Testables

Make private properties testable


Keywords
private, swift, test
License
MIT
Install
pod try Testables

Documentation

Testables

Make private properties testable. Be aware of using this project since it is very conceptual.

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
  }
}
#endif

And update the test code:

// when
viewController.username = "devxoul"

// then
let usernameLabel = viewController.testable[\.usernameLabel] //
XCTAssertEqual(usernameLabel.text, "devxoul")

License

Testables is under MIT license. See the LICENSE file for more info.