.Net: Add support for custom authentication provider for OpenAPI

dotnet/src/Skills/Skills.OpenAPI/Authentication/CustomAuthenticationProvider.cs

@@ -0,0 +1,39 @@
+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Net.Http;
+using System.Threading.Tasks;
+
+namespace Microsoft.SemanticKernel.Skills.OpenAPI.Authentication;
+
+/// <summary>
+/// Retrieves authentication content (scheme and value) via the provided delegate and applies it to HTTP requests.
+/// </summary>
+public sealed class CustomAuthenticationProvider
+{
+    private readonly Func<Task<string>> _header;
+    private readonly Func<Task<string>> _value;
+
+    /// <summary>
+    /// Creates an instance of the <see cref="CustomAuthenticationProvider"/> class.
+    /// </summary>
+    /// <param name="header">Delegate for retrieving the header name.</param>
+    /// <param name="value">Delegate for retrieving the value.</param>
+    public CustomAuthenticationProvider(Func<Task<string>> header, Func<Task<string>> value)
+    {
+        this._header = header;
+        this._value = value;
+    }
+
+    /// <summary>
+    /// Applies the header and value to the provided HTTP request message.
+    /// </summary>
+    /// <param name="request">The HTTP request message.</param>
+    /// <returns></returns>
+    public async Task AuthenticateRequestAsync(HttpRequestMessage request)
+    {
+        var header = await this._header().ConfigureAwait(false);
+        var value = await this._value().ConfigureAwait(false);
+        request.Headers.Add(header, value);
+    }
+}

dotnet/src/Skills/Skills.UnitTests/OpenAPI/Authentication/CustomAuthenticationProviderTests.cs

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+// Copyright (c) Microsoft. All rights reserved.
+
+using System;
+using System.Linq;
+using System.Net.Http;
+using System.Threading.Tasks;
+using Microsoft.SemanticKernel.Skills.OpenAPI.Authentication;
+using Xunit;
+
+namespace SemanticKernel.Skills.UnitTests.OpenAPI.Authentication;
+
+public class CustomAuthenticationProviderTests
+{
+    [Fact]
+    public async Task AuthenticateRequestAsyncSucceedsAsync()
+    {
+        // Arrange
+        var header = "X-MyHeader";
+        var value = Guid.NewGuid().ToString();
+
+        using var request = new HttpRequestMessage();
+
+        var target = new CustomAuthenticationProvider(() => Task.FromResult(header), () => Task.FromResult(value));
+
+        // Act
+        await target.AuthenticateRequestAsync(request);
+
+        // Assert
+        Assert.True(request.Headers.Contains(header));
+        Assert.Equal(request.Headers.GetValues(header).FirstOrDefault(), value);
+    }
+}