diff --git a/tests/test_agenda.py b/tests/test_agenda.py
index fd5ce5d..51d6643 100644
--- a/tests/test_agenda.py
+++ b/tests/test_agenda.py
@@ -1,3 +1,5 @@
+"""Tests for agenda."""
+
 import datetime
 from decimal import Decimal
 
@@ -15,63 +17,63 @@ from agenda import (
 
 
 @pytest.fixture
-def mock_today():
-    # Mock the current date for testing purposes
+def mock_today() -> datetime.date:
+    """Mock the current date for testing purposes."""
     return datetime.date(2023, 10, 5)
 
 
 @pytest.fixture
-def mock_now():
-    # Mock the current date and time for testing purposes
+def mock_now() -> datetime.datetime:
+    """Mock the current date and time for testing purposes."""
     return datetime.datetime(2023, 10, 5, 12, 0, 0)
 
 
-def test_next_uk_mothers_day(mock_today):
-    # Test next_uk_mothers_day function
+def test_next_uk_mothers_day(mock_today: datetime.date) -> None:
+    """Test next_uk_mothers_day function."""
     next_mothers_day = next_uk_mothers_day(mock_today)
     assert next_mothers_day == datetime.date(2024, 4, 21)
 
 
-def test_next_uk_fathers_day(mock_today):
-    # Test next_uk_fathers_day function
+def test_next_uk_fathers_day(mock_today: datetime.date) -> None:
+    """Test next_uk_fathers_day function."""
     next_fathers_day = next_uk_fathers_day(mock_today)
     assert next_fathers_day == datetime.date(2024, 6, 21)
 
 
-def test_get_next_timezone_transition(mock_now) -> None:
-    # Test get_next_timezone_transition function
+def test_get_next_timezone_transition(mock_now: datetime.date) -> None:
+    """Test get_next_timezone_transition function."""
     next_transition = get_next_timezone_transition(mock_now, "Europe/London")
     assert next_transition == datetime.date(2023, 10, 29)
 
 
-def test_get_next_bank_holiday(mock_today) -> None:
-    # Test get_next_bank_holiday function
+def test_get_next_bank_holiday(mock_today: datetime.date) -> None:
+    """Test get_next_bank_holiday function."""
     next_holiday = get_next_bank_holiday(mock_today)[0]
     assert next_holiday.date == datetime.date(2023, 12, 25)
     assert next_holiday.title == "Christmas Day"
 
 
-def test_get_gbpusd(mock_now):
-    # Test get_gbpusd function
+def test_get_gbpusd(mock_now: datetime.datetime) -> None:
+    """Test get_gbpusd function."""
     gbpusd = get_gbpusd()
     assert isinstance(gbpusd, Decimal)
     # You can add more assertions based on your specific use case.
 
 
-def test_next_economist(mock_today):
-    # Test next_economist function
+def test_next_economist(mock_today: datetime.date) -> None:
+    """Test next_economist function."""
     next_publication = next_economist(mock_today)
     assert next_publication == datetime.date(2023, 10, 5)
 
 
-def test_uk_financial_year_end():
-    # Test uk_financial_year_end function
+def test_uk_financial_year_end() -> None:
+    """Test uk_financial_year_end function."""
     financial_year_end = uk_financial_year_end(datetime.date(2023, 4, 1))
     assert financial_year_end == datetime.date(2023, 4, 5)
 
 
-def test_timedelta_display():
-    # Test timedelta_display function
+def test_timedelta_display() -> None:
+    """Test timedelta_display function."""
     delta = datetime.timedelta(days=2, hours=5, minutes=30)
     display = timedelta_display(delta)
     assert display == "  2 days   5 hrs  30 mins"