@isTest
private class updateOpportunityActivityTest {
    
    static testmethod void updateOpportunityActivityFieldsFromTask() {
    
        User u = new User(
            Alias = 'batman',
            Email='bruce.wayne@mytestorg123.com',
            EmailEncodingKey='UTF-8',
            LastName='Wayne',
            LanguageLocaleKey='en_US',
            LocaleSidKey='en_US',
            ProfileId = [Select Id From Profile Where Name='System Administrator'],
            TimeZoneSidKey='America/Los_Angeles',
            UserName='bruce.wayne@mytestorg123.com',
            UserRoleId = [Select Id From UserRole Where Name='ADM']
        );
        insert u;

        //Declare the  task up  here, because we are going to use System.assert against it, outside of the System.runAs code block.
        System.runAs(u){
            Account acc = new Account(Name='Tester 18');
            insert acc;
        
            Opportunity opp = new Opportunity(
                Name = 'Test Oppty',
                Amount = 5,
                CloseDate = system.now().date(),  
                AccountId = acc.Id,
                StageName = 'Stage 0: Scheduled'
            );
            insert opp;
        
            //Since we are testing the task trigger, use Test.startTest here to reset all the DML limits, etc.
            Test.startTest();
            Task tsk = new Task(
                 WhatId = opp.Id,
                 Subject = 'Test 18',
                 Type = 'Call'
             );
             insert tsk;
             Test.stopTest();
        }

        //Begin assertion logic, to make sure our trigger performed as expected....
        Task t = [Select CreatedDate From Task];

        Opportunity o = [Select Last_Sales_Activity__c, Last_Sales_Activity_Type__c From Opportunity];

        System.assertEquals(t.CreatedDate,o.Last_Sales_Activity__c);
        System.assertEquals('Call',o.Last_Sales_Activity_Type__c);
    }
}