New Record Trigger:

New Record Trigger:
This post regarding how to create a new case when ever customer shop visit .Here shop visit is a custom object so trigger looks like this
Apex Trigger:
trigger createCaseFromBroker on ShopVisit__c (after insert) {
    
    List<Group> sfdcGroup = [select Id, name from Group where Name = 'Support Queue' limit 1];

        if(Trigger.new.size() == 1){
        for(ShopVisit__c b:Trigger.new){
          //for each broker, b, create a new DueDiligence case
              Case newCase = new Case(
                Subject = 'Perform Due Diligence',
                shopvisit__c = b.Id,
                Status = 'Open',
                Priority = 'Medium',
                Category__c = 'Pre-Approval',
                Subcategory__c = 'How to become a Broker',
                Origin = 'Web'  //is there an origin? required in UI
              );
              
              //if broker has a primary contact
              if(b.Primary_Contact__c != null){
                  newCase.ContactId = b.Primary_Contact__c;
              }
              if(!sfdcGroup.isEmpty()){
                  newCase.OwnerId = sfdcGroup[0].Id;
              }
              insert newCase;
        }                  
        } 
}


Test Class:
public class CreateCase {

  static testMethod void test_createCaseFromBroker(){
      
      //create contact record
      Contact contact = new Contact();
      contact.FirstName = 'Test 1 - contact';
      contact.LastName = 'Dummy';
      insert contact;
      String contactId = contact.Id;
      
    //create broker record #1
    shopvisit__c broker1 = new shopvisit__c();
    broker1.Name = 'Test 1 - broker';
 
    broker1.Primary_Contact__c = contactId;

    insert broker1;
    String broker1Id = broker1.Id;
    
    //validate case was created
    List<Case> bsCase = [
        SELECT Id,Shopvisit__c
            FROM case 
            WHERE shopvisit__c = :broker1Id
            LIMIT 1
        ];
    for( Case c:bsCase ){
        System.assertEquals(broker1Id,c.shopvisit__c);
    }
    
    
  }
  
}