App.xaml.cs

// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using System;

using Windows.ApplicationModel;
using Windows.ApplicationModel.Activation;
using Windows.UI.Xaml;
using Windows.UI.Xaml.Controls;
using Windows.UI.Xaml.Navigation;

namespace BlankUwpNet9App;

/// <summary>
/// Provides application-specific behavior to supplement the default Application class.
/// </summary>
public sealed partial class App : Application
{
    /// <summary>
    /// Initializes the singleton application object. This is the first line of authored code
    /// executed, and as such is the logical equivalent of main() or WinMain().
    /// </summary>
    public App()
    {
        InitializeComponent();

        Suspending += OnSuspending;
    }

    /// <inheritdoc/>
    protected override void OnLaunched(LaunchActivatedEventArgs args)
    {
        var rootFrame = Window.Current.Content as Frame;

        // Do not repeat app initialization when the Window already has content,
        // just ensure that the window is active.
        if (rootFrame == null)
        {
            // Create a Frame to act as the navigation context and navigate to the first page
            rootFrame = new Frame();

            rootFrame.NavigationFailed += OnNavigationFailed;

            if (args.PreviousExecutionState == ApplicationExecutionState.Terminated)
            {
                // TODO: Load state from previously suspended application
            }

            // Place the frame in the current Window
            Window.Current.Content = rootFrame;
        }

        Microsoft.VisualStudio.TestPlatform.TestExecutor.UnitTestClient.CreateDefaultUI();

        // Ensure the current window is active
        Window.Current.Activate();

        Microsoft.VisualStudio.TestPlatform.TestExecutor.UnitTestClient.Run(args.Arguments);
    }

    /// <summary>
    /// Invoked when Navigation to a certain page fails.
    /// </summary>
    /// <param name="sender">The Frame which failed navigation.</param>
    /// <param name="e">Details about the navigation failure.</param>
    private void OnNavigationFailed(object sender, NavigationFailedEventArgs e)
        => throw new Exception($"Failed to load page '{e.SourcePageType.FullName}'.");

    /// <summary>
    /// Invoked when application execution is being suspended. Application state is saved
    /// without knowing whether the application will be terminated or resumed with the contents
    /// of memory still intact.
    /// </summary>
    /// <param name="sender">The source of the suspend request.</param>
    /// <param name="e">Details about the suspend request.</param>
    private void OnSuspending(object sender, SuspendingEventArgs e)
    {
        SuspendingDeferral deferral = e.SuspendingOperation.GetDeferral();

        // TODO: Save application state and stop any background activity
        deferral.Complete();
    }
}