def file_hash(self, filename):
    return hashlib.sha256(open(filename).read()).hexdigest()
L{_iterateTests} returns tests in left-to-right, depth-first order.
dataset/ETHPy150Open jansel/opentuner/opentuner/measurement/interface.py/MeasurementInterface.file_hash--crossover with--dataset/ETHPy150Open nlloyd/SubliminalCollaborator/libs/twisted/trial/test/test_tests.py/IterateTestsMixin.test_iterateIsLeftToRightDepthFirst