Writing Apex Test method for insert attachment

Salesforce.com makes it extremely easy to add attachments to any record either programmatically or from the UI. Writing a test case for the insert attachment is little tricky. Below are the quick apex code snippets for inserting an attachment for use in a Apex Text method. This would be useful for ensuring sufficient code coverage for the Apex classes that depend on insert attachment functionality. 

Version 1: with 1 argument (object Id of an object to which the attachment is added or the parentId of the attachment)

    /**

     * test method for add attachment to any object by passing the object Id

     */

    private static void testAddAttachmentToObject(Id objectId) {

    Blob b = Blob.valueOf('Test Data');

   

    Attachment attachment = new Attachment();

    attachment.ParentId = objectId;

    attachment.Name = 'Test Attachment for Parent';

    attachment.Body = b;

   

    insert(attachment);

     List<Attachment> attachments=[select id, name from Attachment where parent.id=: objectId];
     System.assertEquals(1, attachments.size());

    }

Version 2: without any arguments

    /**

     * test method for add attachment to any object by creating an object 

     */

    private static void testAddAttachmentToObject() {

        Account acct = new Account(Name='Test Account'); 

       /*

            you should supply values for all mandatory fields 

            same way, you can create any other object

      */

        insert acct;

     Blob b = Blob.valueOf('Test Data');

      

     Attachment attachment = new Attachment();

     attachment.ParentId = acct.Id;

     attachment.Name = 'Test Attachment for Parent';

     attachment.Body = b;

    

     insert(attachment);

     List<Attachment> attachments=[select id, name from Attachment where parent.id=: acct.Id];
     System.assertEquals(1, attachments.size());

    }

Hope this is helpful.