Testing tableview.reloadData() - swift

Question

while using a MockTableView this code still not calling reloadData() from the mock,
please i wanna know what is wrong here.
following this book: Test-Driven IOS Development with Swift 4 - Third Edition
page 164, i was as an exercise
full code repo - on github
ItemListViewController.swift
import UIKit
class ItemListViewController: UIViewController, ItemManagerSettable {
#IBOutlet var tableView: UITableView!
#IBOutlet var dataProvider: (UITableViewDataSource & UITableViewDelegate &
ItemManagerSettable)!
var itemManager: ItemManager?
override func viewDidLoad() {
super.viewDidLoad()
itemManager = ItemManager()
dataProvider.itemManager = itemManager
tableView.dataSource = dataProvider
tableView.delegate = dataProvider
}
override func viewWillAppear(_ animated: Bool) {
super.viewWillAppear(animated)
tableView.reloadData()
}
#IBAction func addItem(_ sender: UIBarButtonItem) {
if let nextViewController =
storyboard?.instantiateViewController(
withIdentifier: "InputViewController")
as? InputViewController {
nextViewController.itemManager = itemManager
present(nextViewController, animated: true, completion: nil)
}
}
}
ItemListViewControllerTest.swift
import XCTest
#testable import ToDo
class ItemListViewControllerTest: XCTestCase {
var sut: ItemListViewController!
var addButton: UIBarButtonItem!
var action: Selector!
override func setUpWithError() throws {
let storyboard = UIStoryboard(name: "Main", bundle: nil)
let vc = storyboard.instantiateViewController(withIdentifier:
"ItemListViewController")
sut = vc as? ItemListViewController
addButton = sut.navigationItem.rightBarButtonItem
action = addButton.action
UIApplication.shared.keyWindow?.rootViewController = sut
sut.loadViewIfNeeded()
}
override func tearDownWithError() throws {}
func testItemListVC_ReloadTableViewWhenAddNewTodoItem() {
let mockTableView = MocktableView()
sut.tableView = mockTableView
guard let addButton = sut.navigationItem.rightBarButtonItem else{
XCTFail()
return
}
guard let action = addButton.action else{
XCTFail()
return
}
sut.performSelector(onMainThread: action, with: addButton, waitUntilDone: true)
guard let inputViewController = sut.presentedViewController as?
InputViewController else{
XCTFail()
return
}
inputViewController.titleTextField.text = "Test Title"
inputViewController.save()
XCTAssertTrue(mockTableView.calledReloadData)
}
}
extension ItemListViewControllerTest{
class MocktableView: UITableView{
var calledReloadData: Bool = false
override func reloadData() {
calledReloadData = true
super.reloadData()
}
}
}

Answer 1

You inject a MockTableview Then you call loadViewIfNeeded(). But because this view controller is storyboard-based and the table view is an outlet, the actual table view is loaded at this time. This replaces your MockTableview.
One solution is:
Call loadViewIfNeeded() first
Inject the MockTableview to replace the actual table view
Call viewDidLoad() directly. Even though loadViewIfNeeded() already called it, we need to repeat it now that we have a different tableview in place.
Another possible solution:
Avoid MockTableview completely. Continue to use a real table view. You can test whether it reloads data by checking whether the number of rows matches the changed data.
Yet another solution:
Avoid storyboards. You can do this with plain XIBs (but these lack table view prototype cells) or programmatically.
By the way, I see all your tearDownWithError() implementations are empty. Be sure to tear down everything you set up. Otherwise you will end up with multiple instances of your system under test alive at the same time. I explain there here: https://qualitycoding.org/xctestcase-teardown/