MAINT: Clean up pandas/util/testing.py (#16271)

Transform testing methods to use more
pytest idiom.

Also, assume that dateutil and pytz
are installed for testing because
there are core dependencies for pandas.

pandas/tests/groupby/test_timegrouper.py

@@ -1,6 +1,7 @@
 """ test with the TimeGrouper / grouping with datetimes """
 
 import pytest
+import pytz
 
 from datetime import datetime
 import numpy as np
@@ -569,10 +570,8 @@ def test_groupby_with_timezone_selection(self):
         tm.assert_series_equal(df1, df2)
 
     def test_timezone_info(self):
-        # GH 11682
-        # Timezone info lost when broadcasting scalar datetime to DataFrame
-        tm._skip_if_no_pytz()
-        import pytz
+        # see gh-11682: Timezone info lost when broadcasting
+        # scalar datetime to DataFrame
 
         df = pd.DataFrame({'a': [1], 'b': [datetime.now(pytz.utc)]})
         assert df['b'][0].tzinfo == pytz.utc

pandas/tests/indexes/datetimes/test_astype.py

@@ -1,8 +1,12 @@
 import pytest
 
+import pytz
+import dateutil
 import numpy as np
 
 from datetime import datetime
+from dateutil.tz import tzlocal
+
 import pandas as pd
 import pandas.util.testing as tm
 from pandas import (DatetimeIndex, date_range, Series, NaT, Index, Timestamp,
@@ -124,8 +128,6 @@ def test_astype_raises(self):
         pytest.raises(ValueError, idx.astype, 'datetime64[D]')
 
     def test_index_convert_to_datetime_array(self):
-        tm._skip_if_no_pytz()
-
         def _check_rng(rng):
             converted = rng.to_pydatetime()
             assert isinstance(converted, np.ndarray)
@@ -143,9 +145,6 @@ def _check_rng(rng):
         _check_rng(rng_utc)
 
     def test_index_convert_to_datetime_array_explicit_pytz(self):
-        tm._skip_if_no_pytz()
-        import pytz
-
         def _check_rng(rng):
             converted = rng.to_pydatetime()
             assert isinstance(converted, np.ndarray)
@@ -164,9 +163,6 @@ def _check_rng(rng):
         _check_rng(rng_utc)
 
     def test_index_convert_to_datetime_array_dateutil(self):
-        tm._skip_if_no_dateutil()
-        import dateutil
-
         def _check_rng(rng):
             converted = rng.to_pydatetime()
             assert isinstance(converted, np.ndarray)
@@ -209,8 +205,6 @@ def test_to_period_microsecond(self):
         assert period[1] == Period('2007-01-01 10:11:13.789123Z', 'U')
 
     def test_to_period_tz_pytz(self):
-        tm._skip_if_no_pytz()
-        from dateutil.tz import tzlocal
         from pytz import utc as UTC
 
         xp = date_range('1/1/2000', '4/1/2000').to_period()
@@ -240,10 +234,6 @@ def test_to_period_tz_pytz(self):
         tm.assert_index_equal(ts.to_period(), xp)
 
     def test_to_period_tz_explicit_pytz(self):
-        tm._skip_if_no_pytz()
-        import pytz
-        from dateutil.tz import tzlocal
-
         xp = date_range('1/1/2000', '4/1/2000').to_period()
 
         ts = date_range('1/1/2000', '4/1/2000', tz=pytz.timezone('US/Eastern'))
@@ -271,10 +261,6 @@ def test_to_period_tz_explicit_pytz(self):
         tm.assert_index_equal(ts.to_period(), xp)
 
     def test_to_period_tz_dateutil(self):
-        tm._skip_if_no_dateutil()
-        import dateutil
-        from dateutil.tz import tzlocal
-
         xp = date_range('1/1/2000', '4/1/2000').to_period()
 
         ts = date_range('1/1/2000', '4/1/2000', tz='dateutil/US/Eastern')

pandas/tests/indexes/datetimes/test_construction.py

@@ -1,5 +1,6 @@
 import pytest
 
+import pytz
 import numpy as np
 from datetime import timedelta
 
@@ -350,10 +351,7 @@ def test_constructor_coverage(self):
         pytest.raises(ValueError, DatetimeIndex, periods=10, freq='D')
 
     def test_constructor_datetime64_tzformat(self):
-        # GH 6572
-        tm._skip_if_no_pytz()
-        import pytz
-        # ISO 8601 format results in pytz.FixedOffset
+        # see gh-6572: ISO 8601 format results in pytz.FixedOffset
         for freq in ['AS', 'W-SUN']:
             idx = date_range('2013-01-01T00:00:00-05:00',
                              '2016-01-01T23:59:59-05:00', freq=freq)
@@ -376,8 +374,6 @@ def test_constructor_datetime64_tzformat(self):
                                      tz='Asia/Tokyo')
             tm.assert_numpy_array_equal(idx.asi8, expected_i8.asi8)
 
