test(cudf): move infer_format regression tests to test_to_datetime.py

Address review feedback: relocate the parametrized infer_format unit test
and the to_datetime integration regression test from test_astype.py to
test_to_datetime.py, where datetime-related tests belong. No behavior
change; the module-level infer_format import moves with them.

Author: vyasr

python/cudf/cudf/tests/general_functions/test_to_datetime.py

@@ -12,6 +12,7 @@
 from cudf.testing._utils import (
     assert_exceptions_equal,
 )
+from cudf.utils.temporal import infer_format
 
 
 @pytest.mark.parametrize(
@@ -434,3 +435,21 @@ def test_datetime_index_tz_dtype_wall_time(data):
     )
     expected = pd.DatetimeIndex(data, dtype="datetime64[s, US/Eastern]")
     assert_eq(result, expected)
+
+
+@pytest.mark.parametrize(
+    "bad_input",
+    ["1.2", "9.9", "2078~1.15"],
+)
+def test_infer_format_rejects_non_datetime_dotted_strings(bad_input):
+    with pytest.raises(
+        ValueError, match="Unable to infer the timestamp format"
+    ):
+        infer_format(bad_input)
+
+
+def test_to_datetime_rejects_non_datetime_dotted_string():
+    with pytest.raises(
+        ValueError, match="Unable to infer the timestamp format"
+    ):
+        cudf.to_datetime(cudf.Series(["1.2"]))

python/cudf/cudf/tests/series/methods/test_astype.py

@@ -15,7 +15,6 @@
 from cudf.core.column.numerical import NumericalColumn
 from cudf.testing import assert_eq
 from cudf.testing._utils import assert_exceptions_equal, expect_warning_if
-from cudf.utils.temporal import infer_format
 
 
 @pytest.mark.parametrize(
@@ -596,24 +595,6 @@ def test_str_to_datetime_error():
     )
 
 
-@pytest.mark.parametrize(
-    "bad_input",
-    ["1.2", "9.9", "2078~1.15"],
-)
-def test_infer_format_rejects_non_datetime_dotted_strings(bad_input):
-    with pytest.raises(
-        ValueError, match="Unable to infer the timestamp format"
-    ):
-        infer_format(bad_input)
-
-
-def test_to_datetime_rejects_non_datetime_dotted_string():
-    with pytest.raises(
-        ValueError, match="Unable to infer the timestamp format"
-    ):
-        cudf.to_datetime(cudf.Series(["1.2"]))
-
-
 @pytest.mark.parametrize("timezone", ["", "Z"])
 @pytest.mark.parametrize(
     "data",