feat: Implement single sync job management and progress tracking

backend/tests/unit/test_sync_manager.py

@@ -0,0 +1,46 @@
+import pytest
+from backend.src.services.sync_manager import CurrentSyncJobManager
+
+
+@pytest.mark.asyncio
+async def test_singleton():
+    manager1 = CurrentSyncJobManager()
+    manager2 = CurrentSyncJobManager()
+    assert manager1 is manager2
+
+
+@pytest.mark.asyncio
+async def test_start_sync():
+    manager = CurrentSyncJobManager()
+    await manager.start_sync("activities")
+    status = await manager.get_current_sync_status()
+    assert status.status == "in_progress"
+    assert status.job_type == "activities"
+
+
+@pytest.mark.asyncio
+async def test_start_sync_while_active():
+    manager = CurrentSyncJobManager()
+    await manager.start_sync("activities")
+    with pytest.raises(RuntimeError):
+        await manager.start_sync("workouts")
+
+
+@pytest.mark.asyncio
+async def test_complete_sync():
+    manager = CurrentSyncJobManager()
+    await manager.start_sync("activities")
+    await manager.complete_sync()
+    status = await manager.get_current_sync_status()
+    assert status.status == "completed"
+    assert status.progress == 1.0
+
+
+@pytest.mark.asyncio
+async def test_fail_sync():
+    manager = CurrentSyncJobManager()
+    await manager.start_sync("activities")
+    await manager.fail_sync("Test error")
+    status = await manager.get_current_sync_status()
+    assert status.status == "failed"
+    assert status.error_message == "Test error"