Method check

Lib/test/test_io.py:765–768

(f)

        a = array.array('i', range(10))
        n = len(a.tobytes())
        def check(f):
            with f:
                self.assertEqual(f.write(a), n)
                f.writelines((a,))
        check(self.BytesIO())
        check(self.FileIO(os_helper.TESTFN, "w"))
        check(self.BufferedWriter(self.MockRawIO()))