TST/COMPAT: Catch warnings for new pytest (dask#2370)

Compat for newer pandas moving is_datetime64tz import

Author: TomAugspurger

dask/dataframe/io/tests/test_csv.py

@@ -422,23 +422,26 @@ def test_read_csv_compression(fmt, blocksize):
                   expected.reset_index(drop=True), check_dtype=False)
 
 
-def test_warn_non_seekable_files(capsys):
+def test_warn_non_seekable_files():
     files2 = valmap(compress['gzip'], csv_files)
     with filetexts(files2, mode='b'):
 
-        # with tm.assert_produces_warning(UserWarning):
-        df = dd.read_csv('2014-01-*.csv', compression='gzip')
-        assert df.npartitions == 3
-        out, err = capsys.readouterr()
-        assert 'gzip' in err
-        assert 'blocksize=None' in err
+        with pytest.warns(UserWarning) as w:
+            df = dd.read_csv('2014-01-*.csv', compression='gzip')
+            assert df.npartitions == 3
 
-        df = dd.read_csv('2014-01-*.csv', compression='gzip', blocksize=None)
-        out, err = capsys.readouterr()
-        assert not err and not out
+        assert len(w) == 1
+        msg = str(w[0].message)
+        assert 'gzip' in msg
+        assert 'blocksize=None' in msg
+
+        with pytest.warns(None) as w:
+            df = dd.read_csv('2014-01-*.csv', compression='gzip', blocksize=None)
+        assert len(w) == 0
 
         with pytest.raises(NotImplementedError):
-            df = dd.read_csv('2014-01-*.csv', compression='foo')
+            with pytest.warns(None):
+                df = dd.read_csv('2014-01-*.csv', compression='foo')
 
 
 def test_windows_line_terminator():

dask/dataframe/tests/test_categorical.py

@@ -1,5 +1,4 @@
 import operator
-import warnings
 
 import numpy as np
 import pandas as pd
@@ -234,7 +233,7 @@ def test_categorical_accessor_presence():
 def test_categorize_nan():
     df = dd.from_pandas(pd.DataFrame({"A": ['a', 'b', 'a', float('nan')]}),
                         npartitions=2)
-    with warnings.catch_warnings(record=True) as record:
+    with pytest.warns(None) as record:
         df.categorize().compute()
     assert len(record) == 0
 

dask/dataframe/utils.py

@@ -12,8 +12,12 @@
 import numpy as np
 import pandas as pd
 import pandas.util.testing as tm
-from pandas.core.common import is_datetime64tz_dtype
 from pandas.api.types import is_categorical_dtype, is_scalar
+try:
+    from pandas.api.types import is_datetime64tz_dtype
+except ImportError:
+    # pandas < 0.19.2
+    from pandas.core.common import is_datetime64tz_dtype
 
 from ..core import get_deps
 from ..local import get_sync