Testing a UITableView in a UIViewController programatically instantiated - swift

Question

I want to inject my data manager into my view controller and test it.
The ViewController:
class ViewController: UIViewController {
#IBOutlet weak var tableView: UITableView!
var alert: AlertViewController?
var coreDataManager: CoreDataManagerProtocol?
init(coreDataManager: CoreDataManagerProtocol) {
self.coreDataManager = coreDataManager
super.init(nibName: nil, bundle: nil)
}
required init?(coder aDecoder: NSCoder) {
super.init(coder: aDecoder)
self.coreDataManager = CoreDataManager()
}
override func viewDidLoad() {
super.viewDidLoad()
tableView.register(UITableViewCell.self, forCellReuseIdentifier: "Cell")
}
#IBAction func addItem(_ sender: Any) {
alert = UIStoryboard(name: Constants.alertStoryBoard, bundle: nil).instantiateViewController(withIdentifier: Constants.alerts.mainAlert) as? AlertViewController
alert?.title = "Enter your task"
alert?.presentToWindow()
alert?.delegate = self
}
}
extension ViewController: UITableViewDataSource {
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return coreDataManager?.getTasks().count ?? 0
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let data = coreDataManager?.getTasks()[indexPath.row]
let cell = tableView.dequeueReusableCell(withIdentifier: "Cell", for: indexPath)
cell.textLabel?.text = data?.value(forKey: Constants.entityNameAttribute) as? String
return cell
}
}
I want to test this through injecting at mock into the view controller:
class CoreDataManagerMock: CoreDataManagerProtocol {
var storeCordinator: NSPersistentStoreCoordinator!
var managedObjectContext: NSManagedObjectContext!
var managedObjectModel: NSManagedObjectModel!
var store: NSPersistentStore!
func getTasks() -> [NSManagedObject] {
managedObjectModel = NSManagedObjectModel.mergedModel(from: nil)
storeCordinator = NSPersistentStoreCoordinator(managedObjectModel: managedObjectModel)
do {
store = try storeCordinator.addPersistentStore(
ofType: NSInMemoryStoreType, configurationName: nil, at: nil, options: nil)
} catch {
// catch failure here
}
managedObjectContext = NSManagedObjectContext(concurrencyType: .mainQueueConcurrencyType)
managedObjectContext.persistentStoreCoordinator = storeCordinator
var localTasks = [NSManagedObject]()
let entityOne = NSEntityDescription.insertNewObject(forEntityName: Constants.entityName, into: managedObjectContext)
entityOne.setValue(false, forKey: Constants.entityCompletedattribute)
entityOne.setValue("Enter your task", forKey: Constants.entityNameAttribute)
localTasks.append(entityOne)
return localTasks
}
func save(task: String) {
//
}
}
But I'm struggling to test this.
I can't request a cell as I'm not instantiating from the Storyboard (and I can't, since I need to inject the mock core manager.
In every test I try to run tableView resolves to nil
Here is my attempt, thinking I can test my cellForRowAt function directly:
func testtv() {
let CDM = CoreDataManagerMock()
let viewController = ViewController(coreDataManager: CDM)
viewController.tableView.register(UITableViewCell.self, forCellReuseIdentifier: "Cell")
viewController.tableView(UITableViewMock(), cellForRowAt: IndexPath(row: 0, section: 0))
let actualCell = viewController.tableView?.cellForRow(at: IndexPath(row: 0, section: 0) )
let test = viewController.tableView(UITableViewMock(), cellForRowAt: IndexPath(row: 0, section: 0))
XCTAssertEqual(actualCell?.textLabel?.text, actualCell?.textLabel?.text)
}
But as tableView is nil is nil so I can't register the cell. How can I test cellForRow(at: when I inject my dependency as above?

Answer 1

How I did testing with UIStoryboard instantiated UIViewControllers was by doing this.
// STEP 1
// instantiate the storyboard
let storyboard = UIStoryboard(name: "SomeStoryboard", bundle: nil)
// STEP 2
// instantiate the UIViewController using the storyboard
let sampleViewController = storyboard.instantiateViewController(withIdentifier: "SampleViewController") as! SampleViewController
// STEP 3
// set the properties you need to set
sampleViewController.xxxxx = "foo"
sampleViewController.yyyyy = "bar"
// STEP 4
// call the view so the ui objects would be instantiated
// not doing this would cause a crash
// this also calls `viewDidLoad()`
_ = sampleViewController.view
So in your case since this is how the code would look like:
func testtv() {
let storyboard = UIStoryboard(name: "INSERT STORYBOARD NAME HERE", bundle: nil)
let viewController = storyboard.instantiateViewController(withIdentifier: "ViewController") as! ViewController
viewController.coreDataManager = CoreDataManagerMock()
_ = viewController.view
// I'm not sure about the code below this comment
// but the above code should work
viewController.tableView(UITableViewMock(), cellForRowAt: IndexPath(row: 0, section: 0))
let actualCell = viewController.tableView?.cellForRow(at: IndexPath(row: 0, section: 0) )
let test = viewController.tableView(UITableViewMock(), cellForRowAt: IndexPath(row: 0, section: 0))
XCTAssertEqual(actualCell?.textLabel?.text, actualCell?.textLabel?.text)
}
ViewController
Why this is, is because calling instantiateViewController(withIdentifier: _) uses init?(coder aDecoder: NSCoder)
You can remove this snippet below because you don't need it and it won't work since the UIViewController you're instantiating is from a storyboard.
init(coreDataManager: CoreDataManagerProtocol) {
self.coreDataManager = coreDataManager
super.init(nibName: nil, bundle: nil)
}
What you could do instead is create a static method to instantiate your UIViewController with the parameters you need. Example:
class SomeViewController: UIViewController {
var someObject: SomeObject!
static func instantiate(someObject: SomeObject) -> SomeViewController {
let storyboard = UIStoryboard(name: "SomeStoryboard", bundle: nil)
let viewController = storyboard.instantiateViewController(withIdentifier: "SomeViewController")
viewController.someObject = someObject
return viewController
}
}
// usage
let vc = SomeViewController.instantiate(someObject: SomeObject())
// or
let vc: SomeViewController = .instantiate(someObject: SomeObject())