Method test_unpack_iter

Lib/test/test_iter.py:938–988

(self)

    # Test iterators on RHS of unpacking assignments.
    def test_unpack_iter(self):
        a, b = 1, 2
        self.assertEqual((a, b), (1, 2))

        a, b, c = IteratingSequenceClass(3)
        self.assertEqual((a, b, c), (0, 1, 2))

        try:    # too many values
            a, b = IteratingSequenceClass(3)
        except ValueError:
            pass
        else:
            self.fail("should have raised ValueError")

        try:    # not enough values
            a, b, c = IteratingSequenceClass(2)
        except ValueError:
            pass
        else:
            self.fail("should have raised ValueError")

        try:    # not iterable
            a, b, c = len
        except TypeError:
            pass
        else:
            self.fail("should have raised TypeError")

        a, b, c = {1: 42, 2: 42, 3: 42}.values()
        self.assertEqual((a, b, c), (42, 42, 42))

        f = open(TESTFN, "w", encoding="utf-8")
        lines = ("a\n", "bb\n", "ccc\n")
        try:
            for line in lines:
                f.write(line)
        finally:
            f.close()
        f = open(TESTFN, "r", encoding="utf-8")
        try:
            a, b, c = f
            self.assertEqual((a, b, c), lines)
        finally:
            f.close()
            try:
                unlink(TESTFN)
            except OSError:
                pass

        (a, b), (c,) = IteratingSequenceClass(2), {42: 24}
        self.assertEqual((a, b, c), (0, 1, 42))


    @cpython_only