Use Test Post option for this.
Find the Test Post option in the campaign's log pop-up:
Test Post option is also available in the campaign's editor in the Automation section:
As soon as you run Test Post option, you will see a "Test post is processing.." message. It may take several seconds to make a post. As soon as test post is done a new record will appear in the campaign's log.
Note: Test Post option doesn't affect campaign's posting automation settings.