Recommended way to test mappings

[ogezue]

In my project I have written some model classes that fetch data via Alamofire, Objectmapper and Realm. Sometimes a backend developer changes the REST-interface or a dog walks across my keyboard, so that my mapping breaks.

I would like to increase my test coverage and detect if my mapping doesn't fit to the REST-service anymore. What would be the best approach to test this?

Here is a method thats would be great to have tested:

 func fetchOverviewItemList(successHandler: List<OverviewItem> -> (), errorHandler: (ErrorType?) -> ()){

        //fetch existing objects from DB
        let overviewItemsAsList = List<OverviewItem>()
        overviewItemsAsList.appendContentsOf(self.realm.objects(OverviewItem))
        successHandler(overviewItemsAsList)

        AlamofireManager.Configured
            .request(.GET, URLs.sharedInstance.overviewItemsUrl())
            .responseJSON{response in log.verbose("response: \(response.result.value)")}
            .responseArray("sefInfos") { (response: Response<[OverviewItem], NSError>) in

                if let error = response.result.error{
                    log.error("Error: \(error.localizedDescription)")
                    errorHandler(error)
                    return
                }

                if let overviewItemsArray = response.result.value{

                    //remove orphans
                    self.deleteOrphans(overviewItemsAsList, fetchedData: overviewItemsArray)


                    //update objects from service
                    overviewItemsAsList.removeAll()
                    overviewItemsAsList.appendContentsOf(overviewItemsArray)
                    successHandler(overviewItemsAsList)

                    do{
                        try self.realm.write{
                            self.realm.add(overviewItemsAsList, update: true)
                        }
                    }
                    catch let err as NSError {
                        log.error("Error with realm: \(err.localizedDescription)")
                    }
                }
        }
    }

[tristanhimmelman]

Closing this as I answered your same question in the ObjectMapper project