Add support for `waitForTasksOutsideAngular` in protractor tests

[mmalerba]

Currently this has only been implemented in TestbedHarnessEnvironment, it should be implemented for ProtractorHarnessEnvironment too. I think we can reuse the same infrastructure we created to deal with this in unit tests, but just run it as a browser script in protractor. See #18361 for some additional discussion

[LayZeeDK]

Is this useful?

https://github.com/angular/blocking-proxy

[mmalerba]

Hmm, I'm not familiar with the blocking proxy, you're welcome to experiment with it and see if it helps. Like I mentioned above, I'm pretty sure we can just reuse the work we did for TestbedHarnessEnvironment, I just haven't had time to look into it yet.

[devversion]

The blocking proxy is definitely interesting, but probably not needed as we do not want to intercept all webdriver commands IIRC. At first glance, I'm thinking we will execute a client side script (similar to what bocking proxy does), but then only connect to it when we call waitForTasksOutsideAngular in the harness environment.

We should look into this, but also start running harness tests with the protractor test environment.

[tobiasschweizer]

I have a use case involving MatAutocomplete: the options are fetched from the server as the user types into the input field.
Since this is async, the options will only be there once the answer from the server has been received and can be displayed in the template, see https://community.indepth.dev/t/create-a-component-harness-for-your-tests-with-angular-cdk/293/4?u=tobi.

Would calling waitForTasksOutsideAngular on MatAutocompleteHarness (when implemented) ensure that the async action has been successfully completed and that the MatOptions can be expected to be present?

[devversion]

@tobiasschweizer Yeah, that should do the trick. Assuming that the data fetching happens within runOutsideAngular. Is that the case here?