Durable Orchestrator not calling Activity in Integration Test

Question

I have application that uses Azure Durable Orchestrators and Activties and I am trying to write Integration Test for it by following the instructions here.. Mind you this Function App runs successfully in the Azure Runtime, so I am trying to isolate why it is throwing this misleading error using this approach

I am using a custom configuration that utilizes the HodtBuilder setup below

 public FunctioningInitializer(int portNumber)
 {
     configuration = new ConfigurationBuilder()
     .SetBasePath(Directory.GetCurrentDirectory())
     .AddJsonFile("appsettings.functioning.json")
     .Build();

     var host = new HostBuilder()
     .ConfigureWebJobs((context, builder) =>
     {
         new FunctioningStartup(portNumber).Configure(new WebJobsBuilderContext()
         {
             ApplicationRootPath = context.HostingEnvironment.ContentRootPath,
             Configuration = configuration,
             EnvironmentName = context.HostingEnvironment.EnvironmentName
         }, builder);

         // Add Durable Task services
         builder.AddDurableTask(options =>
         {
             options.HubName = "AppHub";                    
         });

         builder.AddAzureStorageCoreServices();
     })
     .ConfigureAppConfiguration((context, builder) =>
     {
         // Existing configuration settings
     })
     .Build();

     

     try
     {
         host.Run();
         //host.StartAsync().GetAwaiter().GetResult();
     }
     catch (FunctionIndexingException ex)
     {
         Console.WriteLine(ex.Message);
     }

     ServiceProvider = host.Services;
 }

 public IServiceProvider ServiceProvider { get; }

But when I run this I get the below exception

OneTimeSetUp: Microsoft.Azure.WebJobs.Host.Indexers.FunctionIndexingException : Error indexing method 'FunctioningTrigger' ----> System.InvalidOperationException : Functions must return Task or void, have a binding attribute for the return value, or be triggered by a binding that natively supports return values.

The function is referencing in this exception is defined as below

public async Task<IActionResult> FunctioningTrigger(
    [HttpTrigger(AuthorizationLevel.Anonymous, "put", "patch", Route = "v3/functioning")] HttpRequest request,
    [DurableClient] IDurableOrchestrationClient durableClient,
    ILogger logger)

So I am wondering why I am getting this wrong signature exception, any help or hint would be appreciated.

Update

Seems the WebJobs SDK does not know how to use the [DurableClient] IDurableOrchestrationClient durableClient binding during Function Indexing, removing that binding makes the Test Host start successfully.