feat: schedule periodic user synchronization

tests/sync/test_scheduler.py

@@ -0,0 +1,42 @@
+import asyncio
+
+import pytest
+
+from app.sync.scheduler import SyncScheduler
+
+
+class FakeSyncManager:
+    def __init__(self, results=None) -> None:
+        self.results = results if results is not None else []
+        self.calls = 0
+
+    async def sync_all_enabled(self):
+        self.calls += 1
+        if self.results and isinstance(self.results[0], Exception):
+            raise self.results[0]
+        return list(self.results)
+
+
+@pytest.mark.asyncio
+async def test_scheduler_calls_sync_all_and_survives_failure() -> None:
+    fake = FakeSyncManager(results=[RuntimeError("one user failed")])
+    scheduler = SyncScheduler(fake, interval_seconds=0.01)
+    await scheduler.start()
+    await asyncio.sleep(0.035)
+    await scheduler.stop()
+    assert fake.calls >= 2
+    assert scheduler.last_tick is not None
+
+
+@pytest.mark.asyncio
+async def test_scheduler_stop_cancels_the_loop() -> None:
+    fake = FakeSyncManager()
+    scheduler = SyncScheduler(fake, interval_seconds=0.01)
+    await scheduler.start()
+    await asyncio.sleep(0.035)
+    await scheduler.stop()
+
+    assert scheduler._task is None
+    calls_after_stop = fake.calls
+    await asyncio.sleep(0.05)
+    assert fake.calls == calls_after_stop