diff --git a/ingestor/chalicelib/tests/__init__.py b/ingestor/chalicelib/tests/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/ingestor/chalicelib/tests/test_util.py b/ingestor/chalicelib/tests/test_util.py
new file mode 100644
index 0000000..b015a24
--- /dev/null
+++ b/ingestor/chalicelib/tests/test_util.py
@@ -0,0 +1,29 @@
+from datetime import date, datetime
+from ..date_utils import EASTERN_TIME, service_date
+
+
+def test_service_date():
+    assert service_date(datetime(2023, 12, 15, 3, 0, 0)) == date(2023, 12, 15)
+    assert service_date(datetime(2023, 12, 15, 5, 45, 0)) == date(2023, 12, 15)
+    assert service_date(datetime(2023, 12, 15, 7, 15, 0)) == date(2023, 12, 15)
+    assert service_date(datetime(2023, 12, 15, 23, 59, 59)) == date(2023, 12, 15)
+    assert service_date(datetime(2023, 12, 16, 0, 0, 0)) == date(2023, 12, 15)
+    assert service_date(datetime(2023, 12, 16, 2, 59, 59)) == date(2023, 12, 15)
+
+
+def test_localized_datetime():
+    assert service_date(datetime(2023, 12, 15, 3, 0, 0, tzinfo=EASTERN_TIME)) == date(2023, 12, 15)
+    assert service_date(datetime(2023, 12, 15, 5, 45, 0, tzinfo=EASTERN_TIME)) == date(2023, 12, 15)
+    assert service_date(datetime(2023, 12, 15, 7, 15, 0, tzinfo=EASTERN_TIME)) == date(2023, 12, 15)
+    assert service_date(datetime(2023, 12, 15, 23, 59, 59, tzinfo=EASTERN_TIME)) == date(2023, 12, 15)
+    assert service_date(datetime(2023, 12, 16, 0, 0, 0, tzinfo=EASTERN_TIME)) == date(2023, 12, 15)
+    assert service_date(datetime(2023, 12, 16, 2, 59, 59, tzinfo=EASTERN_TIME)) == date(2023, 12, 15)
+
+
+def test_edt_vs_est_datetimes():
+    assert service_date(datetime(2023, 11, 5, 23, 59, 59, tzinfo=EASTERN_TIME)) == date(2023, 11, 5)
+    assert service_date(datetime(2023, 11, 6, 0, 0, 0, tzinfo=EASTERN_TIME)) == date(2023, 11, 5)
+    assert service_date(datetime(2023, 11, 6, 1, 0, 0, tzinfo=EASTERN_TIME)) == date(2023, 11, 5)
+    assert service_date(datetime(2023, 11, 6, 2, 0, 0, tzinfo=EASTERN_TIME)) == date(2023, 11, 5)
+    # 3am EST is 4am EDT
+    assert service_date(datetime(2023, 11, 6, 3, 0, 0, tzinfo=EASTERN_TIME)) == date(2023, 11, 6)