function handler(err, container) {
        expect(err).to.be.null;
        expect(container).to.be.ok;

        var attach_opts = {
          stream: true,
          stdin: true,
          stdout: true,
          stderr: true,
          hijack: true
        };
        container.attach(attach_opts, function handler(err, stream) {
          expect(err).to.be.null;
          expect(stream).to.be.ok;

          var memStream = new MemoryStream();
          var output = '';
          memStream.on('data', function(data) {
            output += data.toString();
          });

          stream.pipe(memStream);

          container.start(function(err, data) {
            expect(err).to.be.null;

            var aux = randomString(size) + '\n\x04';
            stream.write(aux);

            container.wait(function(err, data) {
              expect(err).to.be.null;
              expect(data).to.be.ok;
              expect(+output.slice(size)).to.equal(size + 1);
              done();
            });
          });
        });
      }
simple test that writes 1000 bytes to the "wc -c" command, that command
returns the number of bytes it received, so it should return 1000 for this test