how to automate this test set up

Question

I am trying to setup test data for a test class. I want to do a loop and populate the trn.Training_Resource__c field with unique name, record ID from the trL Training_Resource__c object instead of hard coding a name ,'a1ZG000000CoOui' and then having to have multiple insert lines.

How to do it? BTW, is this the correct way to setup test data?

Thanks

 List <Training_Resource__c> trL = New List<Training_Resource__c>();
    Integer x;
    for (x=1;x<3;x++)
    {    
        Training_Resource__c tr = New Training_Resource__c();
        tr.Name = 'Test'+x;
        trL.add(tr);
    }
    insert trL;

    Training__c trn = New Training__c();
    trn.Name = 'A 1';
    trn.Training_Resource__c='a1ZG000000CoOui';

    Training__c trn2 = New Training__c();
    trn2.Name = 'A 2';
    trn2.Training_Resource__c='a1ZG000000CoOui';
    insert trn;
    insert trn2;  

Answer 1

Dont hardcode your parent record id. Use the ids in the first list you inserted ie. Instead of hardcoded id, reference trL[0].id , trL[1].id etc.

Answer 2

As an alternative

 List <Training_Resource__c> trL = new List<Training_Resource__c> {
       new Training_Resource__c(name = '00Test'),
       new Training_Resource__c(name = '01Test')};
 insert trL;

 List<Training__c> trnL = new List<Training__c> {
      new Training__c(name = 'A 1', training_resource__c = trl[0].id),
      new Training__c(name = 'A 2', training_resource__c = trl[1].id)};
 insert trnL;