unit_test_performance.py 文件源码

def test_slice_vs_startswith(self):
    setup = '''x = 'a' * 100\n'''
    a = timeit(
        '''x[:2] == "  "\n''',
        setup=setup,
        number=100000)
    b = timeit(
        '''x.startswith("  ")\n''',
        setup=setup,
        number=100000)
    c = timeit(
        '''x[0] == " " and x[1] == " "\n''',
        setup=setup,
        number=100000)
    #print "\na %s, b %s, c %s | %s %s" % (a, b, c, c, a/c)
    # Calling a function or member is significantly slower than direct access.
    self.assertGreater(b, a * 2.0)  # b is much slower.
    self.assertGreater(b, c * 2.0)  # b is much slower.
    self.assertGreater(a, c * 0.7)  # a and c are similar.
    self.assertGreater(c, a * 0.7)  # a and c are similar.