Best Apex Test Class Example for Beginners in Salesforce

Trigger :

1. trigger RestrictInvoiceDeletion on Invoice_Statement__c (before delete)
2. {
3.     // With each of the invoice statements targeted by the trigger and that have line items, add an error to prevent them from being deleted.
4.     for (Invoice_Statement__c invoice :[SELECT Id
5.                                         FROM Invoice_Statement__c WHERE Id IN (SELECT Invoice_Statement__c FROM Line_Item__c) AND Id IN :Trigger.old])
6.     {
7.         Trigger.oldMap.get(invoice.Id).addError('Cannot delete invoice statement with line items');
8.     }
9. }

Line_Item__c is the Junction Object

Invoice_Statement__c  is the Master Detail Relationship

Screenshot for the Relationship

Test Data Factory

Create a Test Data factory class instead of every time creating records in test class.

1. @isTest
2. public class TestDataFactory
3. {
4.     public static Invoice_Statement__c createInvoice(boolean inv)
5.     {
6.         Invoice_Statement__c invoice=createInvoice();
7.        
8.         if(inv==true)
9.         {
10.             Merchandise__c me=createMerchandise();
11.             createLineItem(invoice,me);
12.         }
13.        
14.         return invoice;
15.     }
16.    
17.     private static Merchandise__c createMerchandise()
18.     {
19.         Merchandise__c mer=new Merchandise__c(Name='Test',Description__c='test description',Price__c=1000,Total_Inventory__c=10);
20.         insert mer;
21.         return mer;
22.     }
23.    
24.     private static Invoice_Statement__c createInvoice()
25.     {
26.         Invoice_Statement__c invRec=new Invoice_Statement__c(Description__c='test description');
27.         insert invRec;
28.         return invRec;
29.     }
30.    
31.     private static Line_Item__c createLineItem(Invoice_Statement__c inv,Merchandise__c mer)
32.     {
33.         Line_Item__c li=new Line_Item__c(Invoice_Statement__c=inv.id,Merchandise__c=mer.Id,Unit_Price__c=mer.Price__c);
34.         insert li;
35.         return li;
36.     }
37. }

Test Class

1. @isTest
2. private class RestrictInvoiceDeleteTest
3. {
4.     static testMethod void nonDeletedData()
5.     {
6.         Invoice_Statement__c inv=TestDataFactory.createInvoice(true);
7.         Test.startTest();
8.        
9.         Database.DeleteResult delRes=Database.Delete(inv,false);
10.        
11.         Test.stopTest();
12.        
13.         System.assert(!delRes.isSuccess());
14.        
15.        
16.     }
17.     static testMethod void deletedData()
18.     {
19.         Invoice_Statement__c inv=TestDataFactory.createInvoice(false);
20.         Test.startTest();
21.        
22.         Database.DeleteResult delRes=Database.Delete(inv,false);
23.        
24.         Test.stopTest();
25.        
26.         System.assert(delRes.isSuccess());
27.        
28.     }
29.    
30.     static testMethod void testBulkDelete()
31.     {
32.         List<Invoice_Statement__c> invList=new List<Invoice_Statement__c>();
33.         invList.add(TestDataFactory.createInvoice(true));
34.         invList.add(TestDataFactory.createInvoice(false));
35.        
36.         Test.startTest();
37.         Database.DeleteResult[] delRec=Database.Delete(invList,false);
38.         Test.stopTest();
39.        
40.         System.assert(!delRec[0].isSuccess());
41.         System.assert(!delRec[1].isSuccess());
42.        
43.     }
44. }

Note: The above example provided by salesforce only. This example is very useful for beginners. If you have a doubts on this example please comment it.. I will help for you...!

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