ert--running-tests

ert--running-tests is a variable defined in `ert.el'.
Its value is

nil

Documentation:
List of tests that are currently in execution.

This list is empty while no test is running, has one element
while a test is running, two elements while a test run from
inside a test is running, etc. The list is in order of nesting,
innermost test first.

The elements are of type `ert-test'.