[dotnet-watch] Use Spectre.Console for target framework selection

Replace the basic numeric-key console prompt with Spectre.Console's
SelectionPrompt for target framework selection in dotnet-watch. This
matches the dotnet-run behavior and provides arrow key navigation,
search, and pagination.

- Add Spectre.Console dependency to Watch library
- Add Spectre.Console.Testing for unit tests
- Accept IAnsiConsole in TargetFrameworkSelectionPrompt for testability
- Use ShowAsync with CancellationToken for cancellation support
- Localize prompt strings in Resources.resx
- Rewrite tests to drive the prompt via TestConsole key presses

Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>

Author: jonathanpeppers

Directory.Packages.props

@@ -117,6 +117,7 @@
     <PackageVersion Include="runtime.linux-x64.Microsoft.NETCore.DotNetHostResolver" Version="$(MicrosoftNETCoreDotNetHostResolverPackageVersion)" />
     <PackageVersion Include="runtime.osx-x64.Microsoft.NETCore.DotNetHostResolver" Version="$(MicrosoftNETCoreDotNetHostResolverPackageVersion)" />
     <PackageVersion Include="Spectre.Console" Version="0.54.0" />
+    <PackageVersion Include="Spectre.Console.Testing" Version="0.54.0" />
     <PackageVersion Include="StyleCop.Analyzers" Version="$(StyleCopAnalyzersPackageVersion)" />
     <PackageVersion Include="System.CodeDom" Version="$(SystemCodeDomPackageVersion)" />
     <PackageVersion Include="System.CommandLine" Version="$(SystemCommandLineVersion)" />

src/Dotnet.Watch/Watch/HotReload/HotReloadDotNetWatcher.cs

@@ -25,7 +25,7 @@ internal sealed class HotReloadDotNetWatcher
 
     internal Task? Test_FileChangesCompletedTask { get; set; }
 
-    public HotReloadDotNetWatcher(DotNetWatchContext context, IConsole console, IRuntimeProcessLauncherFactory? runtimeProcessLauncherFactory)
+    public HotReloadDotNetWatcher(DotNetWatchContext context, IConsole console, IRuntimeProcessLauncherFactory? runtimeProcessLauncherFactory, TargetFrameworkSelectionPrompt? targetFrameworkSelectionPrompt = null)
     {
         _context = context;
         _console = console;
@@ -41,7 +41,7 @@ public HotReloadDotNetWatcher(DotNetWatchContext context, IConsole console, IRun
             }
 
             _rudeEditRestartPrompt = new RestartPrompt(context.Logger, consoleInput, noPrompt ? true : null);
-            _targetFrameworkSelectionPrompt = new TargetFrameworkSelectionPrompt(consoleInput);
+            _targetFrameworkSelectionPrompt = targetFrameworkSelectionPrompt;
         }
 
         _designTimeBuildGraphFactory = new ProjectGraphFactory(

src/Dotnet.Watch/Watch/Microsoft.DotNet.HotReload.Watch.csproj

@@ -32,6 +32,7 @@
     <PackageReference Include="Microsoft.CodeAnalysis.CSharp.Features" />
     <PackageReference Include="Microsoft.CodeAnalysis.ExternalAccess.HotReload" />
     <PackageReference Include="Microsoft.DotNet.ProjectTools" Condition="'$(ProjectToolsProjectDir)' == ''" />
+    <PackageReference Include="Spectre.Console" />
   </ItemGroup>
 
   <ItemGroup>

src/Dotnet.Watch/Watch/UI/TargetFrameworkSelectionPrompt.cs

@@ -1,16 +1,18 @@
-// Licensed to the .NET Foundation under one or more agreements.
+// Licensed to the .NET Foundation under one or more agreements.
 // The .NET Foundation licenses this file to you under the MIT license.
 
