TST: Add period and other dtype related tests

 - [x] tests added / passed   - [x] passes ``git diff upstream/master
| flake8 --diff``    - xref #12549   - added more ``Period`` related
tests in preparation for period dtype.

Author: sinhrks <[email protected]>

Closes #12748 from sinhrks/period_test2 and squashes the following commits:

a9295a6 [sinhrks] TST: Add period and other dtype related tests

Author: sinhrks

pandas/tests/frame/test_constructors.py

@@ -483,6 +483,20 @@ def create_data(constructor):
         assert_frame_equal(result_timedelta, expected)
         assert_frame_equal(result_Timedelta, expected)
 
+    def test_constructor_period(self):
+        # PeriodIndex
+        a = pd.PeriodIndex(['2012-01', 'NaT', '2012-04'], freq='M')
+        b = pd.PeriodIndex(['2012-02-01', '2012-03-01', 'NaT'], freq='D')
+        df = pd.DataFrame({'a': a, 'b': b})
+        self.assertEqual(df['a'].dtype, 'object')
+        self.assertEqual(df['b'].dtype, 'object')
+
+        # list of periods
+        df = pd.DataFrame({'a': a.asobject.tolist(),
+                           'b': b.asobject.tolist()})
+        self.assertEqual(df['a'].dtype, 'object')
+        self.assertEqual(df['b'].dtype, 'object')
+
     def test_nested_dict_frame_constructor(self):
         rng = pd.period_range('1/1/2000', periods=5)
         df = DataFrame(randn(10, 5), columns=rng)

pandas/tests/indexes/test_base.py

@@ -103,6 +103,50 @@ def test_construction_list_mixed_tuples(self):
         self.assertIsInstance(idx2, Index) and self.assertNotInstance(
             idx2, MultiIndex)
 
+    def test_constructor_from_index_datetimetz(self):
+        idx = pd.date_range('2015-01-01 10:00', freq='D', periods=3,
+                            tz='US/Eastern')
+        result = pd.Index(idx)
+        tm.assert_index_equal(result, idx)
+        self.assertEqual(result.tz, idx.tz)
+
+        result = pd.Index(idx.asobject)
+        tm.assert_index_equal(result, idx)
+        self.assertEqual(result.tz, idx.tz)
+
+    def test_constructor_from_index_timedelta(self):
+        idx = pd.timedelta_range('1 days', freq='D', periods=3)
+        result = pd.Index(idx)
+        tm.assert_index_equal(result, idx)
+
+        result = pd.Index(idx.asobject)
+        tm.assert_index_equal(result, idx)
+
+    def test_constructor_from_index_period(self):
+        idx = pd.period_range('2015-01-01', freq='D', periods=3)
+        result = pd.Index(idx)
+        tm.assert_index_equal(result, idx)
+
+        result = pd.Index(idx.asobject)
+        tm.assert_index_equal(result, idx)
+
+    def test_constructor_from_series_datetimetz(self):
+        idx = pd.date_range('2015-01-01 10:00', freq='D', periods=3,
+                            tz='US/Eastern')
+        result = pd.Index(pd.Series(idx))
+        tm.assert_index_equal(result, idx)
+        self.assertEqual(result.tz, idx.tz)
+
+    def test_constructor_from_series_timedelta(self):
+        idx = pd.timedelta_range('1 days', freq='D', periods=3)
+        result = pd.Index(pd.Series(idx))
+        tm.assert_index_equal(result, idx)
+
+    def test_constructor_from_series_period(self):
+        idx = pd.period_range('2015-01-01', freq='D', periods=3)
+        result = pd.Index(pd.Series(idx))
+        tm.assert_index_equal(result, idx)
+
     def test_constructor_from_series(self):
 
         expected = DatetimeIndex([Timestamp('20110101'), Timestamp('20120101'),

pandas/tests/indexes/test_multi.py

@@ -558,6 +558,47 @@ def test_from_arrays(self):
                                                        ])))
         self.assertTrue(result.levels[1].equals(Index(['a', 'b'])))
 
