add wait test utility function

npm/ng-packs/packages/core/testing/src/lib/utils/index.ts

@@ -1 +1,2 @@
 export * from './clear-page.util';
+export * from './wait.util';

npm/ng-packs/packages/core/testing/src/lib/utils/wait.util.ts

@@ -0,0 +1,6 @@
+import { ComponentFixture } from '@angular/core/testing';
+
+export function wait<T extends any>(fixture: ComponentFixture<T>, timeout = 0) {
+  fixture.detectChanges();
+  return new Promise(res => setTimeout(res, timeout));
+}