salesforce Schedule Jobs用法

global class deleteANSMessageJob implements Schedulable {
//Execute method
global void execute (SchedulableContext SC) {
DateTime recordDate = DateTime.now().date();
//recordDate = recordDate.addMonths(-2);
List<ANS_Message_Repository__c> messages = [select Id from ANS_Message_Repository__c where LastModifiedDate <:recordDate ];
integer count = messages.size();
delete messages ;
system.debug('delete count: '+count);
}
}

@isTest
private class deleteANSMessageJobTest{
static testMethod void deleteANSMessageJobTest(){
Test.startTest();
//Schedule the test job
String CRON_EXP = '0 1 * * * ? *';//per 1min
String jobId = System.schedule('deleteANSMessageJob',CRON_EXP,new deleteANSMessageJob());
//get current total
DateTime recordDate = DateTime.now().date();
//recordDate = recordDate.addMonths(-2);
List<ANS_Message_Repository__c> messages = [select Id from ANS_Message_Repository__c where LastModifiedDate <:recordDate ];
integer total = messages.size();
System.assertEquals(0,total);
Test.stopTest();
}
}

提示：在testclass里做的所有操作（DELETE,UPDATE,CREATE）都不会影响原始数据

cron在线表达式生成：http://cron.qqe2.com/

参考资料：

https://developer.salesforce.com/docs/atlas.en-us.apexcode.meta/apexcode/apex_scheduler.htm

https://trailhead.salesforce.com/en/modules/asynchronous_apex/units/async_apex_scheduled