+    def test_from_arrays_index_series_datetimetz(self):
+        idx1 = pd.date_range('2015-01-01 10:00', freq='D', periods=3,
+                             tz='US/Eastern')
+        idx2 = pd.date_range('2015-01-01 10:00', freq='H', periods=3,
+                             tz='Asia/Tokyo')
+        result = pd.MultiIndex.from_arrays([idx1, idx2])
+        tm.assert_index_equal(result.get_level_values(0), idx1)
+        tm.assert_index_equal(result.get_level_values(1), idx2)
+
+        result2 = pd.MultiIndex.from_arrays([pd.Series(idx1), pd.Series(idx2)])
+        tm.assert_index_equal(result2.get_level_values(0), idx1)
+        tm.assert_index_equal(result2.get_level_values(1), idx2)
+
+        tm.assert_index_equal(result, result2)
+
+    def test_from_arrays_index_series_timedelta(self):
+        idx1 = pd.timedelta_range('1 days', freq='D', periods=3)
+        idx2 = pd.timedelta_range('2 hours', freq='H', periods=3)
+        result = pd.MultiIndex.from_arrays([idx1, idx2])
+        tm.assert_index_equal(result.get_level_values(0), idx1)
+        tm.assert_index_equal(result.get_level_values(1), idx2)
+
+        result2 = pd.MultiIndex.from_arrays([pd.Series(idx1), pd.Series(idx2)])
+        tm.assert_index_equal(result2.get_level_values(0), idx1)
+        tm.assert_index_equal(result2.get_level_values(1), idx2)
+
+        tm.assert_index_equal(result, result2)
+
+    def test_from_arrays_index_series_period(self):
+        idx1 = pd.period_range('2011-01-01', freq='D', periods=3)
+        idx2 = pd.period_range('2015-01-01', freq='H', periods=3)
+        result = pd.MultiIndex.from_arrays([idx1, idx2])
+        tm.assert_index_equal(result.get_level_values(0), idx1)
+        tm.assert_index_equal(result.get_level_values(1), idx2)
+
+        result2 = pd.MultiIndex.from_arrays([pd.Series(idx1), pd.Series(idx2)])
+        tm.assert_index_equal(result2.get_level_values(0), idx1)
+        tm.assert_index_equal(result2.get_level_values(1), idx2)
+
+        tm.assert_index_equal(result, result2)
+
     def test_from_product(self):
 
         first = ['foo', 'bar', 'buz']

pandas/tests/series/test_constructors.py

@@ -498,6 +498,8 @@ def test_constructor_periodindex(self):
         expected = Series(pi.asobject)
         assert_series_equal(s, expected)
 
+        self.assertEqual(s.dtype, 'object')
+
     def test_constructor_dict(self):
         d = {'a': 0., 'b': 1., 'c': 2.}
         result = Series(d, index=['b', 'c', 'd', 'a'])

pandas/tests/test_categorical.py

@@ -340,6 +340,31 @@ def test_constructor_with_datetimelike(self):
             result = repr(c)
             self.assertTrue('NaT' in result)
 
+    def test_constructor_from_index_series_datetimetz(self):
+        idx = pd.date_range('2015-01-01 10:00', freq='D', periods=3,
+                            tz='US/Eastern')
+        result = pd.Categorical.from_array(idx)
+        tm.assert_index_equal(result.categories, idx)
+
+        result = pd.Categorical.from_array(pd.Series(idx))
+        tm.assert_index_equal(result.categories, idx)
+
+    def test_constructor_from_index_series_timedelta(self):
+        idx = pd.timedelta_range('1 days', freq='D', periods=3)
+        result = pd.Categorical.from_array(idx)
+        tm.assert_index_equal(result.categories, idx)
+
+        result = pd.Categorical.from_array(pd.Series(idx))
+        tm.assert_index_equal(result.categories, idx)
+
+    def test_constructor_from_index_series_period(self):
+        idx = pd.period_range('2015-01-01', freq='D', periods=3)
+        result = pd.Categorical.from_array(idx)
+        tm.assert_index_equal(result.categories, idx)
+
+        result = pd.Categorical.from_array(pd.Series(idx))
+        tm.assert_index_equal(result.categories, idx)
+
     def test_from_codes(self):
 
