diff --git a/tests/test_pipeline.py b/tests/test_pipeline.py
new file mode 100644
index 0000000..2f11b26
--- /dev/null
+++ b/tests/test_pipeline.py
@@ -0,0 +1,22 @@
+# tests/test_pipeline.py
+import pytest
+from datetime import datetime
+from your_module import validate_dates, prepare_hours
+
+def test_validate_dates_valid():
+    start, end = validate_dates("01/01/2024", "02/01/2024")
+    assert isinstance(start, datetime)
+    assert isinstance(end, datetime)
+    assert end > start
+
+def test_validate_dates_invalid():
+    with pytest.raises(ValueError):
+        validate_dates("02/01/2024", "01/01/2024")  # end before start
+
+def test_prepare_hours_valid():
+    hours = prepare_hours(["00", "01", "23"])
+    assert all(h in hours for h in ["00", "01", "23"])
+
+def test_prepare_hours_invalid():
+    with pytest.raises(ValueError):
+        prepare_hours(["24"])  # invalid hour