Schedulable Apex Practice Problems

Problem Statement

Write a Schedulable Apex class DailyLeadCleanupScheduler that deletes Leads which were converted more than 90 days ago.

Requirements

• Implement Schedulable interface.
• execute(SchedulableContext sc): calculate a cutoff date 90 days in the past.
• Query Leads where IsConverted = true AND ConvertedDate < cutoff.
• Delete only when the list is non-empty.

Best Practices

• Guard DML with if (!staleLeads.isEmpty()).
• Use a bind variable (:cutoff) — never concatenate dates into SOQL strings.
• SOQL outside any loop.

How to Schedule

String cron = '0 0 1 * * ?'; // 1 AM daily
System.schedule('Daily Lead Cleanup', cron, new DailyLeadCleanupScheduler());

Problem Statement

Write MonthlyAccountBatchScheduler that implements Schedulable and launches AccountRevenueTierBatch with a batch size of 200 when fired.

Requirements

• Implement Schedulable.
• Declare a @TestVisible private Integer batchSize = 200 instance variable.
• execute(): instantiate AccountRevenueTierBatch and call Database.executeBatch(batch, batchSize).

Best Practices

• Use @TestVisible so tests can override the batch size without exposing it publicly.
• Separate scheduler and batch classes — never mix Schedulable and Batchable in one class.
• Always specify batch size in executeBatch to avoid the default 200 silently changing behaviour.

How to Schedule

// Run at midnight on the 1st of every month
System.schedule('Monthly Account Batch', '0 0 0 1 * ?', new MonthlyAccountBatchScheduler());

Problem Statement

Write QuarterlyPipelineScheduler that implements Schedulable and sends an email summarising open Opportunities closing this quarter, grouped by stage.

Requirements

• Implement Schedulable.
• Declare @TestVisible private String recipientEmail.
• execute(): run an aggregate SOQL with StageName, COUNT(Id), SUM(Amount) filtered by IsClosed = false AND CloseDate = THIS_QUARTER.
• Build a plain-text body by looping the AggregateResult list.
• Send via Messaging.SingleEmailMessage.
• Wrap everything in try-catch(Exception e) with System.debug on error.

Best Practices

• THIS_QUARTER is a SOQL date literal — no manual date arithmetic needed.
• Use @TestVisible so tests can override the email address without making it public.
• Always wrap Messaging.sendEmail in try-catch — email limits can throw.

Problem Statement

Write HourlyMonitorScheduler that:

1. Marks overdue open Opportunities (CloseDate < today) as at-risk by setting At_Risk__c = true.
2. Self-reschedules for the next hour using a helper method buildNextHourCron().

Requirements

• Implement Schedulable.
• Declare @TestVisible static final String JOB_NAME.
• Business logic in a try block; self-reschedule in finally guarded by !Test.isRunningTest().
• buildNextHourCron(): returns a cron expression for the next hour (@TestVisible private static String).
• SOQL and DML outside loops; isEmpty() guard before DML.

Best Practices

• Use finally for self-reschedule — it runs even when the business logic throws.
• !Test.isRunningTest() prevents infinite scheduling in unit tests.
• Unique job name per run (append timestamp) prevents duplicate job name errors.

Problem Statement

Write DailyLeadCleanupScheduler that implements Schedulable and launches a LeadScoreResetBatch each time it fires. The batch size must be configurable via a @TestVisible field so tests can override it.

Requirements

1. Implement the Schedulable interface.
2. Declare @TestVisible private Integer batchSize = 200.
3. execute(SchedulableContext sc) — instantiate LeadScoreResetBatch and call Database.executeBatch(batch, batchSize).

Best Practices

• Always use a named local variable for the batch instance — readable and debuggable.
• @TestVisible on batchSize lets tests inject a smaller size without exposing the field publicly.
• Schedule: System.schedule('DailyLeadCleanup', '0 0 2 * * ?', new DailyLeadCleanupScheduler());

Problem Statement

Write EndOfMonthContractScheduler that runs on a schedule, counts all Activated Contracts expiring this month, and sends a summary email to a configurable recipient.

Requirements

1. Implement Schedulable.
2. Declare @TestVisible private String recipientEmail = 'admin@salesforce.com'.
3. execute():
   • COUNT query: SELECT COUNT() FROM Contract WHERE EndDate = THIS_MONTH AND Status = 'Activated'.
   • Build a Messaging.SingleEmailMessage with setToAddresses, setSubject, setPlainTextBody.
   • Guard Messaging.sendEmail() with !Test.isRunningTest().
   • Always System.debug the summary.

Problem Statement

Write WeeklyAccountSummaryScheduler that queries the total number and dollar value of Closed Won Opportunities for the current week using an AggregateResult query, then sends a formatted summary email.

Requirements

1. Implement Schedulable.
2. Declare @TestVisible private String recipientEmail.
3. execute():
   • Aggregate query: SELECT COUNT(Id) cnt, SUM(Amount) totalAmount FROM Opportunity WHERE IsWon = true AND CloseDate = THIS_WEEK.
   • Extract: (Integer) results[0].get('cnt') and (Decimal) results[0].get('totalAmount').
   • Null-guard totalAmount (set to 0 if null).
   • Build and send email (guard with !Test.isRunningTest()).

Key Concept: AggregateResult

Aggregate SOQL (with COUNT, SUM, AVG etc.) returns AggregateResult[]. Use result.get('alias') and cast to the expected type to read each column.

Problem Statement

Write ConditionalBatchScheduler that checks the current volume of unconverted Leads and launches LeadScoreResetBatch with a smaller batch size (100) under high load, and a larger batch size (200) under normal load.

Requirements

1. Implement Schedulable.
2. Declare @TestVisible static final Integer THRESHOLD = 1000.
3. execute():
   • COUNT query: SELECT COUNT() FROM Lead WHERE IsConverted = false.
   • If leadCount > THRESHOLD: batchSize = 100; else batchSize = 200.
   • System.debug the count and chosen batch size in both branches.
   • Database.executeBatch(new LeadScoreResetBatch(), batchSize).

Why Adaptive Batch Sizes?

Smaller chunks reduce governor limit risk under heavy load. Larger chunks mean fewer async jobs under normal volume.

Problem Statement

Write AdaptiveReschedulingScheduler that checks open Cases created in the last hour. Under high load (open cases > threshold) it reschedules itself every 15 minutes; under normal load every 60 minutes. A @TestVisible static helper builds the dynamic CRON expression.

Requirements

1. Implement Schedulable.
2. Constants: JOB_NAME, HIGH_LOAD_INTERVAL_MINUTES = 15, NORMAL_INTERVAL_MINUTES = 60, @TestVisible static final Integer CASE_THRESHOLD = 100.
3. @TestVisible static String buildCronExpression(Integer intervalMinutes):
   • DateTime nextRun = DateTime.now().addMinutes(intervalMinutes)
   • Return String.format('0 {0} {1} {2} {3} ? {4}', new List<Object>{ nextRun.minute(), nextRun.hour(), nextRun.day(), nextRun.month(), nextRun.year() })
4. execute():
   • COUNT Cases WHERE IsClosed = false AND CreatedDate >= :oneHourAgo.
   • Choose interval based on openCaseCount > CASE_THRESHOLD.
   • Guard abort + reschedule with !Test.isRunningTest().