         # too few categories

pandas/tests/test_dtypes.py

@@ -4,6 +4,7 @@
 import nose
 import numpy as np
 from pandas import Series, Categorical, date_range
+import pandas.core.common as com
 from pandas.core.common import (CategoricalDtype, is_categorical_dtype,
                                 is_categorical, DatetimeTZDtype,
                                 is_datetime64tz_dtype, is_datetimetz,
@@ -97,6 +98,12 @@ def test_subclass(self):
         self.assertTrue(issubclass(type(a), type(a)))
         self.assertTrue(issubclass(type(a), type(b)))
 
+    def test_coerce_to_dtype(self):
+        self.assertEqual(com._coerce_to_dtype('datetime64[ns, US/Eastern]'),
+                         DatetimeTZDtype('ns', 'US/Eastern'))
+        self.assertEqual(com._coerce_to_dtype('datetime64[ns, Asia/Tokyo]'),
+                         DatetimeTZDtype('ns', 'Asia/Tokyo'))
+
     def test_compat(self):
         self.assertFalse(is_datetime64_ns_dtype(self.dtype))
         self.assertFalse(is_datetime64_ns_dtype('datetime64[ns, US/Eastern]'))

pandas/tools/tests/test_merge.py

@@ -1065,6 +1065,8 @@ def test_merge_on_datetime64tz(self):
             'key': [1., 2, 3]})
         result = pd.merge(left, right, on='key', how='outer')
         assert_frame_equal(result, expected)
+        self.assertEqual(result['value_x'].dtype, 'datetime64[ns, US/Eastern]')
+        self.assertEqual(result['value_y'].dtype, 'datetime64[ns, US/Eastern]')
 
     def test_merge_on_periods(self):
         left = pd.DataFrame({'key': pd.period_range('20151010', periods=2,
@@ -1095,6 +1097,8 @@ def test_merge_on_periods(self):
                               'key': [1., 2, 3]})
         result = pd.merge(left, right, on='key', how='outer')
         assert_frame_equal(result, expected)
+        self.assertEqual(result['value_x'].dtype, 'object')
+        self.assertEqual(result['value_y'].dtype, 'object')
 
     def test_concat_NaT_series(self):
         # GH 11693
@@ -1216,32 +1220,37 @@ def test_concat_period_series(self):
         expected = Series([x[0], x[1], y[0], y[1]], dtype='object')
         result = concat([x, y], ignore_index=True)
         tm.assert_series_equal(result, expected)
+        self.assertEqual(result.dtype, 'object')
 
         # different freq
         x = Series(pd.PeriodIndex(['2015-11-01', '2015-12-01'], freq='D'))
         y = Series(pd.PeriodIndex(['2015-10-01', '2016-01-01'], freq='M'))
         expected = Series([x[0], x[1], y[0], y[1]], dtype='object')
         result = concat([x, y], ignore_index=True)
         tm.assert_series_equal(result, expected)
+        self.assertEqual(result.dtype, 'object')
 
         x = Series(pd.PeriodIndex(['2015-11-01', '2015-12-01'], freq='D'))
         y = Series(pd.PeriodIndex(['2015-11-01', '2015-12-01'], freq='M'))
         expected = Series([x[0], x[1], y[0], y[1]], dtype='object')
         result = concat([x, y], ignore_index=True)
         tm.assert_series_equal(result, expected)
+        self.assertEqual(result.dtype, 'object')
 
