chore: import upstream snapshot with attribution

dotnet/samples/GettingStarted/Step4_Dependency_Injection.cs

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+// Copyright (c) Microsoft. All rights reserved.
+
+using System.ComponentModel;
+using Microsoft.Extensions.DependencyInjection;
+using Microsoft.Extensions.Logging;
+using Microsoft.SemanticKernel;
+
+namespace GettingStarted;
+
+/// <summary>
+/// This example shows how to using Dependency Injection with the Semantic Kernel
+/// </summary>
+public sealed class Step4_Dependency_Injection(ITestOutputHelper output) : BaseTest(output)
+{
+    /// <summary>
+    /// Show how to create a <see cref="Kernel"/> that participates in Dependency Injection.
+    /// </summary>
+    [Fact]
+    public async Task GetKernelUsingDependencyInjection()
+    {
+        // If an application follows DI guidelines, the following line is unnecessary because DI will inject an instance of the KernelClient class to a class that references it.
+        // DI container guidelines - https://learn.microsoft.com/en-us/dotnet/core/extensions/dependency-injection-guidelines#recommendations
+        var serviceProvider = BuildServiceProvider();
+        var kernel = serviceProvider.GetRequiredService<Kernel>();
+
+        // Invoke the kernel with a templated prompt and stream the results to the display
+        KernelArguments arguments = new() { { "topic", "earth when viewed from space" } };
+        await foreach (var update in
+                       kernel.InvokePromptStreamingAsync("What color is the {{$topic}}? Provide a detailed explanation.", arguments))
+        {
+            Console.Write(update);
+        }
+    }
+
+    /// <summary>
+    /// Show how to use a plugin that participates in Dependency Injection.
+    /// </summary>
+    [Fact]
+    public async Task PluginUsingDependencyInjection()
+    {
+        // If an application follows DI guidelines, the following line is unnecessary because DI will inject an instance of the Kernel class to a class that references it.
+        // DI container guidelines - https://learn.microsoft.com/en-us/dotnet/core/extensions/dependency-injection-guidelines#recommendations
+        var serviceProvider = BuildServiceProvider();
+        var kernel = serviceProvider.GetRequiredService<Kernel>();
+
+        // Invoke the prompt which relies on invoking a plugin that depends on a service made available using Dependency Injection.
+        PromptExecutionSettings settings = new() { FunctionChoiceBehavior = FunctionChoiceBehavior.Auto() };
+        Console.WriteLine(await kernel.InvokePromptAsync("Greet the current user by name.", new(settings)));
+    }
+
+    /// <summary>
+    /// Build a ServiceProvider that can be used to resolve services.
+    /// </summary>
+    private ServiceProvider BuildServiceProvider()
+    {
+        var collection = new ServiceCollection();
+        collection.AddSingleton<ILoggerFactory>(new XunitLogger(this.Output));
+        collection.AddSingleton<IUserService>(new FakeUserService());
+
+        // Add ChatClient using OpenAI
+        collection.AddOpenAIChatClient(
+            modelId: TestConfiguration.OpenAI.ChatModelId,
+            apiKey: TestConfiguration.OpenAI.ApiKey);
+
+        var kernelBuilder = collection.AddKernel();
+        kernelBuilder.Plugins.AddFromType<TimeInformation>();
+        kernelBuilder.Plugins.AddFromType<UserInformation>();
+
+        return collection.BuildServiceProvider();
+    }
+
+    /// <summary>
+    /// A plugin that returns the current time.
+    /// </summary>
+    public class TimeInformation(ILoggerFactory loggerFactory)
+    {
+        private readonly ILogger _logger = loggerFactory.CreateLogger<TimeInformation>();
+
+        [KernelFunction]
+        [Description("Retrieves the current time in UTC.")]
+        public string GetCurrentUtcTime()
+        {
+            var utcNow = DateTime.UtcNow.ToString("R");
+            this._logger.LogInformation("Returning current time {0}", utcNow);
+            return utcNow;
+        }
+    }
+
+    /// <summary>
+    /// A plugin that returns the current time.
+    /// </summary>
+    public class UserInformation(IUserService userService)
+    {
+        [KernelFunction]
+        [Description("Retrieves the current users name.")]
+        public string GetUsername()
+        {
+            return userService.GetCurrentUsername();
+        }
+    }
+
+    /// <summary>
+    /// Interface for a service to get the current user id.
+    /// </summary>
+    public interface IUserService
+    {
+        /// <summary>
+        /// Return the user id for the current user.
+        /// </summary>
+        string GetCurrentUsername();
+    }
+
+    /// <summary>
+    /// Fake implementation of <see cref="IUserService"/>
+    /// </summary>
+    public class FakeUserService : IUserService
+    {
+        /// <inheritdoc/>
+        public string GetCurrentUsername() => "Bob";
+    }
+}