Play Framework&Scala：单元测试中FakeRequest和JSON POST的

问题：获得400个错误请求,无效Json作为响应,具有以下异常：

com.fasterxml.jackson.databind.JsonMappingException: No content to map due to end-of-input
 at [Source: [B@6ee503c9; line: 1,column: 1]
    at com.fasterxml.jackson.databind.JsonMappingException.from(JsonMappingException.java:164) ~[jackson-databind.jar:2.2.2]
    at com.fasterxml.jackson.databind.ObjectMapper._initForReading(ObjectMapper.java:2931) ~[jackson-databind.jar:2.2.2]
    at com.fasterxml.jackson.databind.ObjectMapper._readValue(ObjectMapper.java:2846) ~[jackson-databind.jar:2.2.2]
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:1569) ~[jackson-databind.jar:2.2.2]
    at play.api.libs.json.JacksonJson$.parseJsValue(JsValue.scala:480) ~[play-json_2.10.jar:2.2.0]
    at play.api.libs.json.Json$.parse(Json.scala:27) ~[play-json_2.10.jar:2.2.0]

在我的控制器中测试的方法：

def createArticle(id: String) =
      Action.async(parse.json) { implicit request =>
        (request.body  "content").asOpt[String].map {
            ............
            ............
        }.getOrElse(BadRequest("Invalid request body"))
      }

相应的单元测试：

"create article" in {
    running(FakeApplication()) {
      val postJson = Json.obj("content" -> "article content")

      val result = resource.createArticle(ARTICE_ID)(FakeRequest(POST,controllers.routes.ArticleResource.create(ARTICLE_ID).url).withJsonBody(postJson).withHeaders(CONTENT_TYPE -> "application/json").run

      status(result) must equalTo OK
    }
  }

我读了here的讨论,但没有任何建议有帮助.