title: SignalR client not receiving messages in integration tests
body: <p>I am trying to test my SignalR connections in my integration tests.<br />
  The client looks like this:</p>
  <pre class="lang-cs prettyprint-override"><code>var connection = new HubConnectionBuilder()
                       .WithUrl(
                          $&quot;{client.BaseAddress}meeting-notifications&quot;,
                           o =&gt;
                           {
                               o.HttpMessageHandlerFactory = _ =&gt; Server?.CreateHandler();
                           })
                       .Build();
  
  connection.On&lt;BoardDto&gt;(&quot;BoardStateChanged&quot;, board =&gt; { Do Something... });
  
  await connection.StartAsync();
  </code></pre>
  <p>I am calling the method in my ASP-NET Core backend like so:</p>
  <pre class="lang-cs prettyprint-override"><code>public async Task BroadcastBoardStateAsync(int boardId, BoardDto board)
  {
      await _notificationHub.Clients.All.BoardStateChanged(board);
  }
  </code></pre>
  <p>The client is able to call a method on the server but not the other way around.<br />
  Does anyone know what I am missing here?</p>
  <p>Edit: I debugged the server call and the <code>_notificationHub</code> contains the connection-id of the client.</p>