A way to run part unit tests N times, like the variable testing condition

It would be reassuring to be able to repeatedly randomise the question and run part unit tests, to see if they pass. The results could be presented as % of time the tests pass.

Start by locating the existing variable testing condition and the part unit-test runner described in the issue. Determine how repeated randomised runs could be requested and how pass results should be aggregated; done means the selected tests run N times and report the percentage of passing runs.

Written by the indexing model from the issue text.