Automating PHD Notifications

A customer is trying to automate the PHD notifications using Health API. Here is a scenario they are trying to achieve.

Create a CW Event Rule for a Schedule Notification for all the Services.

They are able to do it for an individual service (EC2, RDS, DX etc) but not for all services as the Dropdown only allows to select one service. I advised them that they could use Custom Event pattern option instead of going for dropdown approach to do something like this. But they are asking if there is a way to test it. Is there a way to add dummy PHD notifications for test? If not, Is there a way we could solve this use case for the customer?

Here is the custom event pattern I suggested:

'{
  "source": [
"aws.health"
  ],
  "detail-type": [
    "AWS Health Event"
  ],
  "detail": {
    "eventTypeCategory": [
      "scheduledChange"
    ]
  }
}'