How to implement intervals/polling in angular2 to

问题:

I have an angular2 app I want to test with protractor.

In this app I have a page with a graph that is being updated in regular intervals with autogenerated data.

Apparently one feature of protractor is waiting for scripts and http calls to finish before executing test code. However, if there is a constantly polling script that never finishes, protractor will wait forever and time out after a certain time.

In angular1 this could be solved by implementing the polling with $interval, which protractor does not wait for. Unfortunately in angular2 there is no $interval and the correct way to implement polling seems to be Observable.interval, so this is what my code looks like:

Observable.interval(500)
          .map(x => this.getRandomData())
          .subscribe(data => this.updateGraph(data));

When testing a page where this code is running, protractor will time out. It waits for the page to finish loading and thinks this script will exit sometime (when in fact it runs forever).

• Is there an interval mechanism in angular2 that protractor recognizes, so that it doesn't wait for the polling to finish before running the UI tests?

• If not, how can I tell protractor not to wait for this interval to finish before executing more test code?

EDIT: To clarify, the timeout problem already existed in protractor with angular1, but could be fixed by using $interval, see:

• Timed out waiting for Protractor to synchronize with the page after 50001ms
• How to implement intervals in protractor/selenium

This doesn't work in angular2 because there is no $interval.

回答1:

After some investigation, I found two possible solutions:

1. browser.ignoreSynchronization = true instructs protractor to stop waiting for http calls and interval scripts. However, this will likely make writing e2e tests much harder, because now you have to manually wait for elements and pages to load before testing them.
2. The protractor-xhr-only plugin basically does the same thing as ignoreSynchronization, but only for interval scripts. Protractor will still wait for $http calls to finish.

Neither of both are a perfect solution, but better than nothing.

回答2:

https://github.com/angular/protractor/issues/3349#issuecomment-232253059

resolved this problem with help from juliemr:

this.ngZone.runOutsideAngular(() => {
  this.timer = Observable.interval(1000)
}

run timeout out of zone, then protractor will not wait for it.