TST: added test for ea dtypes conversion to datetimetzdtype (GH37553) (#43270)

Author: lorenzophys

pandas/tests/series/methods/test_astype.py

@@ -16,6 +16,7 @@
     NA,
     Categorical,
     CategoricalDtype,
+    DatetimeTZDtype,
     Index,
     Interval,
     NaT,
@@ -363,6 +364,38 @@ def test_astype_nan_to_bool(self):
         expected = Series(True, dtype="bool")
         tm.assert_series_equal(result, expected)
 
+    @pytest.mark.parametrize(
+        "dtype",
+        tm.ALL_INT_EA_DTYPES + tm.FLOAT_EA_DTYPES,
+    )
+    def test_astype_ea_to_datetimetzdtype(self, dtype):
+        # GH37553
+        result = Series([4, 0, 9], dtype=dtype).astype(DatetimeTZDtype(tz="US/Pacific"))
+        expected = Series(
+            {
+                0: Timestamp("1969-12-31 16:00:00.000000004-08:00", tz="US/Pacific"),
+                1: Timestamp("1969-12-31 16:00:00.000000000-08:00", tz="US/Pacific"),
+                2: Timestamp("1969-12-31 16:00:00.000000009-08:00", tz="US/Pacific"),
+            }
+        )
+
+        if dtype in tm.FLOAT_EA_DTYPES:
+            expected = Series(
+                {
+                    0: Timestamp(
+                        "1970-01-01 00:00:00.000000004-08:00", tz="US/Pacific"
+                    ),
+                    1: Timestamp(
+                        "1970-01-01 00:00:00.000000000-08:00", tz="US/Pacific"
+                    ),
+                    2: Timestamp(
+                        "1970-01-01 00:00:00.000000009-08:00", tz="US/Pacific"
+                    ),
+                }
+            )
+
+        tm.assert_series_equal(result, expected)
+
 
 class TestAstypeString:
     @pytest.mark.parametrize(