-        tm._skip_if_no_dateutil()
-
         # Non ISO 8601 format results in dateutil.tz.tzoffset
         for freq in ['AS', 'W-SUN']:
             idx = date_range('2013/1/1 0:00:00-5:00', '2016/1/1 23:59:59-5:00',

pandas/tests/indexes/datetimes/test_date_range.py

@@ -6,6 +6,7 @@
 import pytest
 
 import numpy as np
+from pytz import timezone
 from datetime import datetime, timedelta, time
 
 import pandas as pd
@@ -299,10 +300,7 @@ def test_range_bug(self):
         tm.assert_index_equal(result, DatetimeIndex(exp_values))
 
     def test_range_tz_pytz(self):
-        # GH 2906
-        tm._skip_if_no_pytz()
-        from pytz import timezone
-
+        # see gh-2906
         tz = timezone('US/Eastern')
         start = tz.localize(datetime(2011, 1, 1))
         end = tz.localize(datetime(2011, 1, 3))
@@ -323,9 +321,6 @@ def test_range_tz_pytz(self):
         assert dr[2] == end
 
     def test_range_tz_dst_straddle_pytz(self):
-
-        tm._skip_if_no_pytz()
-        from pytz import timezone
         tz = timezone('US/Eastern')
         dates = [(tz.localize(datetime(2014, 3, 6)),
                   tz.localize(datetime(2014, 3, 12))),
@@ -349,8 +344,8 @@ def test_range_tz_dst_straddle_pytz(self):
             assert np.all(dr.hour == 0)
 
     def test_range_tz_dateutil(self):
-        # GH 2906
-        tm._skip_if_no_dateutil()
+        # see gh-2906
+
         # Use maybe_get_tz to fix filename in tz under dateutil.
         from pandas._libs.tslib import maybe_get_tz
         tz = lambda x: maybe_get_tz('dateutil/' + x)

pandas/tests/indexes/datetimes/test_datetime.py

@@ -3,6 +3,7 @@
 import numpy as np
 from datetime import date, timedelta, time
 
+import dateutil
 import pandas as pd
 import pandas.util.testing as tm
 from pandas.compat import lrange
@@ -363,11 +364,7 @@ def test_map(self):
         tm.assert_index_equal(result, exp)
 
     def test_iteration_preserves_tz(self):
-
-        tm._skip_if_no_dateutil()
-
-        # GH 8890
-        import dateutil
+        # see gh-8890
         index = date_range("2012-01-01", periods=3, freq='H', tz='US/Eastern')
 
         for i, ts in enumerate(index):

pandas/tests/indexes/datetimes/test_indexing.py

@@ -1,5 +1,6 @@
 import pytest
 
+import pytz
 import numpy as np
 import pandas as pd
 import pandas.util.testing as tm
@@ -97,10 +98,7 @@ def test_insert(self):
         assert result.name == expected.name
         assert result.freq is None
 
-        # GH 7299
-        tm._skip_if_no_pytz()
-        import pytz
-
+        # see gh-7299
         idx = date_range('1/1/2000', periods=3, freq='D', tz='Asia/Tokyo',
                          name='idx')
         with pytest.raises(ValueError):

pandas/tests/indexes/datetimes/test_ops.py

@@ -1,4 +1,6 @@
+import pytz
 import pytest
+import dateutil
 import warnings
 import numpy as np
 from datetime import timedelta
@@ -1177,13 +1179,9 @@ def test_summary(self):
         self.rng[2:2].summary()
 
     def test_summary_pytz(self):
-        tm._skip_if_no_pytz()
-        import pytz
         bdate_range('1/1/2005', '1/1/2009', tz=pytz.utc).summary()
 
     def test_summary_dateutil(self):
-        tm._skip_if_no_dateutil()
-        import dateutil
         bdate_range('1/1/2005', '1/1/2009', tz=dateutil.tz.tzutc()).summary()
 
     def test_equals(self):
@@ -1279,13 +1277,9 @@ def test_summary(self):
         self.rng[2:2].summary()
 
     def test_summary_pytz(self):
-        tm._skip_if_no_pytz()
-        import pytz
         cdate_range('1/1/2005', '1/1/2009', tz=pytz.utc).summary()
 
     def test_summary_dateutil(self):
-        tm._skip_if_no_dateutil()
-        import dateutil
         cdate_range('1/1/2005', '1/1/2009', tz=dateutil.tz.tzutc()).summary()
 
     def test_equals(self):

pandas/tests/indexes/datetimes/test_setops.py

@@ -306,7 +306,6 @@ def test_intersection_bug(self):
         tm.assert_index_equal(result, b)
 
     def test_month_range_union_tz_pytz(self):
-        tm._skip_if_no_pytz()
         from pytz import timezone
         tz = timezone('US/Eastern')
 
