Apex Test Class: Populate parent relationship in a Master-Detail

Question

I have the following code in a test class

parent__c parent = new parent__c();
insert parent;

child__c child = new child__c();
child.parent__c = parent.Id;
insert child;

In the DataBase, the relationship from the parent to the child is called child__r and it is populated for many records.

If I try

System.debug('@@@@@ --> '+[SELECT Id, parent__c FROM child__c]);

I get the child Id and parent Id correctly, but if I try

System.debug('@@@@@ --> '+[SELECT Id, (SELECT Id FROM child__r) FROM parent__c]);

Only the parent is returned, in other words, the relationship is not populated and

System.debug('@@@@@ --> ' + parent.child__r);

is empty.

In the tested class, an If statement has in the condition "!child__r.isEmpty()", how can I populate the relationship?

P.S. I cannot use isRunningTest() since then I could not enter in the ELSE statement.

Answer 1

I can't seem to reproduce your issue. But can explain a little bit what I have tried.

Below is a simple test method to reproduce your scenario:

@isTest
public class SampleUnitTest {
    @isTest
    public static void testSample() {
        Account acc = new Account();
        acc.Name = 'test acc';
        insert acc;

        Contact con = new Contact();
        con.accountId = acc.Id;
        con.lastName = 'tln';
        insert con;

        acc = [Select Id, Name, (Select Id From Contacts) From Account Where Id = :acc.Id];
        System.debug(acc);

        System.debug('Contacts are: ' + acc.Contacts);

        for(Contact c: acc.Contacts) {
            System.debug(c.Id);
        }
    }
}

Please note that if you debug acc, it doesn't show the contact information there.

However, if you use a do a System.debug(acc.Contacts) or do the debug inside a loop, it will print the related information out.

I am not quite sure whether you have tried both or only tried System.debug(acc). If the later one was the case, it simply doesn't mean your related list is empty.