Adjust test in tools for new string option (#56178)

Author: phofl

pandas/tests/tools/test_to_datetime.py

@@ -183,7 +183,7 @@ def test_to_datetime_format_YYYYMMDD_ignore_with_outofbounds(self, cache):
             errors="ignore",
             cache=cache,
         )
-        expected = Index(["15010101", "20150101", np.nan])
+        expected = Index(["15010101", "20150101", np.nan], dtype=object)
         tm.assert_index_equal(result, expected)
 
     def test_to_datetime_format_YYYYMMDD_coercion(self, cache):
@@ -1206,7 +1206,9 @@ def test_out_of_bounds_errors_ignore2(self):
         # GH#12424
         msg = "errors='ignore' is deprecated"
         with tm.assert_produces_warning(FutureWarning, match=msg):
-            res = to_datetime(Series(["2362-01-01", np.nan]), errors="ignore")
+            res = to_datetime(
+                Series(["2362-01-01", np.nan], dtype=object), errors="ignore"
+            )
         exp = Series(["2362-01-01", np.nan], dtype=object)
         tm.assert_series_equal(res, exp)
 
@@ -1489,7 +1491,7 @@ def test_datetime_invalid_index(self, values, format):
             warn, match="Could not infer format", raise_on_extra_warnings=False
         ):
             res = to_datetime(values, errors="ignore", format=format)
-        tm.assert_index_equal(res, Index(values))
+        tm.assert_index_equal(res, Index(values, dtype=object))
 
         with tm.assert_produces_warning(
             warn, match="Could not infer format", raise_on_extra_warnings=False
@@ -1667,7 +1669,7 @@ def test_to_datetime_coerce_oob(self, string_arg, format, outofbounds):
         "errors, expected",
         [
             ("coerce", Index([NaT, NaT])),
-            ("ignore", Index(["200622-12-31", "111111-24-11"])),
+            ("ignore", Index(["200622-12-31", "111111-24-11"], dtype=object)),
         ],
     )
     def test_to_datetime_malformed_no_raise(self, errors, expected):
@@ -2681,7 +2683,7 @@ def test_string_na_nat_conversion_malformed(self, cache):
 
         result = to_datetime(malformed, errors="ignore", cache=cache)
         # GH 21864
-        expected = Index(malformed)
+        expected = Index(malformed, dtype=object)
         tm.assert_index_equal(result, expected)
 
         with pytest.raises(ValueError, match=msg):
@@ -3670,7 +3672,7 @@ def test_to_datetime_mixed_not_necessarily_iso8601_raise():
     ("errors", "expected"),
     [
         ("coerce", DatetimeIndex(["2020-01-01 00:00:00", NaT])),
-        ("ignore", Index(["2020-01-01", "01-01-2000"])),
+        ("ignore", Index(["2020-01-01", "01-01-2000"], dtype=object)),
     ],
 )
 def test_to_datetime_mixed_not_necessarily_iso8601_coerce(errors, expected):