Method test_writelines

Lib/test/test_iter.py:885–934

(self)

    # Test iterators with file.writelines().
    def test_writelines(self):
        f = open(TESTFN, "w", encoding="utf-8")

        try:
            self.assertRaises(TypeError, f.writelines, None)
            self.assertRaises(TypeError, f.writelines, 42)

            f.writelines(["1\n", "2\n"])
            f.writelines(("3\n", "4\n"))
            f.writelines({'5\n': None})
            f.writelines({})

            # Try a big chunk too.
            class Iterator:
                def __init__(self, start, finish):
                    self.start = start
                    self.finish = finish
                    self.i = self.start

                def __next__(self):
                    if self.i >= self.finish:
                        raise StopIteration
                    result = str(self.i) + '\n'
                    self.i += 1
                    return result

                def __iter__(self):
                    return self

            class Whatever:
                def __init__(self, start, finish):
                    self.start = start
                    self.finish = finish

                def __iter__(self):
                    return Iterator(self.start, self.finish)

            f.writelines(Whatever(6, 6+2000))
            f.close()

            f = open(TESTFN, encoding="utf-8")
            expected = [str(i) + "\n" for i in range(1, 2006)]
            self.assertEqual(list(f), expected)

        finally:
            f.close()
            try:
                unlink(TESTFN)
            except OSError:
                pass


    # Test iterators on RHS of unpacking assignments.