Unit Testing Batch Delete Class

Question

I have a batch class that is used to clear out all the records of an object. I'm trying to unit test the case where one of the records fails to be deleted. I'm trying to have a record fail by locking it in my unit test.

public static testMethod void testDeleteFailure() {
  //Test data is setup and I have various assertions here to make sure my test data is good

  Test.StartTest();
  List<My_Object__c> lockedItems = [SELECT Id FROM My_Object__c LIMIT 2 FOR UPDATE];
  BatchDeleteObject deleteJob = new BatchDeleteObject('My_Object__c');
  Database.executeBatch(deleteJob);
  Test.StopTest();

  Integer newCount = [SELECT COUNT() FROM My_Object__c];
  System.assertEquals(lockedItems.count(), newCount, 'There should be ' + lockedItems.count() + ' still in the database.');
}

However, my records aren't locking so they are being deleted just fine. Is there another way to lock these records? Is there a better way to test to make sure any failures are handled appropriately?

Answer 1

I recommend you break your logic into smaller, more testable chunks so you can more easily test just your handling of DmlException. Then you can apply a technique like deleting the records before passing them into the method.

Your batch would look something like the following plus/minus the rest of your logic:

public void execute(BatchableContext context, List<SObject> records)
{
    MyObjectService.safeDelete(records);
}

Then your test would do something like:

@IsTest void testSafeDelete() { /*happy path*/ }
@IsTest
static void testSafeDelete_DmlException()
{
    List<MyObject__c> records = new List<MyObject__c>();
    // add some data
    insert records;
    delete records;

    Test.startTest();
        MyObjectService.safeDelete(records);
    Test.stopTest();

    // assert on behavior
}

Answer 2

Posting separately since it's so wildly different. This approach forces you to make your batch stateful, so I would avoid it unless your batch is already marked as such.

---

Another option would be to invoke some sort of proxy.

public virtual class DmlProxy
{
    public virtual void insertRecords(List<SObject> records) { insert records; }
    public virtual void updateRecords(List<SObject> records) { update records; }
    public virtual void deleteRecords(List<SObject> records) { delete records; }
    public virtual void undeleteRecords(List<SObject> records) { undelete records; }
}

Have your batch class store the type and construct it dynamically.

public class MyBatch
{
    @TestVisible Type proxyType = DmlProxy.class;
    //...
    public void execute(/*params*/)
    {
        DmlProxy proxy = (DmlProxy)proxyType.newInstance();
        proxy.deleteRecords(scope);
    }
    //...
}

Then in your test class you can define a separate proxy to use, and inject that dependency.

class FailDelete extends DmlProxy
{
    public override void deleteRecords(List<SObject> records)
    {
        throw new DmlException();
    }
}
@IsTest static void testMyBatch_DmlException()
{
    //data setup

    Test.startTest();
        MyBatch batch = new MyBatch();
        batch.proxyType = FailDelete.class;
        Database.executeBatch(batch);
    Test.stopTest();

    // assertions
}