ApprovalProcessorClass

public class ApprovalProcessor {

    webservice void submitAndProcessApprovalRequest() {

        // Create an approval request for the account
        Approval.ProcessSubmitRequest req1 = new Approval.ProcessSubmitRequest();
        
        req1.setComments('Submitting request for approval.');
        req1.setObjectId(a.id);
        
        // Submit on behalf of a specific submitter
        req1.setSubmitterId(user1.Id);
        
        // Submit the record to specific process and skip the criteria evaluation
        req1.setProcessDefinitionNameOrId('PTO_Request_Process');

        req1.setSkipEntryCriteria(true);

        // Submit the approval request for the account
        Approval.ProcessResult result = Approval.process(req1);

        // Verify the result
        System.assert(result.isSuccess());

        System.assertEquals(
            'Pending', result.getInstanceStatus(),
            'Instance Status'+result.getInstanceStatus());
         )