#2140 ✓resolved
David Costanzo

Chunked responses are not testable by FunctionalTest

Reported by David Costanzo | November 16th, 2017 @ 08:27 PM | in 1.5.1 (closed)

A controller action which writes its response in chunks is not testable by FunctionalTest.

I think the problem is that FunctionalTest does not register any onWriteChunk handlers on the Response object which it provides to the controller action, so when the controller action calls Response.writeChunk() it throws an UnsupportedOperationException in play.mvc.Http.Response.writeChunk(Object o)

public void writeChunk(Object o) {
    this.chunked = true;
    if (writeChunkHandlers.isEmpty()) { // <--- no onWriteChunk handlers have been registered
        throw new UnsupportedOperationException("Your HTTP server doesn't yet support chunked response stream");
    for (F.Action<Object> handler : writeChunkHandlers) {

I have reproduced this on play-1.4.4 (the version I'm using) and the latest code in GitHub.

Steps to Reproduce

1) Run play new to create a new application

2) Change Application.java to this

package controllers;

import play.mvc.Controller;

public class Application extends Controller {

    public static void index() {
        response.setContentTypeIfNotSet("text/html; charset=" + play.Play.defaultWebEncoding);
        response.writeChunk("Hello, World!");

3) Change ApplicationTest.java to

import org.junit.Test;

import play.mvc.Http.Response;
import play.test.FunctionalTest;

public class ApplicationTest extends FunctionalTest {

    public void testThatIndexPageWorks() {
        Response response = GET("/");
        assertContentType("text/html", response);
        assertCharset(play.Play.defaultWebEncoding, response);
        assertContentEquals("Hello, World!", response); // <-- this is added

4) Run play auto-test

What Happens:
ApplicationTest.testThatIndexPageWorks reports Failure, expected:<[Hello, World]> but was:<[]>.

Expected Result:
All tests pass.

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