+using Spectre.Console;
+
 namespace Microsoft.DotNet.Watch;
 
-internal sealed class TargetFrameworkSelectionPrompt(ConsoleInputReader inputReader)
+internal sealed class TargetFrameworkSelectionPrompt(string title, string moreChoicesText, string searchPlaceholderText, IAnsiConsole? console = null)
 {
     public IReadOnlyList<string>? PreviousTargetFrameworks { get; set; }
     public string? PreviousSelection { get; set; }
 
     public async ValueTask<string> SelectAsync(IReadOnlyList<string> targetFrameworks, CancellationToken cancellationToken)
     {
-        var orderedTargetFrameworks = targetFrameworks.Order().ToArray();
+        var orderedTargetFrameworks = targetFrameworks.Order(StringComparer.OrdinalIgnoreCase).ToArray();
 
         if (PreviousSelection != null && PreviousTargetFrameworks?.SequenceEqual(orderedTargetFrameworks, StringComparer.OrdinalIgnoreCase) == true)
         {
@@ -19,21 +21,15 @@ public async ValueTask<string> SelectAsync(IReadOnlyList<string> targetFramework
 
         PreviousTargetFrameworks = orderedTargetFrameworks;
 
-        var keyInfo = await inputReader.GetKeyAsync(
-            $"Select target framework:{Environment.NewLine}{string.Join(Environment.NewLine, targetFrameworks.Select((tfm, i) => $"{i + 1}) {tfm}"))}",
-            AcceptKey,
-            cancellationToken);
-
-        _ = TryGetIndex(keyInfo, out var index);
-        return PreviousSelection = targetFrameworks[index];
-
-        bool TryGetIndex(ConsoleKeyInfo info, out int index)
-        {
-            index = info.KeyChar - '1';
-            return index >= 0 && index < targetFrameworks.Count;
-        }
+        var prompt = new SelectionPrompt<string>()
+            .Title($"[cyan]{Markup.Escape(title)}[/]")
+            .PageSize(10)
+            .MoreChoicesText($"[gray]({Markup.Escape(moreChoicesText)})[/]")
+            .AddChoices(targetFrameworks)
+            .EnableSearch()
+            .SearchPlaceholderText(searchPlaceholderText);
 
-        bool AcceptKey(ConsoleKeyInfo info)
-            => info is { Modifiers: ConsoleModifiers.None } && TryGetIndex(info, out _);
+        PreviousSelection = await prompt.ShowAsync(console ?? AnsiConsole.Console, cancellationToken);
+        return PreviousSelection;
     }
 }

src/Dotnet.Watch/dotnet-watch/Program.cs

@@ -265,7 +265,9 @@ internal async Task<int> RunAsync()
 
             if (IsHotReloadEnabled())
             {
-                var watcher = new HotReloadDotNetWatcher(context, console, runtimeProcessLauncherFactory: null);
+                var tfmPrompt = context.Options.NonInteractive ? null
+                    : new TargetFrameworkSelectionPrompt(Resources.SelectTargetFrameworkPrompt, Resources.MoreFrameworksText, Resources.SearchPlaceholderText);
+                var watcher = new HotReloadDotNetWatcher(context, console, runtimeProcessLauncherFactory: null, tfmPrompt);
                 await watcher.WatchAsync(shutdownHandler.CancellationToken);
             }
             else if (mainProjectOptions.Representation.EntryPointFilePath != null)

src/Dotnet.Watch/dotnet-watch/Resources.resx

@@ -138,6 +138,15 @@
     <value>Warning NETSDK1174: The abbreviation of -p for --project is deprecated. Please use --project.</value>
     <comment>{Locked="-p"}{Locked="--project"}</comment>
   </data>
+  <data name="SelectTargetFrameworkPrompt" xml:space="preserve">
+    <value>Select the target framework to run:</value>
+  </data>
+  <data name="MoreFrameworksText" xml:space="preserve">
+    <value>Move up and down to reveal more frameworks</value>
+  </data>
+  <data name="SearchPlaceholderText" xml:space="preserve">
+    <value>Type to search</value>
+  </data>
   <data name="Help_NonInteractive" xml:space="preserve">
     <value>
       Runs dotnet-watch in non-interactive mode. This option is only supported when running with Hot Reload enabled.