Get user access token for facebook test user using app access token.

gistfile1.txt

  val appId = "someId"
  val appAccessToken = "someAppAccessToken"
  
  def getTestUserAccessToken: Future[String] = {
    val accessTokenEncoded = URLEncoder.encode(appAccessToken, "US-ASCII")
    WS.url(s"https://graph.facebook.com/$appId/accounts/test-users?access_token=$accessTokenEncoded").get.map {
      response =>
        // for each returned user get the user id and access token
        (response.json \ "data").as[JsArray].value.map {
          case user: JsObject =>
            val JsString(userId) = user \ "id"
            val JsString(access_token) = user \ "access_token"

            (userId, access_token)
            
        // find the user
        } find {
          case (userId, _) =>  userId == testUserId
        
        // return the access token
        } map {
          case (_, access_token) => access_token
          
        // fail if it isn't found
        } getOrElse {
            fail("can't get user access token")

            "asdf"
        }
    }
  }