t/unit_core_setup.t uses it.
requires 'MRO::Compat';
test_requires 'Class::Data::Inheritable';
+test_requires 'Test::MockObject';
if ( ( exists $ENV{AGGREGATE_TESTS} && !$ENV{AGGREGATE_TESTS})
|| (!exists $ENV{AGGREGATE_TESTS} && !can_use('Test::Aggregate', '0.34_01'))) {