HI All,

Anyone please help me with the trigger,  basically it fires on insert and works if a user with username 'abc@abc.com'' assigns a new task to anyone other than the owner of the task it will be automatically assigned to the owner of the task.

THe issue is i don't have any unit test failure but when i validate the code it throws following error."Failure Message: "System.QueryException: List has no rows for assignment to SObject", Failure Stack Trace: "Class.Task_AssignOwnerTest.test: line 51, column 1"

i could put a if(User.size()==0) then return;

but to do this i need to do below change: 

User[] user = [
select Id, ProfileID
from User
where IsActive = true
and username = 'abc@abc.com'
limit 1
];

and if i do above changes then i am not able to runAs (User[0].id) .

as the error is "runAs requires single argument of type 'user'"

Below is the test class

@IsTest
private class Task_AssignOwnerTest {
public static Program__c program1 = [select Id from Program__c limit 1];

@IsTest
public static void test() {
User[] userList = [
select UserRoleId
from User
where Profile.Name = 'System Administrator'
and UserRoleId != null
and IsActive = true
limit 3
];

Account account = new Account();
account.name = 'Testing account';
account.ownerId = userList[0].Id;
insert account;
System.debug(' ::Task_AssignOwnerTest:: step 1' +account.Id);

Contact contact = new Contact();
contact.FirstName = 'FirstName';
contact.Start_Term__c = 'Jan 2011';
contact.LastName = 'LastName';
contact.Program_Primary__c = program1.Id;
contact.OwnerId = userList[0].Id;
contact.AccountId = account.Id;
insert contact;
System.debug(' ::Task_AssignOwnerTest:: step 2' +contact.Id);

Opportunity opportunity = new Opportunity();
opportunity.Contact__c = contact.Id;
opportunity.Name = 'OpportunityName';
opportunity.StageName = 'StageName';
opportunity.CloseDate = Date.today();
opportunity.Program__c = program1.Id;
opportunity.OwnerId = userList[0].Id;
insert opportunity;
System.debug(' ::Task_AssignOwnerTest:: step 3' +opportunity.Id);

(Line 51 is here)User user = [
select Id, ProfileID
from User
where IsActive = true
and username = 'abc@abc.com'
limit 1
];

 System.debug(' ::Task_AssignOwnerTest:: step 4' +user[0].id);

try {
System.RunAs(user){
Task[] taskList = new Task[] {
new Task (WhoId = contact.Id, OwnerId = userList[1].Id),
new Task (WhoId = null),
new Task (WhoId = opportunity.Id, OwnerId = userList[1].Id)
};
insert taskList;
}
} catch (System.dmlException e) {

}

}
}