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zradkezradke
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Vend preferredContentSize through the DescribedViewController
Because the `DescribedViewController` wraps all view controllers used in workflows, if it does not vend its current child's `preferredContentSize`, it will be lost. This makes it very difficult to create dynamic workflows that rely on self-sizing view controllers without introducing workarounds to have the children communicate their intended size to the parent, or by removing the convenience of the `DescribedViewController` entirely. This change solves the issue by having the `DescribedViewController` update its own `preferredContentSize` to match whatever the `currentViewController` is, and when that child's size changes.
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‎swift/WorkflowUI/Sources/ViewControllerDescription/DescribedViewController.swift

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@@ -52,6 +52,7 @@ public final class DescribedViewController: UIViewController {
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view.addSubview(currentViewController.view)
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currentViewController.view.frame = view.bounds
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currentViewController.didMove(toParent: self)
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preferredContentSize = currentViewController.preferredContentSize
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}
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}
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}
@@ -66,6 +67,7 @@ public final class DescribedViewController: UIViewController {
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addChild(currentViewController)
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view.addSubview(currentViewController.view)
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currentViewController.didMove(toParent: self)
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preferredContentSize = currentViewController.preferredContentSize
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}
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public override func viewDidLayoutSubviews() {
@@ -93,6 +95,16 @@ public final class DescribedViewController: UIViewController {
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return currentViewController.supportedInterfaceOrientations
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}
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public override func preferredContentSizeDidChange(forChildContentContainer container: UIContentContainer) {
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super.preferredContentSizeDidChange(forChildContentContainer: container)
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guard
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(container as? UIViewController) == currentViewController,
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container.preferredContentSize != preferredContentSize
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else { return }
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preferredContentSize = container.preferredContentSize
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}
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}
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#endif

‎swift/WorkflowUI/Tests/DescribedViewControllerTests.swift

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@@ -0,0 +1,318 @@
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//
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// DescribedViewControllerTests.swift
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// WorkflowUITests
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//
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// Created by Zachary Radke on 3/30/20.
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//
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#if canImport(UIKit)
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import XCTest
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import ReactiveSwift
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import Workflow
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@testable import WorkflowUI
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fileprivate enum TestScreen: Screen, Equatable {
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case counter(Int)
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case message(String)
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func viewControllerDescription(environment: ViewEnvironment) -> ViewControllerDescription {
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switch self {
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case let .counter(count):
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return ViewControllerDescription(
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build: { CounterViewController(count: count) },
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update: { $0.count = count }
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)
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case let .message(message):
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return ViewControllerDescription(
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build: { MessageViewController(message: message) },
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update: { $0.message = message }
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)
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}
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}
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}
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fileprivate class ContainerViewController: UIViewController {
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let describedViewController: DescribedViewController
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var preferredContentSizeSignal: Signal<CGSize, Never> { return signal.skipRepeats() }
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private let (signal, sink) = Signal<CGSize, Never>.pipe()
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init(describedViewController: DescribedViewController) {
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self.describedViewController = describedViewController
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super.init(nibName: nil, bundle: nil)
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}
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@available(*, unavailable) required init?(coder: NSCoder) {
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fatalError("init(coder:) has not been implemented")
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}
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override func viewDidLoad() {
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super.viewDidLoad()
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addChild(describedViewController)
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describedViewController.view.frame = view.bounds
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describedViewController.view.autoresizingMask = [.flexibleWidth, .flexibleHeight]
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view.addSubview(describedViewController.view)
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describedViewController.didMove(toParent: self)
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}
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override func preferredContentSizeDidChange(forChildContentContainer container: UIContentContainer) {
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guard container === describedViewController else { return }
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sink.send(value: container.preferredContentSize)
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}
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}
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fileprivate class CounterViewController: UIViewController {
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var count: Int {
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didSet {
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preferredContentSize.width = CGFloat(count * 10)
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}
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}
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init(count: Int) {
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self.count = count
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super.init(nibName: nil, bundle: nil)
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preferredContentSize.width = CGFloat(count * 10)
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}
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@available(*, unavailable) required init?(coder: NSCoder) {
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fatalError("init(coder:) has not been implemented")
