FakeSyncServices.swift

protocol ThingsService {
  func getThings() -> Result<[Thing]>
  func add(thing: Thing) -> Result<Bool>
}

class FakeThingsService: ThingsService {
  private(set) var things: [Thing]
  init(things: [Thing]) {
    self.things = things
  }
  func getThings() -> Result<[Thing]> {
    Thread.sleep(forTimeInterval: 1.0)
    return .result(things)
  }
  func add(thing: Thing) -> Result<Bool> {
    Thread.sleep(forTimeInterval: 1.0)
    if things.contains(thing) {
      return .success(false)
    } else {
      things.append(thing)
      return .success(true)
    }
  }
}