test: add test for generate_conflicts in services

program/tests/test_services.py

+from datetime import datetime
+
+import pytest
+
+from django.utils.timezone import make_aware
+from program.models import TimeSlot
+from program.services import generate_conflicts
+from program.tests.factories import TimeslotFactory
+
+pytestmark = pytest.mark.django_db
+
+
+def create_timeslot(once_schedule) -> None:
+    """creates and saves a timeslot instance for a "once" schedule for 2024-05-21 16:00-18:00."""
+
+    TimeslotFactory.create(
+        start=make_aware(datetime(2024, 5, 21, 16, 0)),
+        end=make_aware(datetime(2024, 5, 21, 18, 0)),
+        schedule=once_schedule,
+    )
+
+
+def build_timeslot(once_schedule, start: tuple[int, int], end: tuple[int, int]) -> TimeSlot:
+    """builds and returns a timeslot object for a "once" schedule for 2020-05-21 `start`-`end`."""
+
+    start_hour, start_minute = start
+    end_hour, end_minute = end
+
+    return TimeslotFactory.build(
+        start=make_aware(datetime(2024, 5, 21, start_hour, start_minute)),
+        end=make_aware(datetime(2024, 5, 21, end_hour, end_minute)),
+        schedule=once_schedule,
+    )
+
+
+def test_generate_conflicts_partially_overlapping_end(once_schedule):
+    create_timeslot(once_schedule)  # 16:00 - 18:00
+    # Partly overlapping timeslot: start before existing start, end before existing end
+    timeslots = [build_timeslot(once_schedule, start=(15, 30), end=(17, 30))]
+
+    conflicts = generate_conflicts(timeslots)
+
+    assert "theirs-end" and "ours-end" in conflicts["projected"][0]["solution_choices"]
+
+
+def test_generate_conflicts_partially_overlapping_start(once_schedule):
+    create_timeslot(once_schedule)  # 16:00 - 18:00
+    # Partly overlapping timeslots: start after existing start, end after existing end
+    timeslots = [build_timeslot(once_schedule, start=(16, 30), end=(18, 30))]
+
+    conflicts = generate_conflicts(timeslots)
+
+    assert "theirs-start" and "ours-start" in conflicts["projected"][0]["solution_choices"]
+
+
+def test_generate_conflicts_fully_overlapping_theirs(once_schedule):
+    create_timeslot(once_schedule)  # 16:00 - 18:00
+    # Fully overlapping timeslot: start before existing start, end after existing end
+    timeslots = [build_timeslot(once_schedule, start=(15, 30), end=(18, 30))]
+
+    conflicts = generate_conflicts(timeslots)
+
+    assert (
+        "theirs-end"
+        and "theirs-start"
+        and "theirs-both" in conflicts["projected"][0]["solution_choices"]
+    )
+
+
+def test_generate_conflicts_fully_overlapping_ours(once_schedule):
+    create_timeslot(once_schedule)  # 16:00 - 18:00
+    # Fully overlapping: start after existing start, end before existing end
+    timeslots = [build_timeslot(once_schedule, start=(16, 30), end=(17, 30))]
+
+    conflicts = generate_conflicts(timeslots)
+
+    assert (
+        "ours-end"
+        and "ours-start"
+        and "ours-both" in conflicts["projected"][0]["solution_choices"]
+    )
+
+
+def test_generate_conflicts_overlapping_ours_theirs(once_schedule):
+    create_timeslot(once_schedule)  # 16:00 - 18:00
+    # Fully overlapping: starts and ends are equal
+    timeslots = [build_timeslot(once_schedule, start=(16, 0), end=(18, 0))]
+
+    conflicts = generate_conflicts(timeslots)
+
+    assert "ours" and "theirs" in conflicts["projected"][0]["solution_choices"]