Integration testing of @Effect() observables

[dinvlad]

I'm submitting a...

[ ] Regression (a behavior that used to work and stopped working in a new release)
[ ] Bug report  
[x] Feature request
[ ] Documentation issue or request

What is the current behavior?

One is able to unit-test individual effect observables.

Expected behavior:

We should be able to test that these observables are properly registered with the store (i.e. provide an integration test). For example, an observable may be provided and behave correctly in isolation, but a developer can forget or accidentally remove a corresponding @Effect decorator.

We should also be able to test that the decorator has been configured correctly. E.g. to test that "dispatch: false" was set.

Although we can indeed instantiate the "real" store and subscribe to its Actions, actions returned from effects in this way don't get "immediately" dispatched in a test. As a result, it is unclear how to "wait" until a particular effect "settled down" before testing whether this effect resulted in a dispatch of a new action, or whether no dispatch happened (if "dispatch: false").

If that's possible to achieve with the current implementation, could you provide an example how to?

Minimal reproduction of the problem with instructions:

https://github.com/ngrx/platform/blob/master/example-app/app/auth/effects/auth.effects.ts

Version of affected browser(s),operating system(s), npm, node and ngrx:

any

Other information:

[dinvlad]

As a possible solution, we could expose

platform/modules/effects/src/effects_metadata.ts

Lines 42 to 45 in 100a8ef

	export const getSourceMetadata = compose(
	getEffectMetadataEntries,
	getSourceForInstance
	);

getSourceMetadata() returns all of the necessary information to enable these tests.

Moreover, we can then get by with simple unit tests, and the integration test will consist of a single
expect(TestBed.get(EffectsClass)).toBeDefined() when TestBed imports an entire store module.

Currently, we can

import { getSourceMetadata } from '@ngrx/effects/src/effects_metadata';

but I assume that is not reliable as it's not exposed through the API?
I can submit a PR to export it through @ngrx/effects/testing.