Run multiple Postman Collection in parallel — Stress-Tests

A known limitation of the Postman Collection Runner is that it can only execute collection in a consecutive way. This is just a simple implementation of the solution explained in this StackOverflow conversation.

Create your Postman Collection and corresponding tests

Here I needed to attack first /api/persons to get the list of persons ids.

/api/persons

And then /api/persons/:id for each person in the list.

/api/persons/:id

To do that I used the postman.setNextRequest() tricks that specify the next request that will be executed in the collection run. And in each run I get the last personId and pop() it from the array in environment variables.

Export your collection and the environment variables

/api/persons/:id

And save the files in a postman/ directory.

Create the new npm project

Simply run npm init -y and install the 3 dependencies: npm i async newman path

{
  "name": "newman_parallel",
  "version": "1.0.0",
  "description": "",
  "main": "index.js",
  "scripts": {
    "start": "node index.js"
  },
  "keywords": [],
  "author": "",
  "license": "ISC",
  "dependencies": {
    "async": "^3.1.0",
    "newman": "^4.5.6",
    "path": "^0.12.7"
  }
}

The script !

It’s kind of self explanatory, update the path for your postman collection and environment, specify the number of concurrent run you want to launch with the constant PARALLEL_RUN_COUNT and execute the script with npm start

const path = require('path')
const async = require('async')
const newman = require('newman')
const PARALLEL_RUN_COUNT = 2
const parametersForTestRun = {
    collection: path.join(__dirname, 'postman/postman_collection.json'), // your collection
    environment: path.join(__dirname, 'postman/localhost.postman_environment.json'), //your env
    reporters: 'cli'
};
parallelCollectionRun = function (done) {
    newman.run(parametersForTestRun, done);
};
let commands = []
for (let index = 0; index < PARALLEL_RUN_COUNT; index++) {
    commands.push(parallelCollectionRun);
}
// Runs the Postman sample collection thrice, in parallel.
async.parallel(
    commands,
    (err, results) => {
        err && console.error(err);
        results.forEach(function (result) {
            var failures = result.run.failures;
            console.info(failures.length ? JSON.stringify(failures.failures, null, 2) :
                `${result.collection.name} ran successfully.`);
        });
    });

newman

And here you can play around with your api and build some stress tests to see how it handles the pressure. You can find the code in the Github repo.