polac24

func testDelegateKeepsWeakReference() {
    // Arrange
    let sut = MasterClass()
    // Act
    let listener = weaklyScoped(MasterListener()) {
        sut.add($0)
    }
    // Assert
    XCTAssertNil(listener)
}

polac24

func weaklyScoped<T: AnyObject>(_ v: @autoclosure () -> T, action: (T) throws -> ()) rethrows -> T? {
    weak var weakValue: T?
    do { // optionally autoreleasepool
        let value = v()
        try action(value)
        weakValue = value
    }
    return weakValue
}

polac24

func weaklyScopedNaive<T: AnyObject>(_ v: T, action: (inout T) -> ()) -> T? {
    weak var weakValue: T?
    do {
        action(&v)
        weakValue = v
    }
    return weakValue
}

polac24

func with<T>(x: T, _ f: (inout T) -> Void) -> T {
    var value = x
    f(&value)
    return value
}

polac24

func testListenerKeptWeakReferenceUsingTeardown() {
    // Arrange
    let sut = MasterClass()
    let listener = MasterListener()
    // Act
    sut.add(listener)
    // Assert
    addTeardownBlock { [weak listener] in
        XCTAssertNil(listener)
    }

polac24

func testListenerKeptWithWeakReference() {
    // Arrange
    let sut = MasterClass()
    var listener: MasterClassListener? = MasterListener()
    weak var weakListener = listener
    // Act
    sut.add(listener!)
    listener = nil
    // Assert
    XCTAssertNil(weakListener)

polac24

func testListenerIsKeeptWithWeakReference() {
    // Arrange
    let sut = MasterClass()
    weak var weakListener: MasterClassListener?
    do {
        let listener = MasterListener()
        weakListener = listener
    // Act
        sut.add(listener)
    }

polac24

func stub<T>(of v: T) -> T {
    return nil!
}

class DatabaseStub: Database {
    lazy var addUserAction = stub(of: addUser)
    func addUser(name: String) -> Bool {
        return addUserAction(name)
    }
}

polac24

protocol Loader{
    func load(_ url: @autoclosure ()->(URL), completion: @escaping (URLResponse)->()) throws -> CancelToken
}

// Before
class LoaderStub: Loader {
    var loadAction: ((@autoclosure () -> (URL), (URLResponse) -> ()) throws -> CancelToken)?
    func load(_ url: @autoclosure...){...}
}

polac24

class DatabaseStub {
    lazy var addUserAction = asNil(addUser)
    func addUser(name: String) -> Bool {
        return addUserAction(name) ?? false
    }
}