Last week micro-iterations landed in Mozmill Endurance Tests. These allow tests to accumulate resources during an iteration. This was previously achieved by leaving the state of the test snippet in a different state to how it started, allowing the iterations themselves to accumulate. The problem with this is that these accumulating tests have a very different pattern compared to other tests that clean up before ending the iteration.
To solve this we decided to add a micro-iteration parameter and to use it to loop within an iteration. An example use for this is the new tab tests. Now, if you specify 5 iterations and 10 micro-iterations then these tests will open 10 new tabs, close them, and repeat that 5 times.
The endurance tests documentation has been updated with details on writing and running tests with micro-iterations.