         # non-period
         x = Series(pd.PeriodIndex(['2015-11-01', '2015-12-01'], freq='D'))
         y = Series(pd.DatetimeIndex(['2015-11-01', '2015-12-01']))
         expected = Series([x[0], x[1], y[0], y[1]], dtype='object')
         result = concat([x, y], ignore_index=True)
         tm.assert_series_equal(result, expected)
+        self.assertEqual(result.dtype, 'object')
 
         x = Series(pd.PeriodIndex(['2015-11-01', '2015-12-01'], freq='D'))
         y = Series(['A', 'B'])
         expected = Series([x[0], x[1], y[0], y[1]], dtype='object')
         result = concat([x, y], ignore_index=True)
         tm.assert_series_equal(result, expected)
+        self.assertEqual(result.dtype, 'object')
 
     def test_indicator(self):
         # PR #10054. xref #7412 and closes #8790.

pandas/tseries/tests/test_period.py

@@ -3865,11 +3865,30 @@ def test_auto_conversion(self):
         series = Series(list(period_range('2000-01-01', periods=10, freq='D')))
         self.assertEqual(series.dtype, 'object')
 
+        series = pd.Series([pd.Period('2011-01-01', freq='D'),
+                            pd.Period('2011-02-01', freq='D')])
+        self.assertEqual(series.dtype, 'object')
+
+    def test_getitem(self):
+        self.assertEqual(self.series[1], pd.Period('2000-01-02', freq='D'))
+
+        result = self.series[[2, 4]]
+        exp = pd.Series([pd.Period('2000-01-03', freq='D'),
+                         pd.Period('2000-01-05', freq='D')],
+                        index=[2, 4])
+        self.assert_series_equal(result, exp)
+        self.assertEqual(result.dtype, 'object')
+
     def test_constructor_cant_cast_period(self):
         with tm.assertRaises(TypeError):
             Series(period_range('2000-01-01', periods=10, freq='D'),
                    dtype=float)
 
+    def test_constructor_cast_object(self):
+        s = Series(period_range('1/1/2000', periods=10), dtype=object)
+        exp = Series(period_range('1/1/2000', periods=10))
+        tm.assert_series_equal(s, exp)
+
     def test_series_comparison_scalars(self):
         val = pd.Period('2000-01-04', freq='D')
         result = self.series > val

pandas/tseries/tests/test_timeseries.py

@@ -3944,8 +3944,17 @@ def test_auto_conversion(self):
         self.assertEqual(series.dtype, 'M8[ns]')
 
     def test_constructor_cant_cast_datetime64(self):
-        self.assertRaises(TypeError, Series,
-                          date_range('1/1/2000', periods=10), dtype=float)
+        msg = "Cannot cast datetime64 to "
+        with tm.assertRaisesRegexp(TypeError, msg):
+            Series(date_range('1/1/2000', periods=10), dtype=float)
+
+        with tm.assertRaisesRegexp(TypeError, msg):
+            Series(date_range('1/1/2000', periods=10), dtype=int)
+
+    def test_constructor_cast_object(self):
+        s = Series(date_range('1/1/2000', periods=10), dtype=object)
+        exp = Series(date_range('1/1/2000', periods=10))
+        tm.assert_series_equal(s, exp)
 
     def test_series_comparison_scalars(self):
         val = datetime(2000, 1, 4)
@@ -4004,6 +4013,9 @@ def test_intercept_astype_object(self):
 
         df = DataFrame({'a': self.series,
                         'b': np.random.randn(len(self.series))})
+        exp_dtypes = pd.Series([np.dtype('datetime64[ns]'),
+                                np.dtype('float64')], index=['a', 'b'])
+        tm.assert_series_equal(df.dtypes, exp_dtypes)
 
         result = df.values.squeeze()
         self.assertTrue((result[:, 0] == expected.values).all())