test(store): ensure Actions stream leave NGXS execution strategy an…

…d cause CDs (#1936)

packages/store/tests/issues/actions-stream-causing-ticks.spec.ts

@@ -0,0 +1,78 @@
+import { Component, NgModule, ApplicationRef } from '@angular/core';
+import { BrowserModule } from '@angular/platform-browser';
+import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
+import { take } from 'rxjs/operators';
+import {
+  Action,
+  Actions,
+  NgxsModule,
+  ofActionSuccessful,
+  State,
+  StateContext,
+  Store
+} from '@ngxs/store';
+import { freshPlatform, skipConsoleLogging } from '@ngxs/store/internals/testing';
+
+describe('Actions stream causing ticks', () => {
+  class SetCountries {
+    static readonly type = '[CountriesState] Set countries';
+
+    constructor(readonly countries: string[]) {}
+  }
+
+  @State<string[]>({
+    name: 'countries',
+    defaults: []
+  })
+  class CountriesState {
+    @Action(SetCountries)
+    async setCountries(ctx: StateContext<string[]>, action: SetCountries) {
+      await Promise.resolve();
+      ctx.setState(action.countries);
+    }
+  }
+
+  @Component({
+    selector: 'app-root',
+    template: '<button id="set-countries" (click)="setCountries()">Set countries</button>'
+  })
+  class TestComponent {
+    constructor(private _store: Store, actions$: Actions) {
+      // Create 10 subscriptions in a row.
+      Array.from({ length: 10 }).forEach(() => {
+        actions$.pipe(ofActionSuccessful(SetCountries)).subscribe();
+      });
+    }
+
+    setCountries(): void {
+      this._store.dispatch(new SetCountries(['USA']));
+    }
+  }
+
+  @NgModule({
+    imports: [BrowserModule, NgxsModule.forRoot([CountriesState])],
+    declarations: [TestComponent],
+    bootstrap: [TestComponent]
+  })
+  class TestModule {}
+
+  it(
+    'should run many change detections when the Actions stream is subscribed',
+    freshPlatform(async () => {
+      // Arrange
+      const { injector } = await skipConsoleLogging(() =>
+        platformBrowserDynamic().bootstrapModule(TestModule)
+      );
+      const actions$ = injector.get(Actions);
+      const appRef = injector.get(ApplicationRef);
+      jest.spyOn(appRef, 'tick');
+
+      // Act
+      document.getElementById('set-countries')!.click();
+      await actions$.pipe(ofActionSuccessful(SetCountries), take(1)).toPromise();
+
+      // Assert
+      expect(appRef.tick).toHaveBeenCalledTimes(12);
+    })
+  );
+});