Is it possible to init and load only custom cell and test outlets?
My ViewController has TableView with separated dataSource ( which is subclass of custom data source ). So it's kinda tricky to create cell using all of those.
Custom cell has only a couple of labels and config method for updating them from object, so if loaded, testing would be easy.
It is possible to write a unit test for custom UITableViewCell that will test its outlets and any other functionality included in it. The following sample demonstrates this:
class TestItemTableViewCell: XCTestCase {
var tableView: UITableView!
private var dataSource: TableViewDataSource!
private var delegate: TableViewDelegate!
override func setUp() {
tableView = UITableView(frame: CGRect(x: 0, y: 0, width: 200, height: 400), style: .plain)
let itemXib = UINib.init(nibName: "ItemTableViewCell",
bundle: nil)
tableView.register(itemXib,
forCellReuseIdentifier: "itemCell")
dataSource = TableViewDataSource()
delegate = TableViewDelegate()
tableView.delegate = delegate
tableView.dataSource = dataSource
}
func testAwakeFromNib() {
let indexPath = IndexPath(row: 0, section: 0)
let itemCell = createCell(indexPath: indexPath)
// Write assertions for things you expect to happen in
// awakeFromNib() method.
}
}
extension TestItemTableViewCell {
func createCell(indexPath: IndexPath) -> ItemTableViewCell {
let cell = dataSource.tableView(tableView, cellForRowAt: indexPath) as! ItemTableViewCell
XCTAssertNotNil(cell)
let view = cell.contentView
XCTAssertNotNil(view)
return cell
}
}
private class TableViewDataSource: NSObject, UITableViewDataSource {
var items = [Item]()
override init() {
super.init()
// Initialize model, i.e. create&add object in items.
}
func tableView(_ tableView: UITableView, numberOfRowsInSection section: Int) -> Int {
return items.count
}
func tableView(_ tableView: UITableView, cellForRowAt indexPath: IndexPath) -> UITableViewCell {
let cell = tableView.dequeueReusableCell(withIdentifier: "itemCell",
for: indexPath)
return cell
}
}
private class TableViewDelegate: NSObject, UITableViewDelegate {
}
This approach mimics the way UITableViewCells are created/reused at runtime. The same methods get called, e.g. awakeFromNib, IBOutlets initialized, etc. I am sure you can even test the sizing of the cell (e.g. height) even though I haven't tried that yet. Note that having a view model where the "visualization" logic of your model object is contained is a good & modular approach and makes it easier to unit test parts of the code (as described in another answer above). However, with a unit test for a view model object, you cannot test the entire lifecycle of a UITableViewCell.