afv-library/prompts/apex-development/trigger-refactoring.md

name	description	tags	requires_deploy	setup_summary
Trigger Refactor Helper	Refactor the Opportunity trigger into a handler pattern with tests	apex, refactor, testing	true	Deploy baseline trigger to target org before running instructions

Setup

1. Deploy the baseline trigger shown below to your default or scratch org.
2. Confirm the trigger compiles successfully before continuing.

// ❌ Anti-pattern: all logic stuffed into the trigger, with DML/SOQL in loops.
trigger OpportunityTrigger on Opportunity (before insert, before update, after update) {
    // BEFORE INSERT: validate Closed Won w/ low Amount
    if (Trigger.isBefore && Trigger.isInsert) {
        for (Opportunity o : Trigger.new) {
            if (o.StageName == 'Closed Won' && (o.Amount == null || o.Amount < 1000)) {
                o.addError('Closed Won opportunities must have Amount ≥ 1000.');
            }
        }
    }

    // BEFORE UPDATE: if Stage changed, overwrite Description
    if (Trigger.isBefore && Trigger.isUpdate) {
        for (Opportunity o : Trigger.new) {
            Opportunity oldO = Trigger.oldMap.get(o.Id);
            if (o.StageName != oldO.StageName) {
                o.Description = 'Stage changed from ' + oldO.StageName + ' to ' + o.StageName;
            }
        }
    }

    // AFTER UPDATE: when Stage becomes Closed Won, create a follow-up Task
    if (Trigger.isAfter && Trigger.isUpdate) {
        for (Opportunity o : Trigger.new) {
            Opportunity oldO = Trigger.oldMap.get(o.Id);
            if (o.StageName == 'Closed Won' && oldO.StageName != 'Closed Won') {
                Task t = new Task(
                    WhatId     = o.Id,
                    OwnerId    = o.OwnerId,
                    Subject    = 'Send thank-you',
                    Status     = 'Not Started',
                    Priority   = 'Normal',
                    ActivityDate = Date.today()
                );
                insert t; // ❌ DML in a loop
            }
        }
    }
}

Instructions

Refactor OpportunityTrigger into a handler class (or classes) that handles the same behavior using bulk-safe patterns. Ensure the trigger itself delegates and remains behaviorally identical.

Testing & Reporting

• Create unit tests covering positive and negative paths for each handler method.
• Include a bulk test that updates 50 Opportunity records where only half qualify for the after update logic.
• Deploy the refactored code and run the tests, then report coverage and key observations.