node-postgres/packages/pg-query-stream/test/slow-reader.js

var helper = require('./helper');
var QueryStream = require('../');
var concat = require('concat-stream');

var Transform = require('stream').Transform;

var mapper = new Transform({ objectMode: true });

mapper._transform = function (obj, enc, cb) {
  this.push(obj);
  setTimeout(cb, 5);
};

helper('slow reader', function (client) {
  it('works', function (done) {
    this.timeout(50000);
    var stream = new QueryStream('SELECT * FROM generate_series(0, 201) num', [], {
      highWaterMark: 100,
      batchSize: 50,
    });
    stream.on('end', function () {
      // console.log('stream end')
    });
    client.query(stream);
    stream.pipe(mapper).pipe(
      concat(function (res) {
        done();
      })
    );
  });
});