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}
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}
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fileprivate class MessageViewController: UIViewController {
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var message: String {
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didSet {
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preferredContentSize.width = CGFloat(message.count * 10)
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}
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}
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init(message: String) {
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self.message = message
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super.init(nibName: nil, bundle: nil)
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preferredContentSize.width = CGFloat(message.count * 10)
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}
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@available(*, unavailable) required init?(coder: NSCoder) {
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fatalError("init(coder:) has not been implemented")
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}
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}
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class DescribedViewControllerTests: XCTestCase {
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func test_init() {
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// Given
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let screen = TestScreen.counter(0)
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// When
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let describedViewController = DescribedViewController(screen: screen, environment: .empty)
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// Then
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guard
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let currentViewController = describedViewController.currentViewController as? CounterViewController
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else {
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XCTFail("Expected a \(String(reflecting: CounterViewController.self)), but got: \(describedViewController.currentViewController)")
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return
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}
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XCTAssertEqual(currentViewController.count, 0)
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XCTAssertFalse(describedViewController.isViewLoaded)
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XCTAssertFalse(currentViewController.isViewLoaded)
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XCTAssertNil(currentViewController.parent)
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}
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func test_viewDidLoad() {
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// Given
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let screen = TestScreen.counter(0)
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let describedViewController = DescribedViewController(screen: screen, environment: .empty)
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// When
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_ = describedViewController.view
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// Then
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XCTAssertEqual(describedViewController.currentViewController.parent, describedViewController)
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XCTAssertNotNil(describedViewController.currentViewController.viewIfLoaded?.superview)
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}
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func test_update_toCompatibleDescription_beforeViewLoads() {
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// Given
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let screenA = TestScreen.counter(0)
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let screenB = TestScreen.counter(1)
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let describedViewController = DescribedViewController(screen: screenA, environment: .empty)
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let initialChildViewController = describedViewController.currentViewController
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// When
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describedViewController.update(screen: screenB, environment: .empty)
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// Then
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XCTAssertEqual(initialChildViewController, describedViewController.currentViewController)
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XCTAssertEqual((describedViewController.currentViewController as? CounterViewController)?.count, 1)
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XCTAssertFalse(describedViewController.isViewLoaded)
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XCTAssertFalse(describedViewController.currentViewController.isViewLoaded)
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XCTAssertNil(describedViewController.currentViewController.parent)
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}
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func test_update_toCompatibleDescription_afterViewLoads() {
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// Given
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let screenA = TestScreen.counter(0)
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let screenB = TestScreen.counter(1)
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let describedViewController = DescribedViewController(screen: screenA, environment: .empty)
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let initialChildViewController = describedViewController.currentViewController
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// When
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_ = describedViewController.view
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describedViewController.update(screen: screenB, environment: .empty)
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// Then
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XCTAssertEqual(initialChildViewController, describedViewController.currentViewController)
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XCTAssertEqual((describedViewController.currentViewController as? CounterViewController)?.count, 1)
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}
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func test_update_toIncompatibleDescription_beforeViewLoads() {
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// Given
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let screenA = TestScreen.counter(0)
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let screenB = TestScreen.message("Test")
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let describedViewController = DescribedViewController(screen: screenA, environment: .empty)
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let initialChildViewController = describedViewController.currentViewController
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// When
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describedViewController.update(screen: screenB, environment: .empty)
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// Then
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XCTAssertNotEqual(initialChildViewController, describedViewController.currentViewController)
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XCTAssertEqual((describedViewController.currentViewController as? MessageViewController)?.message, "Test")
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XCTAssertFalse(describedViewController.isViewLoaded)
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XCTAssertFalse(describedViewController.currentViewController.isViewLoaded)
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XCTAssertNil(describedViewController.currentViewController.parent)
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}
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func test_update_toIncompatibleDescription_afterViewLoads() {
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// Given
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let screenA = TestScreen.counter(0)
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let screenB = TestScreen.message("Test")
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let describedViewController = DescribedViewController(screen: screenA, environment: .empty)
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let initialChildViewController = describedViewController.currentViewController
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// When
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_ = describedViewController.view
