TST: Add test cases for GH6173, appending to empty df

pandas/tests/indexing/test_loc.py

@@ -804,3 +804,35 @@ def test_loc_uint64(self):
         result = s.loc[[np.iinfo('uint64').max - 1,
                        np.iinfo('uint64').max]]
         tm.assert_series_equal(result, s)
+
+    def test_loc_setitem_empty_append(self):
+        # GH6173, various appends to an empty dataframe
+
+        data = [1, 2, 3]
+        expected = DataFrame({'x': data, 'y': [None] * len(data)})
+
+        # appends to fit length of data
+        df = DataFrame(columns=['x', 'y'])
+        df.loc[:, 'x'] = data
+        tm.assert_frame_equal(df, expected)
+
+        # only appends one value
+        expected = DataFrame({'x': [1.0], 'y': [np.nan]})
+        df = DataFrame(columns=['x', 'y'],
+                       dtype=np.float)
+        df.loc[0, 'x'] = expected.loc[0, 'x']
+        tm.assert_frame_equal(df, expected)
+
+    def test_loc_setitem_empty_append_raises(self):
+        # GH6173, various appends to an empty dataframe
+
+        data = [1, 2]
+        df = DataFrame(columns=['x', 'y'])
+        msg = (r"None of \[Int64Index\(\[0, 1\], dtype='int64'\)\] "
+               r"are in the \[index\]")
+        with pytest.raises(KeyError, match=msg):
+            df.loc[[0, 1], 'x'] = data
+
+        msg = "cannot copy sequence with size 2 to array axis with dimension 0"
+        with pytest.raises(ValueError, match=msg):
+            df.loc[0:2, 'x'] = data

pandas/tests/indexing/test_multiindex.py

@@ -1,3 +1,4 @@
+from datetime import datetime
 from warnings import catch_warnings
 
 import numpy as np
@@ -7,7 +8,8 @@
 
 import pandas as pd
 from pandas import (
-    DataFrame, Index, MultiIndex, Panel, Series, Timestamp, date_range)
+    DataFrame, Index, MultiIndex, Panel, Period, Series, Timestamp, date_range,
+    period_range)
 from pandas.tests.indexing.common import _mklbl
 from pandas.util import testing as tm
 
@@ -1340,3 +1342,20 @@ def test_panel_setitem_with_multiindex(self):
         p5.iloc[0, :, 0] = [1, 2]
         expected = Panel(arr, **axes)
         tm.assert_panel_equal(p5, expected)
+
+
+def test_multiindex_period_datetime():
+    # GH4861, using datetime in period of multiindex raises exception
+
+    idx1 = Index(['a', 'a', 'a', 'b', 'b'])
+    idx2 = period_range('2012-01', periods=len(idx1), freq='M')
+    s = Series(np.random.randn(len(idx1)), [idx1, idx2])
+
+    # try Period as index
+    expected = s.iloc[0]
+    result = s.loc['a', Period('2012-01')]
+    assert result == expected
+
+    # try datetime as index
+    result = s.loc['a', datetime(2012, 1, 1)]
+    assert result == expected