'Invokes a test on a value the same way the compiler does it.
.. versionadded:: 2.7'

def call_test(self, name, value, args=None, kwargs=None):

    func = self.tests.get(name)
    if (func is None):
        fail_for_missing_callable('no    test    named    %r', name)
    return func(value, *(args or ()), **(kwargs or {}))