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describedViewController.update(screen: screenB, environment: .empty)
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// Then
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XCTAssertNotEqual(initialChildViewController, describedViewController.currentViewController)
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XCTAssertEqual((describedViewController.currentViewController as? MessageViewController)?.message, "Test")
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XCTAssertNil(initialChildViewController.parent)
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XCTAssertEqual(describedViewController.currentViewController.parent, describedViewController)
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XCTAssertNil(initialChildViewController.viewIfLoaded?.superview)
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XCTAssertNotNil(describedViewController.currentViewController.viewIfLoaded?.superview)
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}
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func test_childViewControllerFor() {
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// Given
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let screen = TestScreen.counter(0)
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let describedViewController = DescribedViewController(screen: screen, environment: .empty)
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let currentViewController = describedViewController.currentViewController
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// When, Then
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XCTAssertEqual(describedViewController.childForStatusBarStyle, currentViewController)
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XCTAssertEqual(describedViewController.childForStatusBarHidden, currentViewController)
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XCTAssertEqual(describedViewController.childForHomeIndicatorAutoHidden, currentViewController)
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XCTAssertEqual(describedViewController.childForScreenEdgesDeferringSystemGestures, currentViewController)
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XCTAssertEqual(describedViewController.supportedInterfaceOrientations, currentViewController.supportedInterfaceOrientations)
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}
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func test_childViewControllerFor_afterIncompatibleUpdate() {
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// Given
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let screenA = TestScreen.counter(0)
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let screenB = TestScreen.message("Test")
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let describedViewController = DescribedViewController(screen: screenA, environment: .empty)
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let initialChildViewController = describedViewController.currentViewController
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describedViewController.update(screen: screenB, environment: .empty)
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let currentViewController = describedViewController.currentViewController
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// When, Then
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XCTAssertNotEqual(initialChildViewController, currentViewController)
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XCTAssertEqual(describedViewController.childForStatusBarStyle, currentViewController)
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XCTAssertEqual(describedViewController.childForStatusBarHidden, currentViewController)
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XCTAssertEqual(describedViewController.childForHomeIndicatorAutoHidden, currentViewController)
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XCTAssertEqual(describedViewController.childForScreenEdgesDeferringSystemGestures, currentViewController)
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XCTAssertEqual(describedViewController.supportedInterfaceOrientations, currentViewController.supportedInterfaceOrientations)
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}
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func test_preferredContentSizeDidChange() {
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// Given
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let screenA = TestScreen.counter(1)
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let screenB = TestScreen.counter(2)
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let describedViewController = DescribedViewController(screen: screenA, environment: .empty)
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let containerViewController = ContainerViewController(describedViewController: describedViewController)
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// When
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let expectation = self.expectation(description: "did observe size changes")
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expectation.expectedFulfillmentCount = 2
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var observedSizes: [CGSize] = []
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let disposable = containerViewController.preferredContentSizeSignal.observeValues {
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observedSizes.append($0)
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expectation.fulfill()
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}
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defer { disposable?.dispose() }
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_ = containerViewController.view
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describedViewController.update(screen: screenB, environment: .empty)
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// Then
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let expectedSizes = [CGSize(width: 10, height: 0), CGSize(width: 20, height: 0)]
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waitForExpectations(timeout: 1, handler: nil)
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XCTAssertEqual(observedSizes, expectedSizes)
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}
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func test_preferredContentSizeDidChange_afterIncompatibleUpdate() {
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// Given
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let screenA = TestScreen.counter(1)
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let screenB = TestScreen.message("Test")
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let screenC = TestScreen.message("Testing")
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let describedViewController = DescribedViewController(screen: screenA, environment: .empty)
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let containerViewController = ContainerViewController(describedViewController: describedViewController)
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// When
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let expectation = self.expectation(description: "did observe size changes")
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expectation.expectedFulfillmentCount = 3
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var observedSizes: [CGSize] = []
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let disposable = containerViewController.preferredContentSizeSignal.observeValues {
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observedSizes.append($0)
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expectation.fulfill()
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}
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defer { disposable?.dispose() }
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_ = containerViewController.view
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describedViewController.update(screen: screenB, environment: .empty)
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describedViewController.update(screen: screenC, environment: .empty)
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// Then
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let expectedSizes = [
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CGSize(width: 10, height: 0),
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CGSize(width: 40, height: 0),
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CGSize(width: 70, height: 0),
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]
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waitForExpectations(timeout: 1, handler: nil)
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XCTAssertEqual(observedSizes, expectedSizes)
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}
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}
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#endif

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