Add comprehensive test coverage for 8 modules

Increases overall test coverage from 53% to 56% by adding tests for:
- accommodation.py (60% → 100%)
- birthday.py (24% → 100%)
- calendar.py (19% → 100%)
- carnival.py (33% → 100%)
- domains.py (75% → 100%)
- events_yaml.py (50% → 96%)
- fx.py (14% → 21% for tested functions)
- sun.py (55% → 100%)

🤖 Generated with [Claude Code](https://claude.ai/code)

Co-Authored-By: Claude <noreply@anthropic.com>

tests/test_carnival.py

@@ -0,0 +1,125 @@
+"""Tests for carnival functionality."""
+
+from datetime import date
+
+from agenda.carnival import rio_carnival_events
+from agenda.event import Event
+
+
+class TestRioCarnivalEvents:
+    """Test the rio_carnival_events function."""
+
+    def test_carnival_events_single_year(self) -> None:
+        """Test getting carnival events for a single year."""
+        # 2024 Easter is March 31, so carnival should be around Feb 9-14
+        start_date = date(2024, 1, 1)
+        end_date = date(2024, 12, 31)
+        
+        events = rio_carnival_events(start_date, end_date)
+        
+        assert len(events) == 1
+        event = events[0]
+        assert event.name == "carnival"
+        assert event.title == "Rio Carnival"
+        assert event.url == "https://en.wikipedia.org/wiki/Rio_Carnival"
+        assert event.date.year == 2024
+        assert event.end_date is not None
+        assert event.end_date.year == 2024
+        # Should be about 51 days before Easter (around early-mid February)
+        assert event.date.month == 2
+        assert event.end_date.month == 2
+
+    def test_carnival_events_multiple_years(self) -> None:
+        """Test getting carnival events for multiple years."""
+        start_date = date(2023, 1, 1)
+        end_date = date(2025, 12, 31)
+        
+        events = rio_carnival_events(start_date, end_date)
+        
+        # Should have carnival for 2023, 2024, and 2025
+        assert len(events) == 3
+        
+        years = [event.date.year for event in events]
+        assert sorted(years) == [2023, 2024, 2025]
+        
+        # All events should be carnival events
+        for event in events:
+            assert event.name == "carnival"
+            assert event.title == "Rio Carnival"
+            assert event.url == "https://en.wikipedia.org/wiki/Rio_Carnival"
+
+    def test_carnival_events_no_overlap(self) -> None:
+        """Test when date range doesn't overlap with carnival."""
+        # Choose a range that's unlikely to include carnival (summer)
+        start_date = date(2024, 6, 1)
+        end_date = date(2024, 8, 31)
+        
+        events = rio_carnival_events(start_date, end_date)
+        
+        assert events == []
+
+    def test_carnival_events_partial_overlap_start(self) -> None:
+        """Test when carnival start overlaps with date range."""
+        # 2024 carnival should be around Feb 9-14
+        start_date = date(2024, 2, 10)  # Might overlap with carnival start
+        end_date = date(2024, 2, 15)
+        
+        events = rio_carnival_events(start_date, end_date)
+        
+        # Should include carnival if there's any overlap
+        if events:
+            assert len(events) == 1
+            assert events[0].name == "carnival"
+
+    def test_carnival_events_partial_overlap_end(self) -> None:
+        """Test when carnival end overlaps with date range."""
+        # 2024 carnival should be around Feb 9-14
+        start_date = date(2024, 2, 12)
+        end_date = date(2024, 2, 20)  # Might overlap with carnival end
+        
+        events = rio_carnival_events(start_date, end_date)
+        
+        # Should include carnival if there's any overlap
+        if events:
+            assert len(events) == 1
+            assert events[0].name == "carnival"
+
+    def test_carnival_dates_relative_to_easter(self) -> None:
+        """Test that carnival dates are correctly calculated relative to Easter."""
+        start_date = date(2024, 1, 1)
+        end_date = date(2024, 12, 31)
+        
+        events = rio_carnival_events(start_date, end_date)
+        
+        assert len(events) == 1
+        event = events[0]
+        
+        # Carnival should be 5 days long
+        duration = (event.end_date - event.date).days + 1
+        assert duration == 6  # 51 days before to 46 days before Easter (6 days total)
+        
+        # Both dates should be in February for 2024
+        assert event.date.month == 2
+        assert event.end_date.month == 2
+        
+        # End date should be after start date
+        assert event.end_date > event.date
+
+    def test_carnival_events_empty_date_range(self) -> None:
+        """Test with empty date range."""
+        start_date = date(2024, 6, 15)
+        end_date = date(2024, 6, 10)  # End before start
+        
+        events = rio_carnival_events(start_date, end_date)
+        
+        # Should return empty list for invalid range
+        assert events == []
+
+    def test_carnival_events_same_start_end_date(self) -> None:
+        """Test with same start and end date."""
+        # Pick a date that's definitely not carnival
+        test_date = date(2024, 7, 15)
+        
+        events = rio_carnival_events(test_date, test_date)
+        
+        assert events == []