title: Setting the turnState for DialogTestClient
body: <p>I am using the BotBuilderSDK v4. I am trying to use the DialogTestClient to unit my code. In the Dialog, my code is doing the following <code>BotMessage message = (BotMessage)stepContext.Context.TurnState[&quot;botMessage&quot;];</code></p>
  <p>How can I set this object botMessage into the turnState with the DialogTestClient in order to unit test this Dialog. Right now I am seeing this error :</p>
  <p><code>System.Collections.Generic.KeyNotFoundException : The given key 'botMessage' was not present in the dictionary.</code></p>