单元测试 StreamingOutput 作为响应实体 Jersey

Question

我正在做类似于中提到的事情 Example of using StreamingOutput as Response entity in Jersey

@GET
@Produces(MediaType.APPLICATION_OCTET_STREAM)
public Response streamExample(@Context UriInfo uriInfo) {
  StreamingOutput stream = new StreamingOutput() {
    @Override
    public void write(OutputStream os) throws IOException,WebApplicationException {
    try{
      Writer writer = new BufferedWriter(new OutputStreamWriter(os));
      //Read resource from jar
      InputStream inputStream = getClass().getClassLoader().getResourceAsStream("public/" + uriInfo.getPath());

      ...//manipulate the inputstream and build string with StringBuilder here//.......
      String inputData = builder.toString();
      Writer writer = new BufferedWriter(new OutputStreamWriter(os));
      writer.write(inputData);
      writer.flush();
    } catch (ExceptionE1) {
        throw new WebApplicationException();
      }
    }
};
  return Response.ok(stream,MediaType.APPLICATION_OCTET_STREAM).build();
}

我正在尝试通过像How to get instance of javax.ws.rs.core.UriInfo 中提到的那样模拟 URIInfo 来对此进行单元测试

  public void testStreamExample() throws IOException, URISyntaxException {
        UriInfo mockUriInfo = mock(UriInfo.class);
        Mockito.when(mockUriInfo.getPath()).thenReturn("unusal-path");
        Response response = myresource.streamExample(mockUriInfo);}

当我将 jar 的路径切换到其他东西时，我希望能够检查我是否得到了一个异常。但是，当我运行/调试测试时，我从不进入

public void write(OutputStream os) throws IOException,
            WebApplicationException {...}

部分，我只打return Response.ok(stream,MediaType.APPLICATION_OCTET_STREAM).build();

我在这里遗漏了一些非常明显的东西吗？

Answer 1

因为流在到达MessageBodyWriter（这是最终调用StreamingOutput#write 的组件）之前不会被写入。

您可以做的就是从返回中获取Response 并调用Response#getEntity()（它返回一个对象）并将其转换为StreamingOutput。然后自己调用write方法，传递一个OutputStream，也许是一个ByteArrayOutputStream，这样你就可以得到一个byte[]的内容来检查它。这一切看起来都像

UriInfo mockInfo = mockUriInfo();
Response response = resource.streamExample(mockInfo);
StreamingOutput output = (StreamingOutput) response.getEntity();
ByteArrayOutputStream baos = new ByteArrayOutputStream();
output.write(baos);
byte[] data = baos.toByteArray();
String s = new String(data, StandardCharsets.UTF_8);
assertThat(s, is("SomeCharacterData"));