The custom testing library supports multiple GIVEN, WHEN and THEN blocks when using test scenarios. However, there seems to be a bug when making multiple blocks of the same type in scenario outlines. The code will compile without errors, but running the test executable will result with the following exceptions.
For multiple WHEN blocks we get:

Suite: caf.scheduler
  unhandled exception: abort test run
    loc: unknown
    msg: failed to select  the root block for the scenario

For multiple THEN blocks we get:

  unhandled exception: abort test run
    loc: /home/samir/projects/actor-framework/libcaf_core/caf/scheduler.test.cpp:65
    msg: too many THEN blocks in a WHEN block