README.md

Unit Testing

• Show how to add unit tests to existing project
• Talk about code that is suitable for unit testing
• Anything with logic we can extract out and test as a small indiviudal unit

CurrencyFormatter

class CurrencyFormatterTests: XCTestCase {
    var formatter: CurrencyFormatter!
    
    override func setUp() {
        super.setUp()
        formatter = CurrencyFormatter()
    }
    
    func testBreakDollarsIntoCents() throws {
        let result = formatter.breakIntoDollarsAndCents(929466.23)
        XCTAssertEqual(result.0, "929,466")
        XCTAssertEqual(result.1, "23")
    }
}

Challenge: Have students write a test for checking the balance with zeros.

Solution:

    func testBreakZeroDollarsIntoCents() throws {
        let result = formatter.breakIntoDollarsAndCents(0.00)
        XCTAssertEqual(result.0, "0")
        XCTAssertEqual(result.1, "00")
    }

Another challenge. Write two more test cases:

• one testing our dollarsFormatted func for some amount.
• another for zero amount

    // Challenge: You write
    func testDollarsFormatted() throws {
        let result = formatter.dollarsFormatted(929466.23)
        XCTAssertEqual(result, "$929,466.23")
    }

    // Challenge: You write
    func testZeroDollarsFormatted() throws {
        let result = formatter.dollarsFormatted(0.00)
        XCTAssertEqual(result, "$0.00")
    }

Some overlap of tests is OK.

> git add .
> git commit -m "test: Add unit tests for CurrencyFormatter"

Discussion

• Hopefully you've now got a test of what unit tests are and how they work
• They are a form of automated testing
• But they also affect our design
• You see to make things more testable, you have to write your code in a certain way - more often than not a good one
• Need to extact funcs
• Design pieces into smaller componets
• Because all these make things easier to test
• Tests are also a form of documentation and communication
• When you write a unit test, you are demonstrating the intent behind how something works
• The beauty of this, is this is the documentation is executable.
• And you can run these everytime you make a change or want to verify everything still works
• Often run as part of a continuous integration process which is run everytime someone checks code in

House Keeping

Let's do a little house cleaning and get our login onboarding flow back.

AppDelegate

@main
class AppDelegate: UIResponder, UIApplicationDelegate {
    
    var window: UIWindow?
    let loginViewController = LoginViewController()
    let onboardingViewController = OnboardingContainerViewController()
    let mainViewController = MainViewController()
        
    func application(_ application: UIApplication, didFinishLaunchingWithOptions launchOptions: [UIApplication.LaunchOptionsKey: Any]?) -> Bool {
        
        window = UIWindow(frame: UIScreen.main.bounds)
        window?.makeKeyAndVisible()
        window?.backgroundColor = .systemBackground
                
        loginViewController.delegate = self
        onboardingViewController.delegate = self

        displayLogin()
        return true
    }

    private func displayLogin() {
        setRootViewController(loginViewController)
    }

    private func displayNextScreen() {
        if LocalState.hasOnboarded {
            prepMainView()
            setRootViewController(mainViewController)
        } else {
            setRootViewController(onboardingViewController)
        }
    }
    
    private func prepMainView() {
        mainViewController.setStatusBar()
        UINavigationBar.appearance().isTranslucent = false
        UINavigationBar.appearance().backgroundColor = appColor
    }
}

extension AppDelegate {
    func setRootViewController(_ vc: UIViewController, animated: Bool = true) {
        guard animated, let window = self.window else {
            self.window?.rootViewController = vc
            self.window?.makeKeyAndVisible()
            return
        }

        window.rootViewController = vc
        window.makeKeyAndVisible()
        UIView.transition(with: window,
                          duration: 0.3,
                          options: .transitionCrossDissolve,
                          animations: nil,
                          completion: nil)
    }
}

extension AppDelegate: LoginViewControllerDelegate {
    func didLogin() {
        displayNextScreen()
    }
}

extension AppDelegate: OnboardingContainerViewControllerDelegate {
    func didFinishOnboarding() {
        LocalState.hasOnboarded = true
        prepMainView()
        setRootViewController(mainViewController)
    }
}

extension AppDelegate: LogoutDelegate {
    func didLogout() {
        setRootViewController(loginViewController)
    }
}

Save your work

> git add .
> git commit -m "refactor: General AppDelegate cleanup"

Links that help

• What is an Xcode Target?
• Working with Targets