TST: fixed one tests and added two more for pandas-dev#15686

pandas/tests/indexing/test_iloc.py

@@ -288,15 +288,33 @@ def test_iloc_setitem_dups(self):
         # iloc with a mask aligning from another iloc
         df1 = DataFrame([{'A': None, 'B': 1}, {'A': 2, 'B': 2}])
         df2 = DataFrame([{'A': 3, 'B': 3}, {'A': 4, 'B': 4}])
-        df = concat([df1, df2], axis=1)
+        df_orig = concat([df1, df2], axis=1)
+        df = df_orig.copy()
 
+        # GH 15686
+        # iloc with mask, duplicated index and multiple blocks
         expected = df.fillna(3)
-        expected['A'] = expected['A'].astype('float64')
+        expected.iloc[:, 0] = expected.iloc[:, 0].astype('float64')
         inds = np.isnan(df.iloc[:, 0])
         mask = inds[inds].index
         df.iloc[mask, 0] = df.iloc[mask, 2]
         tm.assert_frame_equal(df, expected)
 
+        # GH 15686
+        # iloc with scalar, duplicated index and multiple blocks
+        df = df_orig.copy()
+        expected = df.fillna(15)
+        df.iloc[0, 0] = 15
+        tm.assert_frame_equal(df, expected)
+
+        # GH 15686
+        # iloc with repeated value, duplicated index and multiple blocks
+        df = df_orig.copy()
+        expected = concat([DataFrame([{'A': 15, 'B': 1}, {'A': 15, 'B': 2}]),
+                          df2], axis=1)
+        df.iloc[:, 0] = 15
+        tm.assert_frame_equal(df, expected)
+
         # del a dup column across blocks
         expected = DataFrame({0: [1, 2], 1: [3, 4]})
         expected.columns = ['B', 'B']