Testing an Apex Trigger Configured with Parallel Subscriptions

You can test an Apex platform event trigger that’s configured with parallel subscriptions the same way that you test a regular Apex platform event trigger.

See Testing Your Platform Event in Apex.

To verify that a trigger is configured for parallel subscriptions, run a query on EventBusSubscriber and select the IsPartitioned field. A value of true means that the trigger uses parallel subscriptions.

This example shows a sample query that gets all Apex trigger subscribers that are subscribed to the Order_Event__e platform event. The IsPartitioned field is one of the fields returned.

1SELECT ExternalId, Name, Position, Status, IsPartitioned FROM EventBusSubscriber 
2WHERE Topic='Order_Event__e' AND Type='ApexTrigger'

Sample query result:

ExternalID
01qZ70000008PWi
Name
MyOrderEventTrigger
Position
179
Status
Running
IsPartitioned
true

See EventBusSubscriber in the Object Reference for the Salesforce Platform.