def check_implicit_initialization(self, extract_randomness):
        """
        The PRNG in new threads should be implicitly initialized with
        system entropy, if seed() wasn't called.
        """
        results = self.extract_in_threads(4, extract_randomness, seed=0)

        # All threads gave a different, valid random sequence
        self.check_several_outputs(results, same_expected=False)

        The PRNG in new threads should be implicitly initialized with
        system entropy, if seed() wasn't called.
        
numba/tests/test_random.py