Refactor validation exceptions

force-app/main/default/classes/OpportunityTriggerHandler.cls

@@ -0,0 +1,9 @@
+public with sharing class OpportunityTriggerHandler {
+
+    public static void run(List<Opportunity> newList, Map<Id, Opportunity> oldMap) {
+        if (Trigger.isBefore) {
+            OpportunityValidationService.validateStageProbability(newList);
+            OpportunityValidationService.validateDiscount(newList);
+        }
+    }
+}

force-app/main/default/classes/OpportunityValidationService.cls

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+public with sharing class OpportunityValidationService {
+
+    public static void validateStageProbability(List<Opportunity> opps) {
+        for (Opportunity opp : opps) {
+            if (opp.StageName == 'Closed Won' && opp.Probability < 100) {
+                opp.addError('Probability must be 100% when Stage is Closed Won.');
+            }
+        }
+    }
+
+    public static void validateDiscount(List<Opportunity> opps) {
+        for (Opportunity opp : opps) {
+            if (opp.Discount__c != null && opp.Discount__c > 50) {
+                opp.addError('Discount cannot exceed 50%.');
+            }
+        }
+    }
+}

force-app/main/default/classes/OpportunityValidationServiceTest.cls

@@ -0,0 +1,53 @@
+@isTest
+private class OpportunityValidationServiceTest {
+
+    @isTest
+    static void testInvalidStageProbability() {
+        Opportunity opp = new Opportunity(
+            Name = 'Test Opp',
+            StageName = 'Closed Won',
+            Probability = 80,
+            CloseDate = Date.today()
+        );
+
+        Test.startTest();
+        Database.SaveResult sr = Database.insert(opp, false);
+        Test.stopTest();
+
+        System.assert(!sr.isSuccess());
+    }
+
+    @isTest
+    static void testInvalidDiscount() {
+        Opportunity opp = new Opportunity(
+            Name = 'Discount Test',
+            StageName = 'Prospecting',
+            Probability = 10,
+            Discount__c = 60,
+            CloseDate = Date.today()
+        );
+
+        Test.startTest();
+        Database.SaveResult sr = Database.insert(opp, false);
+        Test.stopTest();
+
+        System.assert(!sr.isSuccess());
+    }
+
+    @isTest
+    static void testValidOpportunity() {
+        Opportunity opp = new Opportunity(
+            Name = 'Valid Opp',
+            StageName = 'Prospecting',
+            Probability = 10,
+            Discount__c = 20,
+            CloseDate = Date.today()
+        );
+
+        Test.startTest();
+        insert opp;
+        Test.stopTest();
+
+        System.assertNotEquals(null, opp.Id);
+    }
+}

force-app/main/default/classes/exceptions/OpportunityValidationException.cls

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+public class OpportunityValidationException extends ValidationException {
+}

force-app/main/default/classes/exceptions/OpportunityValidationException.cls-meta.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<ApexClass xmlns="http://soap.sforce.com/2006/04/metadata">
+    <apiVersion>59.0</apiVersion>
+    <status>Active</status>
+</ApexClass>
+

force-app/main/default/classes/exceptions/ValidationException.cls

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+public class ValidationException extends Exception {
+}

force-app/main/default/classes/exceptions/ValidationException.cls-meta.xml

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+<?xml version="1.0" encoding="UTF-8"?>
+<ApexClass xmlns="http://soap.sforce.com/2006/04/metadata">
+    <apiVersion>59.0</apiVersion>
+    <status>Active</status>
+</ApexClass>

force-app/main/default/triggers/OpportunityTrigger.trigger

@@ -0,0 +1,3 @@
+trigger OpportunityTrigger on Opportunity (before insert, before update) {
+    OpportunityTriggerHandler.run(Trigger.new, Trigger.oldMap);
+}