How do I unit test NSFetchedResultsControllerDelegate (controllerWillChangeContent and controllerDidChangeContent) using Swift

Question

I have the following delegate and I need to test that tableView.beginUpdates() got called. I'm using XCTest and Swift 3. Do you have any ideas or sample code?

extension SomeListController: NSFetchedResultsControllerDelegate {



func controllerWillChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {

    tableView.beginUpdates()

}



func controllerDidChangeContent(_ controller: NSFetchedResultsController<NSFetchRequestResult>) {

    tableView.endUpdates()

}

}

Answer 1

I actually figured it out eventually. The endsUpdates test is pretty much the same pattern.

func test_controllerWillChangeContent_beginsUpdates() {

    class MockTableView: UITableView {

        var gotCalled: Bool = false
        override func beginUpdates() {
            gotCalled = true
        }

    }

    let tableView: MockTableView = MockTableView()
    controller.tableView = tableView

    let _ = controller.view

    controller.controllerWillChangeContent(controller.fetchedResultsControler as! NSFetchedResultsController<NSFetchRequestResult>)

    XCTAssertTrue(tableView.gotCalled)

}