TST: Add regression tests for GH#63388 (PeriodIndex copy behavior)

Author: zacharym-collins

pandas/tests/copy_view/index/test_periodindex.py

@@ -1,12 +1,15 @@
+import numpy as np
 import pytest
 
 from pandas import (
     Period,
     PeriodIndex,
     Series,
     period_range,
+    array
 )
 import pandas._testing as tm
+from pandas.tests.copy_view.util import get_array
 
 pytestmark = pytest.mark.filterwarnings(
     "ignore:Setting a value on a view:FutureWarning"
@@ -21,3 +24,24 @@ def test_periodindex(box):
     expected = idx.copy(deep=True)
     ser.iloc[0] = Period("2020-12-31")
     tm.assert_index_equal(idx, expected)
+
+
+def test_constructor_copy_input_period_ea_default():
+    # GH 63388
+    arr = array(['2020-01-01', '2020-01-02'], dtype='period[D]')
+    idx = PeriodIndex(arr)
+    assert not tm.shares_memory(arr, idx.array)
+
+
+def test_series_from_temporary_periodindex_readonly_data():
+    # GH 63388
+    arr = array(['2020-01-01', '2020-01-02'], dtype='period[D]')
+    arr._ndarray.flags.writeable = False
+    ser = Series(PeriodIndex(arr))
+    assert not np.shares_memory(arr._ndarray, get_array(ser))
+    ser.iloc[0] = Period('2022-01-01', freq='D')
+    expected = Series(
+        [Period('2022-01-01', freq='D'), Period('2020-01-02', freq='D')], 
+        dtype='period[D]'
+    )
+    tm.assert_series_equal(ser, expected)