Queueable, class implementing interface
DOC > https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_queueing_jobs.htm
Sample >
@isTest(SeeAllData = true) static void executeTest9(){
// Set mock callout class
Test.setMock(HttpCalloutMock.class, new AsyncExecutionExampleMockImpl());
//Insert in DB the object that the job will process (eg: 'quote')
Test.startTest();
System.enqueueJob(new AsyncExecutionExample(quote.policyN__c));
Test.stopTest();
}