    has_h5netcdf = False
-
-
-try:
-    import Nio
-    has_pynio = True
-except ImportError:
-    has_pynio = False
-
-
-try:
-    import dask.array
-    import dask
-    dask.set_options(get=dask.get)
-    has_dask = True
-except ImportError:
-    has_dask = False
-
-
-try:
-    import matplotlib
-    has_matplotlib = True
-except ImportError:
-    has_matplotlib = False
-
 
-try:
-    import bottleneck
-    if LooseVersion(bottleneck.__version__) < LooseVersion('1.1'):
-        raise ImportError('Fall back to numpy')
-    has_bottleneck = True
-except ImportError:
-    has_bottleneck = False
-
-try:
-    import rasterio
-    has_rasterio = True
-except ImportError:
-    has_rasterio = False
-
-try:
-    import pathlib
-    has_pathlib = True
-except ImportError:
+def _importorskip(modname, minversion=None):
     try:
-        import pathlib2
-        has_pathlib = True
+        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_pathlib = False
-
-
-# slighly simpler construction that the full functions.
-# Generally `pytest.importorskip('package')` inline is even easier
-requires_matplotlib = pytest.mark.skipif(
-    not has_matplotlib, reason='requires matplotlib')
-requires_scipy = pytest.mark.skipif(
-    not has_scipy, reason='requires scipy')
-requires_pydap = pytest.mark.skipif(
-    not has_pydap, reason='requires pydap')
-requires_netCDF4 = pytest.mark.skipif(
-    not has_netCDF4, reason='requires netCDF4')
-requires_h5netcdf = pytest.mark.skipif(
-    not has_h5netcdf, reason='requires h5netcdf')
-requires_pynio = pytest.mark.skipif(
-    not has_pynio, reason='requires pynio')
-requires_scipy_or_netCDF4 = pytest.mark.skipif(
-    not has_scipy and not has_netCDF4, reason='requires scipy or netCDF4')
-requires_dask = pytest.mark.skipif(
-    not has_dask, reason='requires dask')
-requires_bottleneck = pytest.mark.skipif(
-    not has_bottleneck, reason='requires bottleneck')
-requires_rasterio = pytest.mark.skipif(
-    not has_rasterio, reason='requires rasterio')
-requires_pathlib = pytest.mark.skipif(
-    not has_pathlib, reason='requires pathlib / pathlib2'
-)
-
+        has = False
+    # TODO: use pytest.skipif instead of unittest.skipUnless
+    # Using `unittest.skipUnless` is a temporary workaround for pytest#568,
+    # wherein class decorators stain inherited classes.
+    # xref: xarray#1531, implemented in xarray #1557.
+    func = unittest.skipUnless(has, reason='requires {}'.format(modname))
+    return has, func
+
+
+has_matplotlib, requires_matplotlib = _importorskip('matplotlib')
+has_scipy, requires_scipy = _importorskip('scipy')
+has_pydap, requires_pydap = _importorskip('pydap.client')
+has_netCDF4, requires_netCDF4 = _importorskip('netCDF4')
+has_h5netcdf, requires_h5netcdf = _importorskip('h5netcdf')
+has_pynio, requires_pynio = _importorskip('pynio')
+has_dask, requires_dask = _importorskip('dask')
+has_bottleneck, requires_bottleneck = _importorskip('bottleneck')
+has_rasterio, requires_rasterio = _importorskip('rasterio')
+has_pathlib, requires_pathlib = _importorskip('pathlib')
+
+# some special cases
+has_scipy_or_netCDF4 = has_scipy or has_netCDF4
+requires_scipy_or_netCDF4 = unittest.skipUnless(
+    has_scipy_or_netCDF4, reason='requires scipy or netCDF4')
+if not has_pathlib:
+    has_pathlib, requires_pathlib = _importorskip('pathlib2')
+
+if has_dask:
+    import dask
+    dask.set_options(get=dask.get)
 
 try:
     _SKIP_FLAKY = not pytest.config.getoption("--run-flaky")
     _SKIP_NETWORK_TESTS = not pytest.config.getoption("--run-network-tests")
-except ValueError:
+except (ValueError, AttributeError):
     # Can't get config from pytest, e.g., because xarray is installed instead
     # of being run from a development version (and hence conftests.py is not
     # available). Don't run flaky tests.

xarray/tests/test_backends.py

@@ -1179,7 +1179,7 @@ def test_encoding_unlimited_dims(self):
 
 
 # tests pending h5netcdf fix
-@pytest.mark.xfail
+@unittest.skip
 class H5NetCDFDataTestAutocloseTrue(H5NetCDFDataTest):
     autoclose = True