This buildstep is similar to ShellCommand, except that it runs the log content through a subunit filter to extract test and failure counts.
from buildbot.steps.subunit import SubunitShellCommand
f.addStep(SubunitShellCommand(command="make test", failureOnNoTests=False))
This runs make test and filters it through subunit. The 'tests' and
'test failed' progress metrics will now accumulate test data from the test run.
If failureOnNoTests is True, this step will fail if no test is run. By
default failureOnNoTests is False.