fixup tests

Author: MarcoGorelli

pandas/tests/tools/test_to_datetime.py

@@ -341,20 +341,19 @@ def test_to_datetime_with_non_exact(self, cache):
         tm.assert_series_equal(result, expected)
 
     @pytest.mark.parametrize(
-        "arg, warning",
+        "arg",
         [
-            ("2012-01-01 09:00:00.000000001", UserWarning),
-            ("2012-01-01 09:00:00.000001", None),
-            ("2012-01-01 09:00:00.001", UserWarning),
-            ("2012-01-01 09:00:00.001000", None),
-            ("2012-01-01 09:00:00.001000000", UserWarning),
+            "2012-01-01 09:00:00.000000001",
+            "2012-01-01 09:00:00.000001",
+            "2012-01-01 09:00:00.001",
+            "2012-01-01 09:00:00.001000",
+            "2012-01-01 09:00:00.001000000",
         ],
     )
-    def test_parse_nanoseconds_with_formula(self, cache, arg, warning):
+    def test_parse_nanoseconds_with_formula(self, cache, arg):
         # GH8989
         # truncating the nanoseconds when a format was provided
-        with tm.assert_produces_warning(warning, match="Could not infer format"):
-            expected = to_datetime(arg, cache=cache)
+        expected = to_datetime(arg, cache=cache)
         result = to_datetime(arg, format="%Y-%m-%d %H:%M:%S.%f", cache=cache)
         assert result == expected
 
@@ -2649,8 +2648,7 @@ def test_arg_tz_ns_unit(self, offset, utc, exp):
         # GH 25546
         arg = "2019-01-01T00:00:00.000" + offset
         result = to_datetime([arg], unit="ns", utc=utc)
-        with tm.assert_produces_warning(UserWarning, match="Could not infer format"):
-            expected = to_datetime([exp])
+        expected = to_datetime([exp])
         tm.assert_index_equal(result, expected)