[CmdPal][UnitTests] Add/Migrate unit test for WebSearch and Shell extension (#41272)

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## Summary of the Pull Request

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- [x] Closes: #41241 #41242
- [x] **Communication:** I've discussed this with core contributors
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- [x] **Tests:** Added/updated and all pass
- [ ] **Localization:** All end-user-facing strings can be localized
- [ ] **Dev docs:** Added/updated
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Co-authored-by: Yu Leng <yuleng@microsoft.com>

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.WebSearch/Commands/SearchWebCommand.cs

@@ -13,11 +13,11 @@ namespace Microsoft.CmdPal.Ext.WebSearch.Commands;
 
 internal sealed partial class SearchWebCommand : InvokableCommand
 {
-    private readonly SettingsManager _settingsManager;
+    private readonly ISettingsInterface _settingsManager;
 
     public string Arguments { get; internal set; } = string.Empty;
 
-    internal SearchWebCommand(string arguments, SettingsManager settingsManager)
+    internal SearchWebCommand(string arguments, ISettingsInterface settingsManager)
     {
         Arguments = arguments;
         BrowserInfo.UpdateIfTimePassed();

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.WebSearch/Helpers/ISettingsInterface.cs

@@ -0,0 +1,19 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Collections.Generic;
+using Microsoft.CommandPalette.Extensions.Toolkit;
+
+namespace Microsoft.CmdPal.Ext.WebSearch.Helpers;
+
+public interface ISettingsInterface
+{
+    public bool GlobalIfURI { get; }
+
+    public string ShowHistory { get; }
+
+    public List<ListItem> LoadHistory();
+
+    public void SaveHistory(HistoryItem historyItem);
+}

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.WebSearch/Helpers/SettingsManager.cs

@@ -14,7 +14,7 @@ using Microsoft.CommandPalette.Extensions.Toolkit;
 
 namespace Microsoft.CmdPal.Ext.WebSearch.Helpers;
 
-public class SettingsManager : JsonSettingsManager
+public class SettingsManager : JsonSettingsManager, ISettingsInterface
 {
     private readonly string _historyPath;
 

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.WebSearch/Pages/WebSearchListPage.cs

@@ -20,12 +20,12 @@ internal sealed partial class WebSearchListPage : DynamicListPage
 {
     private readonly string _iconPath = string.Empty;
     private readonly List<ListItem>? _historyItems;
-    private readonly SettingsManager _settingsManager;
+    private readonly ISettingsInterface _settingsManager;
     private static readonly CompositeFormat PluginInBrowserName = System.Text.CompositeFormat.Parse(Properties.Resources.plugin_in_browser_name);
     private static readonly CompositeFormat PluginOpen = System.Text.CompositeFormat.Parse(Properties.Resources.plugin_open);
     private List<ListItem> _allItems;
 
-    public WebSearchListPage(SettingsManager settingsManager)
+    public WebSearchListPage(ISettingsInterface settingsManager)
     {
         Name = Resources.command_item_title;
         Title = Resources.command_item_title;

src/modules/cmdpal/ext/Microsoft.CmdPal.Ext.WebSearch/Properties/AssemblyInfo.cs

@@ -0,0 +1,7 @@
+// Copyright (c) Microsoft Corporation
+// The Microsoft Corporation licenses this file to you under the MIT license.
+// See the LICENSE file in the project root for more information.
+
+using System.Runtime.CompilerServices;
+
+[assembly: InternalsVisibleTo("Microsoft.CmdPal.Ext.WebSearch.UnitTests")]