test_tempfile.py 文件源码

def test_truncate_with_size_parameter(self):
        # A SpooledTemporaryFile can be truncated to zero size
        f = tempfile.SpooledTemporaryFile(max_size=10)
        f.write(b'abcdefg\n')
        f.seek(0)
        f.truncate()
        self.assertFalse(f._rolled)
        self.assertEqual(f._file.getvalue(), b'')
        # A SpooledTemporaryFile can be truncated to a specific size
        f = tempfile.SpooledTemporaryFile(max_size=10)
        f.write(b'abcdefg\n')
        f.truncate(4)
        self.assertFalse(f._rolled)
        self.assertEqual(f._file.getvalue(), b'abcd')
        # A SpooledTemporaryFile rolls over if truncated to large size
        f = tempfile.SpooledTemporaryFile(max_size=10)
        f.write(b'abcdefg\n')
        f.truncate(20)
        self.assertTrue(f._rolled)
        if has_stat:
            self.assertEqual(os.fstat(f.fileno()).st_size, 20)