test: create_calendar raises if required columns not present

tests/gtfs/test_calendar.py

@@ -0,0 +1,21 @@
+"""Test calendar utilities."""
+import pytest
+
+import pandas as pd
+
+from transport_performance.gtfs.calendar import create_calendar_from_dates
+
+
+class TestCreateCalendarFromDates(object):
+    """Tests for create_calendar_from_dates."""
+
+    def test_create_calendar_from_dates_defence(self):
+        """Test defensive checks for create_calendar_from_dates."""
+        with pytest.raises(TypeError, match=".DataFrame'>. Got <class 'int'>"):
+            create_calendar_from_dates(calendar_dates=1)
+        with pytest.raises(
+            IndexError, match="service_id' is not a column in the dataframe."
+        ):
+            create_calendar_from_dates(
+                calendar_dates=pd.DataFrame({"foo": 0}, index=[0])
+            )