TST: add tests for keeping dtype in Series.update

pandas/tests/series/test_combine_concat.py

@@ -10,7 +10,7 @@
 import pandas as pd
 from pandas import DataFrame, DatetimeIndex, Series, compat, date_range
 import pandas.util.testing as tm
-from pandas.util.testing import assert_series_equal
+from pandas.util.testing import assert_series_equal, assert_frame_equal
 
 
 class TestSeriesCombine():
@@ -116,8 +116,35 @@ def test_update(self):
  df = DataFrame([{"a": 1}, {"a": 3, "b": 2}])
  df['c'] = np.nan
 
- # this will fail as long as series is a sub-class of ndarray
- # df['c'].update(Series(['foo'],index=[0])) #####
+ df['c'].update(Series(['foo'], index=[0]))
+ expected = DataFrame([[1, np.nan, 'foo'], [3, 2., np.nan]],
+ columns=['a', 'b', 'c'])
+ assert_frame_equal(df, expected)
+
+ def test_update_dtypes(self):
+ s = Series([1., 2., False, True])
+
+ other = Series([45], index=[0])
+ s.update(other)
+
+ expected = Series([45., 2., False, True])
+ assert_series_equal(s, expected)
+
+ s = Series([10, 11, 12])
+ other = Series([61, 63], index=[1, 3])
+ s.update(other)
+
+ expected = Series([10, 61, 12])
+ assert_series_equal(s, expected)
+
+ # we always try to keep original dtype, even if other has different one
+ s.update(other.astype(float))
+ assert_series_equal(s, expected)
+
+ # if keeping the dtype is not possible, we allow upcasting
+ s.update(other + 0.1)
+ expected = Series([10., 61.1, 12.])
+ assert_series_equal(s, expected)
 
  def test_concat_empty_series_dtypes_roundtrips(self):