Testables
Make private properties testable.
Background
Let's assume that there is a class named ProfileViewController. This class has a property username which sets usernameLabel.text when the new value is assigned. Unfortunately, we cannot write an unit test because usernameLabel is a private property.
ProfileViewController.swift
class ProfileViewController {
var username: String? {
didSet {
self.usernameLabel.text = self.username
}
}
private let usernameLabel = UILabel()
}ProfileViewControllerTests.swift
// when
viewController.username = "devxoul"
// then
let usernameLabel = viewController.usernameLabel // 🚫 private
XCTAssertEqual(usernameLabel.text, "devxoul")Solution
Testables provides a generic way to expose private properties using Swift KeyPath.
Add the lines below to ProfileViewController.swift:
#if DEBUG
import Testables
extension ProfileViewController: Testable {
final class TestableKeys: TestableKey<Self> {
let usernameLabel = \Self.usernameLabel
}
}
#endifAnd update the test code:
// when
viewController.username = "devxoul"
// then
let usernameLabel = viewController.testables[\.usernameLabel] // ✅
XCTAssertEqual(usernameLabel.text, "devxoul")License
Testables is under MIT license. See the LICENSE file for more info.