Write the test class as follows,

@isTest
private class OwnerCopyTrigger
{
	public static testmethod void testInsertAccount()
	{
		//Write the code for Insert a Account Record
		Account a1 = new Account();
		a1.Name = 'Account One';
		insert a1;
		
		//Then update the record
		Account a2 = [SELECT id, Name FROM Account WHERE id =: a1.Id];
		a2.Name = 'Account One Edited'
		update a2;
	}
}

 If a reply to a post answers your question or resolves your problem, please mark it as the solution to the post so that others may benefit.

@isTest public With sharing  class TestOwnerCopy

{    

   static testMethod void ideaBatchTest() 

   {   

Account acc1 = new Account(Name='Test1', OwnerId='005P0000000cYkP' );       

insert acc1;

Account acc2 = new Account(Name='Test2', OwnerId='005P0000000crxP' );       

insert acc2;

Set<id> ids= new set<id>();       

 ids.add(acc1.ownerid);       

 ids.add(acc2.ownerid);       

             List<User> usr= [Select name, id from User where id in:ids];       

           acc1.ownerid='005P0000000crxP';       

           update acc1;       

           acc2.ownerid='005P0000000cYkP';       

            update acc2;

}

}

After this, Go to Apex Test Execution, and select this class and run it and after that check the test coverage of your trigger.

If you still face any issue, let me know.

If this resolve your issue, please mark it as a solution.

Thanks!

Hi,
Try the below code as reference of test method:

@isTest

private class testTriggerinsert_Contact_Activity_1
{
public static testMethod void unitTestinsert_Contact_Activity()
{
Profile p = [select id from profile where name='System Administrator'];
User u1 = new User(alias = 'standt2', email='standarduser@test12.com',
emailencodingkey='UTF-8', lastname='Testing1', languagelocalekey='en_US',
localesidkey='en_US', profileid = p.Id,firstname='Heather',
timezonesidkey='America/Los_Angeles', username='standarduser@test12.com');
insert u1;
account temp=new account(Name ='ashish testing',Owner_2__c=u1.id);
insert temp;


}
}

Did this answer your question? If not, let me know what didn't work, or if so, please mark it solved. 

This is giving error on saving this.

Error: Compile Error: unexpected token: 'update' at line 14 column 8 

Test execution failed :

This trigger is to get Full name for OwnerID. on Account record.

Owner_2 is a lookup field from account object to user object.