@@ -325,7 +324,7 @@ def test_month_range_union_tz_pytz(self):
 
     def test_month_range_union_tz_dateutil(self):
         tm._skip_if_windows_python_3()
-        tm._skip_if_no_dateutil()
+
         from pandas._libs.tslib import _dateutil_gettz as timezone
         tz = timezone('US/Eastern')
 

pandas/tests/indexes/datetimes/test_tools.py

@@ -1,10 +1,13 @@
 """ test to_datetime """
 
 import sys
+import pytz
 import pytest
 import locale
 import calendar
+import dateutil
 import numpy as np
+from dateutil.parser import parse
 from datetime import datetime, date, time
 from distutils.version import LooseVersion
 
@@ -244,11 +247,7 @@ def test_to_datetime_tz(self):
         pytest.raises(ValueError, lambda: pd.to_datetime(arr))
 
     def test_to_datetime_tz_pytz(self):
-
-        # xref 8260
-        tm._skip_if_no_pytz()
-        import pytz
-
+        # see gh-8260
         us_eastern = pytz.timezone('US/Eastern')
         arr = np.array([us_eastern.localize(datetime(year=2000, month=1, day=1,
                                                      hour=3, minute=0)),
@@ -1124,8 +1123,6 @@ def test_parsers_quarter_invalid(self):
             pytest.raises(ValueError, tools.parse_time_string, case)
 
     def test_parsers_dayfirst_yearfirst(self):
-        tm._skip_if_no_dateutil()
-
         # OK
         # 2.5.1 10-11-12   [dayfirst=0, yearfirst=0] -> 2012-10-11 00:00:00
         # 2.5.2 10-11-12   [dayfirst=0, yearfirst=1] -> 2012-10-11 00:00:00
@@ -1166,7 +1163,6 @@ def test_parsers_dayfirst_yearfirst(self):
         # 2.5.2 20/12/21   [dayfirst=1, yearfirst=0] -> 2021-12-20 00:00:00
         # 2.5.3 20/12/21   [dayfirst=1, yearfirst=0] -> 2021-12-20 00:00:00
 
-        import dateutil
         is_lt_253 = dateutil.__version__ < LooseVersion('2.5.3')
 
         # str : dayfirst, yearfirst, expected
@@ -1187,7 +1183,6 @@ def test_parsers_dayfirst_yearfirst(self):
                               (True, True,
                                datetime(2020, 12, 21))]}
 
-        from dateutil.parser import parse
         for date_str, values in compat.iteritems(cases):
             for dayfirst, yearfirst, expected in values:
 
@@ -1221,9 +1216,6 @@ def test_parsers_dayfirst_yearfirst(self):
                 assert result4 == expected
 
     def test_parsers_timestring(self):
-        tm._skip_if_no_dateutil()
-        from dateutil.parser import parse
-
         # must be the same as dateutil result
         cases = {'10:15': (parse('10:15'), datetime(1, 1, 1, 10, 15)),
                  '9:05': (parse('9:05'), datetime(1, 1, 1, 9, 5))}
@@ -1365,7 +1357,6 @@ def test_parsers_iso8601(self):
 class TestArrayToDatetime(object):
 
     def test_try_parse_dates(self):
-        from dateutil.parser import parse
         arr = np.array(['5/1/2000', '6/1/2000', '7/1/2000'], dtype=object)
 
         result = lib.try_parse_dates(arr, dayfirst=True)

pandas/tests/io/formats/test_format.py

@@ -7,6 +7,8 @@
 from __future__ import print_function
 import re
 
+import pytz
+import dateutil
 import itertools
 from operator import methodcaller
 import os
@@ -1548,17 +1550,15 @@ def get_ipython():
 
     def test_pprint_pathological_object(self):
         """
-        if the test fails, the stack will overflow and nose crash,
-        but it won't hang.
+        If the test fails, it at least won't hang.
         """
 
         class A:
-
             def __getitem__(self, key):
                 return 3  # obviously simplified
 
         df = DataFrame([A()])
-        repr(df)  # just don't dine
+        repr(df)  # just don't die
 
     def test_float_trim_zeros(self):
         vals = [2.08430917305e+10, 3.52205017305e+10, 2.30674817305e+10,
@@ -2508,10 +2508,6 @@ def test_no_tz(self):
         assert str(ts_nanos_micros) == "1970-01-01 00:00:00.000001200"
 
     def test_tz_pytz(self):
-        tm._skip_if_no_pytz()
-
-        import pytz
-
         dt_date = datetime(2013, 1, 2, tzinfo=pytz.utc)
         assert str(dt_date) == str(Timestamp(dt_date))
 
@@ -2522,8 +2518,6 @@ def test_tz_pytz(self):
         assert str(dt_datetime_us) == str(Timestamp(dt_datetime_us))
 
     def test_tz_dateutil(self):
-        tm._skip_if_no_dateutil()
-        import dateutil
         utc = dateutil.tz.tzutc()
 
         dt_date = datetime(2013, 1, 2, tzinfo=utc)