How to inspect outgoing email content during a SimpleTest? I see that SimpleTest has a few built in mail functions to check for send success etc, but how can I send a message, assert its content and then click a link within that content during a test?

What is the standard or most common way to test unsubscribe, or account verification links in emails with SimpleTest?
Simpletest automatically captures sent mails during a test and allows you to fetch them using $this->drupalGetMails() in the test class.

I did something like this recently in tests I wrote for the Simplenews project, to test subscription confirmation here.