Spring scheduled task cron expression validation - spring-boot

Question

I'm writing a scheduled task that need to run every 1st Saturday of each month.
I came up with this:
#Scheduled(cron = "0 0 23 1-7 * SAT")
// Runs on 1st Saturday of each month at 23:00
public void CleanUpScheduledTask() {
}
How did I come uo with this:
0 0 23 means at 11:00 PM everyday
1-7 * means between 1-7 every month
SAT Saturdays
How do you suggest to make sure that the above expression is valid? how I test such functionalities?
Thanks for the help.

Answer 1

1. Building Cron Expression
Using the Spring cron job expression
#Scheduled(cron = "[Seconds] [Minutes] [Hours] [Day of month] [Month] [Day of week] [Year]")
NB year field is optional
# used to specify day of the week and week the task should start.
eg first Saturday of every month(7#1)
? represents no specific value and can be used in either the day of month or day of week field
* represents all values
hence cron expression becomes
#Scheduled(cron = "0 0 23 ? * 7#1")
2. Testing Cron Job
use Awaitility dependency
<dependency>
<groupId>org.awaitility</groupId>
<artifactId>awaitility</artifactId>
<scope>test</scope>
</dependency>
-using Spring Integration testing
#SpringJUnitConfig(CleanScheduler.class)
public class CleanSchedulerUnitTest {
#Autowired
private CleanScheduler cleanScheduler;
#Test
void cleanUpScheduledTaskShouldReturnSuccess() {
//Act
cleanScheduler.cleanUpScheduledTask();
//Assertions
}
}

Answer 2

You can use an online Cron generator like https://www.freeformatter.com/cron-expression-generator-quartz.html to generate cron expressions or to describe what you posted.
0 0 0,23 ? * 7#1 * should be described and run At second:00, at minute:00, at 00 am and 23pm, on the 1st Saturday of the month, every month.