Increase test coverage

singer_sdk/_singerlib/utils.py

@@ -7,6 +7,14 @@
 DATETIME_FMT_SAFE = "%Y-%m-%dT%H:%M:%S.%fZ"
 
 
+class NonUTCDatetimeError(Exception):
+    """Raised when a non-UTC datetime is passed to a function expecting UTC."""
+
+    def __init__(self) -> None:
+        """Initialize the exception."""
+        super().__init__("datetime must be pegged at UTC tzoneinfo")
+
+
 def strptime_to_utc(dtimestr: str) -> datetime:
     """Parses a provide datetime string into a UTC datetime object.
 
@@ -34,10 +42,11 @@ def strftime(dtime: datetime, format_str: str = DATETIME_FMT) -> str:
         A string in the specified format
 
     Raises:
-        Exception: if the datetime is not UTC (if it has a nonzero time zone offset)
+        NonUTCDatetimeError: if the datetime is not UTC (if it has a nonzero time zone
+            offset)
     """
     if dtime.utcoffset() != timedelta(0):
-        raise Exception("datetime must be pegged at UTC tzoneinfo")
+        raise NonUTCDatetimeError()
 
     dt_str = None
     try:

tests/_singerlib/test_utils.py

@@ -4,6 +4,7 @@
 import pytz
 
 from singer_sdk._singerlib import strftime, strptime_to_utc
+from singer_sdk._singerlib.utils import NonUTCDatetimeError
 
 
 def test_small_years():
@@ -18,3 +19,23 @@ def test_round_trip():
     parsed_datetime = strptime_to_utc(dtime)
     formatted_datetime = strftime(parsed_datetime)
     assert dtime == formatted_datetime
+
+
+@pytest.mark.parametrize(
+    "dtimestr",
+    [
+        "2021-01-01T00:00:00.000000Z",
+        "2021-01-01T00:00:00.000000+00:00",
+        "2021-01-01T00:00:00.000000+06:00",
+        "2021-01-01T00:00:00.000000-04:00",
+    ],
+    ids=["Z", "offset+0", "offset+6", "offset-4"],
+)
+def test_strptime_to_utc(dtimestr):
+    assert strptime_to_utc(dtimestr).tzinfo == pytz.UTC
+
+
+def test_stftime_non_utc():
+    now = datetime.utcnow().replace(tzinfo=pytz.timezone("America/New_York"))
+    with pytest.raises(NonUTCDatetimeError):
+        strftime(now)