REF/TST: collect reindex tests

Author: jbrockmendel

pandas/tests/frame/methods/test_align.py

@@ -1,12 +1,39 @@
 import numpy as np
 import pytest
+import pytz
 
 import pandas as pd
-from pandas import DataFrame, Index, Series
+from pandas import DataFrame, Index, Series, date_range
 import pandas._testing as tm
 
 
 class TestDataFrameAlign:
+    def test_frame_align_aware(self):
+        idx1 = date_range("2001", periods=5, freq="H", tz="US/Eastern")
+        idx2 = date_range("2001", periods=5, freq="2H", tz="US/Eastern")
+        df1 = DataFrame(np.random.randn(len(idx1), 3), idx1)
+        df2 = DataFrame(np.random.randn(len(idx2), 3), idx2)
+        new1, new2 = df1.align(df2)
+        assert df1.index.tz == new1.index.tz
+        assert df2.index.tz == new2.index.tz
+
+        # different timezones convert to UTC
+
+        # frame with frame
+        df1_central = df1.tz_convert("US/Central")
+        new1, new2 = df1.align(df1_central)
+        assert new1.index.tz == pytz.UTC
+        assert new2.index.tz == pytz.UTC
+
+        # frame with Series
+        new1, new2 = df1.align(df1_central[0], axis=0)
+        assert new1.index.tz == pytz.UTC
+        assert new2.index.tz == pytz.UTC
+
+        df1[0].align(df1_central, axis=0)
+        assert new1.index.tz == pytz.UTC
+        assert new2.index.tz == pytz.UTC
+
     def test_align_float(self, float_frame):
         af, bf = float_frame.align(float_frame)
         assert af._mgr is not float_frame._mgr