Core: Fixed potential out-of-sync issue if user cancels while in the middle of delta step

CliClient/tests/synchronizer.js

@@ -606,5 +606,25 @@ describe('Synchronizer', function() {
 
 		done();
 	});
+
+	it('items should be downloaded again when user cancels in the middle of delta operation', async (done) => {
+		let folder1 = await Folder.save({ title: "folder1" });
+		let note1 = await Note.save({ title: "un", is_todo: 1, parent_id: folder1.id });
+		await synchronizer().start();
+
+		await switchClient(2);
+
+		synchronizer().debugFlags_ = ['cancelDeltaLoop2'];		
+		let context = await synchronizer().start();
+		let notes = await Note.all();
+		expect(notes.length).toBe(0);
+
+		synchronizer().debugFlags_ = [];
+		await synchronizer().start({ context: context });
+		notes = await Note.all();
+		expect(notes.length).toBe(1);
+
+		done();
+	});
 	
 });