Tests for Period immutability

Author: jbrockmendel

pandas/tests/test_lib.py

@@ -248,3 +248,14 @@ def test_empty_like(self):
         expected = np.array([True])
 
         self._check_behavior(arr, expected)
+
+
+
+def test_period_immutable():
+    per = pd.Period('2014Q1')
+    with pytest.raises(AttributeError, message="is not writable"):
+        per.ordinal = 14
+
+    freq = per.freq
+    with pytest.raises(AttributeError, message="is not writable"):
+        per.freq = 2*freq