Add tests for TypeError when index isn't a DatetimeIndex

Author: tp

doc/source/whatsnew/v0.23.0.txt

@@ -916,10 +916,10 @@ Datetimelike API Changes
 - :class:`CacheableOffset` and :class:`WeekDay` are no longer available in the ``pandas.tseries.offsets`` module (:issue:`17830`)
 - ``pandas.tseries.frequencies.get_freq_group()`` and ``pandas.tseries.frequencies.DAYS`` are removed from the public API (:issue:`18034`)
 - :func:`Series.truncate` and :func:`DataFrame.truncate` will raise a ``ValueError`` if the index is not sorted instead of an unhelpful ``KeyError`` (:issue:`17935`)
-- :attr:`Series.at_time` and :attr:`DataFrame.at_time` will now raise a ``TypeError``
+- :attr:`Series.first` and :attr:`DataFrame.first` will now raise a ``TypeError``
+  rather than ``NotImplementedError`` when index is not a :class:`DatetimeIndex`` (:issue:`20725`).
+- :attr:`Series.last` and :attr:`DateFrame.last` will now raise a ``TypeError``
   rather than ``NotImplementedError`` when index is not a :class:`DatetimeIndex`` (:issue:`20725`).
-- :attr:`Series.between_time` and :attr:`DateFrame.between_time` will now raise
-  a ``TypeError`` rather than ``NotImplementedError`` when index is not a :class:`DatetimeIndex`` (:issue:`20725`).
 - Restricted ``DateOffset`` keyword arguments. Previously, ``DateOffset`` subclasses allowed arbitrary keyword arguments which could lead to unexpected behavior. Now, only valid arguments will be accepted. (:issue:`17176`, :issue:`18226`).
 - :func:`pandas.merge` provides a more informative error message when trying to merge on timezone-aware and timezone-naive columns (:issue:`15800`)
 - For :class:`DatetimeIndex` and :class:`TimedeltaIndex` with ``freq=None``, addition or subtraction of integer-dtyped array or ``Index`` will raise ``NullFrequencyError`` instead of ``TypeError`` (:issue:`19895`)

pandas/tests/frame/test_timeseries.py

@@ -539,7 +539,59 @@ def test_first_last_valid(self):
         assert frame.first_valid_index().freq == frame.index.freq
         assert frame.last_valid_index().freq == frame.index.freq
 
-    def test_at_time_frame(self):
+    def test_first_subset(self):
+        ts = tm.makeTimeDataFrame(freq='12h')
+        result = ts.first('10d')
+        assert len(result) == 20
+
+        ts = tm.makeTimeDataFrame(freq='D')
+        result = ts.first('10d')
+        assert len(result) == 10
+
+        result = ts.first('3M')
+        expected = ts[:'3/31/2000']
+        assert_frame_equal(result, expected)
+
+        result = ts.first('21D')
+        expected = ts[:21]
+        assert_frame_equal(result, expected)
+
+        result = ts[:0].first('3M')
+        assert_frame_equal(result, ts[:0])
+
+    def test_first_raises(self):
+        # GH20725
+        df = pd.DataFrame([[1, 2, 3], [4, 5, 6]])
+        with pytest.raises(TypeError):  # index is not a DatetimeIndex
+            df.first('1D')
+
+    def test_last_subset(self):
+        ts = tm.makeTimeDataFrame(freq='12h')
+        result = ts.last('10d')
+        assert len(result) == 20
+
+        ts = tm.makeTimeDataFrame(nper=30, freq='D')
+        result = ts.last('10d')
+        assert len(result) == 10
+
+        result = ts.last('21D')
+        expected = ts['2000-01-10':]
+        assert_frame_equal(result, expected)
+
+        result = ts.last('21D')
+        expected = ts[-21:]
+        assert_frame_equal(result, expected)
+
+        result = ts[:0].last('3M')
+        assert_frame_equal(result, ts[:0])
+
+    def test_last_raises(self):
+        # GH20725
+        df = pd.DataFrame([[1, 2, 3], [4, 5, 6]])
+        with pytest.raises(TypeError):  # index is not a DatetimeIndex
+            df.last('1D')
+
+    def test_at_time(self):
         rng = date_range('1/1/2000', '1/5/2000', freq='5min')
         ts = DataFrame(np.random.randn(len(rng), 2), index=rng)
         rs = ts.at_time(rng[1])
@@ -569,7 +621,13 @@ def test_at_time_frame(self):
         rs = ts.at_time('16:00')
         assert len(rs) == 0
 
-    def test_between_time_frame(self):
+    def test_at_time_raises(self):
+        # GH20725
+        df = pd.DataFrame([[1, 2, 3], [4, 5, 6]])
+        with pytest.raises(TypeError):  # index is not a DatetimeIndex
+            df.at_time('00:00')
+
+    def test_between_time(self):
         rng = date_range('1/1/2000', '1/5/2000', freq='5min')
         ts = DataFrame(np.random.randn(len(rng), 2), index=rng)
         stime = time(0, 0)
@@ -629,6 +687,12 @@ def test_between_time_frame(self):
                 else:
                     assert (t < etime) or (t >= stime)
 
+    def test_between_time_raises(self):
+        # GH20725
+        df = pd.DataFrame([[1, 2, 3], [4, 5, 6]])
+        with pytest.raises(TypeError):  # index is not a DatetimeIndex
+            df.between_time(start_time='00:00', end_time='12:00')
+
     def test_operation_on_NaT(self):
         # Both NaT and Timestamp are in DataFrame.
         df = pd.DataFrame({'foo': [pd.NaT, pd.NaT,

pandas/tests/series/test_timeseries.py

@@ -628,6 +628,12 @@ def test_first_subset(self):
         result = ts[:0].first('3M')
         assert_series_equal(result, ts[:0])
 
+    def test_first_raises(self):
+        # GH20725
+        ser = pd.Series('a b c'.split())
+        with pytest.raises(TypeError):  # index is not a DatetimeIndex
+            ser.first('1D')
+
     def test_last_subset(self):
         ts = _simple_ts('1/1/2000', '1/1/2010', freq='12h')
         result = ts.last('10d')
@@ -648,6 +654,12 @@ def test_last_subset(self):
         result = ts[:0].last('3M')
         assert_series_equal(result, ts[:0])
 
+    def test_last_raises(self):
+        # GH20725
+        ser = pd.Series('a b c'.split())
+        with pytest.raises(TypeError):  # index is not a DatetimeIndex
+            ser.last('1D')
+
     def test_format_pre_1900_dates(self):
         rng = date_range('1/1/1850', '1/1/1950', freq='A-DEC')
         rng.format()
@@ -696,6 +708,12 @@ def test_at_time(self):
         rs = ts.at_time('16:00')
         assert len(rs) == 0
 
+    def test_at_time_raises(self):
+        # GH20725
+        ser = pd.Series('a b c'.split())
+        with pytest.raises(TypeError):  # index is not a DatetimeIndex
+            ser.at_time('00:00')
+
     def test_between(self):
         series = Series(date_range('1/1/2000', periods=10))
         left, right = series[[2, 7]]
@@ -764,6 +782,12 @@ def test_between_time(self):
                 else:
                     assert (t < etime) or (t >= stime)
 
+    def test_between_time_raises(self):
+        # GH20725
+        ser = pd.Series('a b c'.split())
+        with pytest.raises(TypeError):  # index is not a DatetimeIndex
+            ser.between_time(start_time='00:00', end_time='12:00')
+
     def test_between_time_types(self):
         # GH11818
         rng = date_range('1/1/2000', '1/5/2000', freq='5min')