test: Verify DigestAuthenticator uses injected RestClientOptions

Added unit test VerifyHandshakeUsesInjectedClientOptions to ensure DigestAuthenticator correctly applies injected RestClientOptions (tested via Proxy callback) during the digest handshake request.

Author: simonabler

test/DigestAuthenticator.Tests/DigestIntegrationTest.cs

@@ -42,6 +42,8 @@ public async Task Given_ADigestAuthEndpoint_When_ITryToGetInfo_Then_TheAuthMustB
     [Fact]
     public async Task Given_ADigestAuthEndpoint_When_ITryToInjectOwnClient_Then_TheAuthMustBeResolved()
     {
+        bool proxyCalled = false;
+
         var loggerMock = Substitute.For<ILogger>();
         loggerMock.BeginScope("DigestServerStub");
 
@@ -50,13 +52,16 @@ public async Task Given_ADigestAuthEndpoint_When_ITryToInjectOwnClient_Then_TheA
 
         RestClientOptions options = new RestClientOptions()
         {
-            MaxRedirects = 2
+            Proxy = new TestProxy(() => proxyCalled = true)
         };
 
         var client = _fixture.CreateInjectedOptionClient(loggerMock, options);
         var response = await client.ExecuteAsync(request);
 
         response.StatusCode.Should().Be(HttpStatusCode.OK);
         loggerMock.ReceivedWithAnyArgs().LogDebug("NONONO");
+
+        Assert.True(proxyCalled, "Injected RestClientOptions.Proxy should be used in digest handshake.");
+
     }
 }

test/DigestAuthenticator.Tests/Fixtures/TestProxy.cs

@@ -0,0 +1,27 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using System.Net;
+using System.Text;
+using System.Threading.Tasks;
+
+namespace RestSharp.Authenticators.Digest.Tests.Fixtures;
+internal class TestProxy : IWebProxy
+{
+    private readonly Action _onProxyCalled;
+
+    public TestProxy(Action onProxyCalled)
+    {
+        _onProxyCalled = onProxyCalled;
+    }
+
+    public Uri GetProxy(Uri destination)
+    {
+        _onProxyCalled();
+        return destination;
+    }
+
+    public bool IsBypassed(Uri host) => false;
+
+    public ICredentials? Credentials { get; set; }
+}