chore: import upstream snapshot with attribution

dotnet/samples/Concepts/Functions/MethodFunctions_Yaml.cs

@@ -0,0 +1,73 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System.Reflection;
+using Microsoft.SemanticKernel;
+
+namespace Functions;
+
+public class MethodFunctions_Yaml(ITestOutputHelper output) : BaseTest(output)
+{
+    private const string FunctionConfig = """
+        name: ValidateTaskId
+        description: Validate a task id.
+        input_variables:
+          - name: kernel
+            description: Kernel instance.
+          - name: taskId
+            description: Task identifier.
+            is_required: true
+        output_variable:
+          description: String indicating whether or not the task id is valid.
+        """;
+
+    /// <summary>
+    /// This example create a plugin and uses a separate configuration file for the function metadata.
+    /// </summary>
+    /// <remarks>
+    /// Some reasons you would want to do this:
+    /// 1. It's not possible to modify the existing code to add the KernelFunction attribute.
+    /// 2. You want to keep the function metadata separate from the function implementation.
+    /// </remarks>
+    [Fact]
+    public async Task CreateFunctionFromMethodWithYamlConfigAsync()
+    {
+        var kernel = new Kernel();
+
+        var config = KernelFunctionYaml.ToPromptTemplateConfig(FunctionConfig);
+
+        var target = new ValidatorPlugin();
+        MethodInfo method = target.GetType().GetMethod(config.Name!)!;
+        var functions = new List<KernelFunction>();
+        var functionName = config.Name;
+        var description = config.Description;
+        var parameters = config.InputVariables;
+        functions.Add(KernelFunctionFactory.CreateFromMethod(method, target, new()
+        {
+            FunctionName = functionName,
+            Description = description,
+            Parameters = parameters.Select(p => new KernelParameterMetadata(p.Name) { Description = p.Description, IsRequired = p.IsRequired }).ToList(),
+        }));
+
+        var plugin = kernel.ImportPluginFromFunctions("ValidatorPlugin", functions);
+
+        var function = plugin["ValidateTaskId"];
+        var result = await kernel.InvokeAsync(function, new() { { "taskId", "1234" } });
+        Console.WriteLine(result.GetValue<string>());
+
+        Console.WriteLine("Function Metadata:");
+        Console.WriteLine(function.Metadata.Description);
+        Console.WriteLine(function.Metadata.Parameters[0].Description);
+        Console.WriteLine(function.Metadata.Parameters[1].Description);
+    }
+
+    /// <summary>
+    /// Plugin example with no KernelFunction or Description attributes.
+    /// </summary>
+    private sealed class ValidatorPlugin
+    {
+        public string ValidateTaskId(Kernel kernel, string taskId)
+        {
+            return taskId.Equals("1234", StringComparison.Ordinal) ? "Valid task id" : "Invalid task id";
+        }
+    }
+}