How to check if Change Detection was triggered on a component
<p>In my app I want to set manual change detection. For this I set the ChangeDetectionStrategry to OnPush and whenever a change occurs in a component I manually run change detection using detectChanges.</p>

<p>If I set ChangeDetectionStrategy to OnPush on a parent component, as per my understanding it will run change detection only once on the parent component and only once on the child component, even if I don't set ChangeDetectionStrategy to OnPush on child. If there is any change in the parent component, I run detectChanges() in parent component. And if there is any change in the child component, I run detectChanges() in child component.</p>

<p>Please suggest is it the correct way? or is there any better way?</p>

<p>Secondly, is there any way to check if its working as expect and no change detection is performed on a particular component.</p>