When waiting for services to be ready, or when polling for long-running job results, I see 4 basic options:
- Use Postman collection runner or newman and set a per-step delay. This delay is inserted between every step in the collection. Two challenges here: it can be fragile unless you set the delay to a value the request duration will never exceed, AND, frequently, only a small number of steps need that delay and you are increasing total test run time, creating excessive build times for a common build server delaying other pending builds.
- Use
https://postman-echo.com/delay/10 where the last URI element is number of seconds to wait. This is simple and concise and can be inserted as a single step after the long running request. The challenge is if the request duration varies widely, you may get false failures because you didn't wait long enough.
- Retry the same step until success with
postman.setNextRequest(request.name);. The challenge here is that Postman will execute the request as fast as it can which can DDoS your service, get you black-listed (and cause false failures), and chew up a lot of CPU if run on a common build server - slowing other builds.
- Use setTimeout() in a Pre-request Script. The only downside I see in this approach is that if you have several steps needing this logic, you end up with some cut & paste code that you need to keep in sync
Note: there are minor variations on these - like setting them on a collection, a collection folder, a step, etc.
I like option 4 because it provides the right level of granularity for most of my cases. Note that this appears to be the only way to "sleep" in a Postman script. Now standard javascript sleep methods like a Promise with async and await are not supported and using the sandbox's lodash _.delay(function() {}, delay, args[...]) does not keep script execution on the Pre-request script.
In Postman standalone app v6.0.10, set your step Pre-request script to:
console.log('Waiting for job completion in step "' + request.name + '"');
// Construct our request URL from environment variables
var url = request['url'].replace('{{host}}', postman.getEnvironmentVariable('host'));
var retryDelay = 1000;
var retryLimit = 3;
function isProcessingComplete(retryCount) {
pm.sendRequest(url, function (err, response) {
if(err) {
// hmmm. Should I keep trying or fail this run? Just log it for now.
console.log(err);
} else {
// I could also check for response.json().results.length > 0, but that
// would omit SUCCESS with empty results which may be valid
if(response.json().meta.status !== 'SUCCESS') {
if (retryCount < retryLimit) {
console.log('Job is still PENDING. Retrying in ' + retryDelay + 'ms');
setTimeout(function() {
isProcessingComplete(++retryCount);
}, retryDelay);
} else {
console.log('Retry limit reached, giving up.');
postman.setNextRequest(null);
}
}
}
});
}
isProcessingComplete(1);
And you can do your standard tests in the same step.
Note: Standard caveats apply to making retryLimit large.
