Fix test_88_character_filename_segmentation_fault (#2026)

* Fix test_88_character_filename_segmentation_fault

This test turning all warnings into errors. Now it's more robust, and only
converts the appropriate warning into an error.

Fixes GH2025

* Fix bad git merge

Author: shoyer

xarray/backends/netCDF4_.py

@@ -264,13 +264,13 @@ def open(cls, filename, mode='r', format='NETCDF4', group=None,
         if (len(filename) == 88 and
                 LooseVersion(nc4.__version__) < "1.3.1"):
             warnings.warn(
-                '\nA segmentation fault may occur when the\n'
-                'file path has exactly 88 characters as it does\n'
-                'in this case. The issue is known to occur with\n'
-                'version 1.2.4 of netCDF4 and can be addressed by\n'
-                'upgrading netCDF4 to at least version 1.3.1.\n'
-                'More details can be found here:\n'
-                'https://github.com/pydata/xarray/issues/1745  \n')
+                'A segmentation fault may occur when the '
+                'file path has exactly 88 characters as it does '
+                'in this case. The issue is known to occur with '
+                'version 1.2.4 of netCDF4 and can be addressed by '
+                'upgrading netCDF4 to at least version 1.3.1. '
+                'More details can be found here: '
+                'https://github.com/pydata/xarray/issues/1745')
         if format is None:
             format = 'NETCDF4'
         opener = functools.partial(_open_netcdf4_group, filename, mode=mode,

xarray/tests/test_backends.py

@@ -1137,8 +1137,10 @@ def test_88_character_filename_segmentation_fault(self):
         # should be fixed in netcdf4 v1.3.1
         with mock.patch('netCDF4.__version__', '1.2.4'):
             with warnings.catch_warnings():
-                warnings.simplefilter("error")
-                with raises_regex(Warning, 'segmentation fault'):
+                message = ('A segmentation fault may occur when the '
+                           'file path has exactly 88 characters')
+                warnings.filterwarnings('error', message)
+                with pytest.raises(Warning):
                     # Need to construct 88 character filepath
                     xr.Dataset().to_netcdf('a' * (88 - len(os.getcwd()) - 1))