TST: Add PeriodIndex Series truncate test

Author: Licht-T

pandas/tests/indexes/period/test_indexing.py

@@ -310,3 +310,33 @@ def test_take_fill_value(self):
 
         with pytest.raises(IndexError):
             idx.take(np.array([1, -5]))
+
+    def test_truncate(self):
+        # GH 17717
+        idx1 = pd.PeriodIndex([
+            pd.Period('2017-09-02'),
+            pd.Period('2017-09-02'),
+            pd.Period('2017-09-03')
+        ])
+        series1 = pd.Series([1, 2, 3], index=idx1)
+        result1 = series1.truncate(after='2017-09-02')
+
+        expected_idx1 = pd.PeriodIndex([
+            pd.Period('2017-09-02'),
+            pd.Period('2017-09-02')
+        ])
+        tm.assert_series_equal(result1, pd.Series([1, 2], index=expected_idx1))
+
+        idx2 = pd.PeriodIndex([
+            pd.Period('2017-09-03'),
+            pd.Period('2017-09-02'),
+            pd.Period('2017-09-03')
+        ])
+        series2 = pd.Series([1, 2, 3], index=idx2)
+        result2 = series2.truncate(after='2017-09-02')
+
+        expected_idx2 = pd.PeriodIndex([
+            pd.Period('2017-09-03'),
+            pd.Period('2017-09-02')
+        ])
+        tm.assert_series_equal(result2, pd.Series([1, 2], index=expected_idx2))