A filter is a callable that accepts an iterable of tests and a dictionary of values (e.g mozinfo.info) and returns an iterable of tests. Note filtering can mean modifying tests in addition to removing them. For example, this implements a "timeout-if" tag in the manifest:
from manifestparser import expression
import mozinfo
def timeout_if(tests, values):
for test in tests:
if 'timeout-if' in test:
timeout, condition = test['timeout-if'].split(',', 1)
if expression.parse(condition, **values):
test['timeout'] = timeout
yield test
tests = mp.active_tests(filters=[timeout_if], **mozinfo.info)
