Using RunException for testing mooseWarning

[WilkAndy]

Is it OK to use a RunException test to check that this type of warning is issued by MOOSE:

  if (_s_lr <= _s_l_min)
    mooseWarning("S_lr should usually be greater than S_l_min");

[loganharbour]

Seems reasonable. I would add

cli_args = '--error'

at the minimum so it's treated as an error in testing.

[WilkAndy]

Thanks @loganharbour