使用Express发送故意无效的HTTP响应

Question

I'm building a few tests for a web app and I'd like to test the ability of the client to gracefully handle invalid HTTP responses. How do you suggest mangling a response such that it's not longer valid? I tried the following but Express evidently fixed the Content-Length afterwards:

app.get('/broken/', function(req, res) {
    console.log('request received for ' + req.path);
    res.set('Content-Length', 0).send('more than zero');
});

EDIT: To note, I'm not necessarily in control of the incoming requests. In the past some of them have been invalid.

Answer 1

Indeed, Express resets Content-Length inside response.send method.

if (chunk !== undefined) {
  len = chunk.length;
  this.set('Content-Length', len);
}

Basically, send does nothing more than setting a bunch of headers and delegating the rest of work to http.ServerResponse.end .

In order to bypass this behaviour, you could use end method directly.

app.get('/broken/', function(req, res) {
  res.set('Content-Length', 0)
     .set('Content-Type', type);
     .end('more than zero');
});

Answer 2

I think the right answer (even if you can work around it) is to not use a HTTP client for this. Any HTTP client would make an effort to prevent you from making invalid HTTP calls. The correct answer therefore is to make an intentionally non-conforming HTTP client, which implies you need to dive down to writing tcp sockets. Even if this means that this doesn't fully fit in your testing framework, I presume that you only need this for one test.