How to stop stream-to-promise changing my original buffer

Question

I'm using the stream-to-promise npm module to create the multipart/form-data payload in my jasmine test. My payload includes an image file as a buffer but when the payload is put through stream-to-promise it changes or corrupts my original image buffer in the payload somehow and so my tests are failing. Is there a way to prevent this?

  it('test /identity-verification/your-first-form-of-id POST with validation passing', function(done){
    var form = new FormData();
    var image = fs.createReadStream("image.png");
    streamToBuffer(image, function (err, buffer) {
      form.append('firstID', 'passport');
      form.append('firstIDImage', buffer);
      var headers = form.getHeaders();
      streamToPromise(form).then(function(payload) {
        var options = {
          method: 'POST',
          url: '/identity-verification/your-first-form-of-id',
          payload: payload,
          headers: headers
        };
        server.inject(options, function(response) {
          expect(response.statusCode).toBe(302);
          expect(response.headers.location).toMatch('/identity-verification/your-first-form-of-id/upload-successful');
          done();
        });
      });
    });
  });

The buffer in the payload after being put through stream-to-promise looks like this:

Are you logging buffer.toString()? That would explain the strange characters, maybe. What is the error message you receive when your tests fail? — Larry Turtis, Oct 20 '16 at 13:54
I'm logging request.payload in my handler function. My tests are failing because in my handler I am trying to read the file type from the buffer but it is coming out undefined as the buffer looks corrupt or something — Ruth, Oct 20 '16 at 14:07
It's an npm module so all I'm doing is: `var fileType = fileTypeModule(buffer);` but that comes out as null so when I then do `fileType.mime` it breaks. It works completely fine when I run the code through my browser so I know it has something to do with the test — Ruth, Oct 20 '16 at 14:29
Are you getting this error when you try the same with a JPG file? For some reason server.inject is only choking on PNG files for me. — Larry Turtis, Oct 20 '16 at 18:35

Larry Turtis · Accepted Answer · 2016-10-20T20:49:19.463

You don't need stream-to-buffer. You've already got the buffer from createReadStream. If you get rid of that, it should work. One thing to be careful of is that your maxBytes is set high enough to accomodate your test image. This was causing some cryptic errors when I was testing.

The code below is working fine for me.

 var streamToPromise = require("stream-to-promise");
 var FormData = require("form-data");
 var fileTypeModule = require("file-type");
 var fs = require("fs");
 var q = require("q");
 var Hapi = require('hapi');
 var server = new Hapi.Server({ debug: { request: ['error'] } });

 server.connection({
     host: 'localhost',
     port: 8000
 });

 server.route({
     method: 'POST',
     path: '/test',
     handler: function(request, reply) {
         var data = request.payload.firstIDImage;
         var fileType = fileTypeModule(data);
         reply(fileType);
     },
     config: {
         payload: { maxBytes: 1048576 }
     }
 });

 var start = server.start();
 var form = new FormData();
 var headers = form.getHeaders();

 form.append('firstID', 'passport');
 form.append('firstIDImage', fs.createReadStream("image.png"));
 var append = streamToPromise(form);
 q.all([start, append]).then((results) => {
     var options = {
         method: 'POST',
         url: '/test',
         payload: results[1],
         headers: headers
     };
     server.inject(options, function(response) {
        console.log(response.payload);
     });
 });

How to stop stream-to-promise changing my original buffer

1 Answers1