I am done

rl/Lib/site-packages/pandas/tests/tslibs/test_tzconversion.py

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+import numpy as np
+import pytest
+import pytz
+
+from pandas._libs.tslibs.tzconversion import tz_localize_to_utc
+
+
+class TestTZLocalizeToUTC:
+    def test_tz_localize_to_utc_ambiguous_infer(self):
+        # val is a timestamp that is ambiguous when localized to US/Eastern
+        val = 1_320_541_200_000_000_000
+        vals = np.array([val, val - 1, val], dtype=np.int64)
+
+        with pytest.raises(pytz.AmbiguousTimeError, match="2011-11-06 01:00:00"):
+            tz_localize_to_utc(vals, pytz.timezone("US/Eastern"), ambiguous="infer")
+
+        with pytest.raises(pytz.AmbiguousTimeError, match="are no repeated times"):
+            tz_localize_to_utc(vals[:1], pytz.timezone("US/Eastern"), ambiguous="infer")
+
+        vals[1] += 1
+        msg = "There are 2 dst switches when there should only be 1"
+        with pytest.raises(pytz.AmbiguousTimeError, match=msg):
+            tz_localize_to_utc(vals, pytz.timezone("US/Eastern"), ambiguous="infer")