code sample for pandas-dev#47284

Author: simonjayhawkins

bisect/47284.py

@@ -0,0 +1,17 @@
+# REGR: assignment of pd.NA with enlargement gives object dtype with IntegerArray #47284
+
+import pandas as pd
+
+print(pd.__version__)
+
+# gets upcast to object
+df = pd.DataFrame({"a": [1, 2, 3]}, dtype="Int64")
+df.loc[4] = pd.NA
+print(df.dtypes)
+
+expected = pd.DataFrame(
+    {"a": [1, 2, 3, None]},
+    dtype="Int64",
+    index=pd.Int64Index([0, 1, 2, 4], dtype="int64"),
+)
+pd.testing.assert_frame_equal(df, expected)