add file io tests

src/icalendar/tests/test_file_io.py

@@ -0,0 +1,100 @@
+import pytest
+from datetime import datetime
+from pathlib import Path
+from icalendar import Calendar, Event, Todo, Journal
+
+
+@pytest.fixture
+def temp_path(tmp_path):
+    """Create a temp directory and change to it for tests"""
+    return tmp_path / "test.ics"
+
+
+@pytest.fixture
+def multiple_calendars_path():
+    """Path to test file containing multiple calendar components"""
+    return Path("src/icalendar/tests/calendars/multiple_calendar_components.ics")
+
+
+def test_from_file_str_path(calendars):
+    """Test reading from file using string path"""
+    path = "src/icalendar/tests/calendars/example.ics"
+    cal = Calendar.from_file(path)
+    assert cal == calendars.example
+
+
+def test_from_file_path_object(calendars):
+    """Test reading from file using Path object"""
+    path = Path("src/icalendar/tests/calendars/example.ics")
+    cal = Calendar.from_file(path)
+    assert cal == calendars.example
+
+
+def test_from_file_multiple(multiple_calendars_path):
+    """Test reading multiple components from a file"""
+    cals = Calendar.from_file(multiple_calendars_path, multiple=True)
+    assert isinstance(cals, list)
+    assert len(cals) > 1
+    assert all(isinstance(cal, Calendar) for cal in cals)
+
+
+def test_from_file_non_existent():
+    """Test attempting to read from non-existent file"""
+    with pytest.raises(FileNotFoundError):
+        Calendar.from_file("non_existent.ics")
+
+
+def test_to_file_str_path(temp_path, calendars):
+    """Test writing to file using string path"""
+    cal = calendars.example
+    cal.to_file(str(temp_path))
+    assert temp_path.exists()
+    # Verify contents by reading back
+    cal2 = Calendar.from_file(temp_path)
+    assert cal == cal2
+
+
+def test_to_file_path_object(temp_path, calendars):
+    """Test writing to file using Path object"""
+    cal = calendars.example
+    cal.to_file(temp_path)
+    assert temp_path.exists()
+    # Verify contents by reading back
+    cal2 = Calendar.from_file(temp_path)
+    assert cal == cal2
+
+
+def test_other_components(temp_path):
+    """Test file I/O with other component types"""
+    components = [Event(), Todo(), Journal()]
+
+    for comp in components:
+        comp.add("summary", "Test")
+        comp.to_file(temp_path)
+        assert temp_path.exists()
+        # Read back and verify it's the correct type
+        comp2 = type(comp).from_file(temp_path)
+        assert isinstance(comp2, type(comp))
+        assert comp == comp2
+
+
+def test_component_roundtrip(temp_path):
+    """Test that a component survives a write/read cycle preserving all data"""
+    # Create a complex calendar with nested components
+    cal = Calendar()
+    event = Event()
+    event.add("summary", "Test Event")
+
+    dt = datetime(2024, 1, 1, 12, 0, 0)
+    event.add("dtstart", dt)
+    cal.add_component(event)
+
+    # Write and read back
+    cal.to_file(temp_path)
+    cal2 = Calendar.from_file(temp_path)
+
+    # Verify equality
+    assert cal == cal2
+    assert len(cal2.subcomponents) == len(cal.subcomponents)
+    assert cal2.subcomponents[0]["summary"] == "Test Event"
+    assert cal2.subcomponents[0]["dtstart"].dt == dt