| # Tests for extended unpacking, starred expressions. |
| |
| doctests = """ |
| |
| Unpack tuple |
| |
| >>> t = (1, 2, 3) |
| >>> a, *b, c = t |
| >>> a == 1 and b == [2] and c == 3 |
| True |
| |
| Unpack list |
| |
| >>> l = [4, 5, 6] |
| >>> a, *b = l |
| >>> a == 4 and b == [5, 6] |
| True |
| |
| Unpack implied tuple |
| |
| >>> *a, = 7, 8, 9 |
| >>> a == [7, 8, 9] |
| True |
| |
| Unpack string... fun! |
| |
| >>> a, *b = 'one' |
| >>> a == 'o' and b == ['n', 'e'] |
| True |
| |
| Unpack long sequence |
| |
| >>> a, b, c, *d, e, f, g = range(10) |
| >>> (a, b, c, d, e, f, g) == (0, 1, 2, [3, 4, 5, 6], 7, 8, 9) |
| True |
| |
| Unpack short sequence |
| |
| >>> a, *b, c = (1, 2) |
| >>> a == 1 and c == 2 and b == [] |
| True |
| |
| Unpack generic sequence |
| |
| >>> class Seq: |
| ... def __getitem__(self, i): |
| ... if i >= 0 and i < 3: return i |
| ... raise IndexError |
| ... |
| >>> a, *b = Seq() |
| >>> a == 0 and b == [1, 2] |
| True |
| |
| Unpack in for statement |
| |
| >>> for a, *b, c in [(1,2,3), (4,5,6,7)]: |
| ... print(a, b, c) |
| ... |
| 1 [2] 3 |
| 4 [5, 6] 7 |
| |
| Unpack in list |
| |
| >>> [a, *b, c] = range(5) |
| >>> a == 0 and b == [1, 2, 3] and c == 4 |
| True |
| |
| Multiple targets |
| |
| >>> a, *b, c = *d, e = range(5) |
| >>> a == 0 and b == [1, 2, 3] and c == 4 and d == [0, 1, 2, 3] and e == 4 |
| True |
| |
| Now for some failures |
| |
| Unpacking non-sequence |
| |
| >>> a, *b = 7 |
| Traceback (most recent call last): |
| ... |
| TypeError: 'int' object is not iterable |
| |
| Unpacking sequence too short |
| |
| >>> a, *b, c, d, e = Seq() |
| Traceback (most recent call last): |
| ... |
| ValueError: need more than 3 values to unpack |
| |
| Unpacking a sequence where the test for too long raises a different kind of |
| error |
| |
| >>> class BozoError(Exception): |
| ... pass |
| ... |
| >>> class BadSeq: |
| ... def __getitem__(self, i): |
| ... if i >= 0 and i < 3: |
| ... return i |
| ... elif i == 3: |
| ... raise BozoError |
| ... else: |
| ... raise IndexError |
| ... |
| |
| Trigger code while not expecting an IndexError (unpack sequence too long, wrong |
| error) |
| |
| >>> a, *b, c, d, e = BadSeq() |
| Traceback (most recent call last): |
| ... |
| test.test_unpack_ex.BozoError |
| |
| Now some general starred expressions (all fail). |
| |
| >>> a, *b, c, *d, e = range(10) # doctest:+ELLIPSIS |
| Traceback (most recent call last): |
| ... |
| SyntaxError: two starred expressions in assignment (...) |
| |
| >>> [*b, *c] = range(10) # doctest:+ELLIPSIS |
| Traceback (most recent call last): |
| ... |
| SyntaxError: two starred expressions in assignment (...) |
| |
| >>> *a = range(10) # doctest:+ELLIPSIS |
| Traceback (most recent call last): |
| ... |
| SyntaxError: starred assignment target must be in a list or tuple (...) |
| |
| >>> *a # doctest:+ELLIPSIS |
| Traceback (most recent call last): |
| ... |
| SyntaxError: can use starred expression only as assignment target (...) |
| |
| >>> *1 # doctest:+ELLIPSIS |
| Traceback (most recent call last): |
| ... |
| SyntaxError: can use starred expression only as assignment target (...) |
| |
| >>> x = *a # doctest:+ELLIPSIS |
| Traceback (most recent call last): |
| ... |
| SyntaxError: can use starred expression only as assignment target (...) |
| |
| """ |
| |
| __test__ = {'doctests' : doctests} |
| |
| def test_main(verbose=False): |
| import sys |
| from test import test_support |
| from test import test_unpack_ex |
| test_support.run_doctest(test_unpack_ex, verbose) |
| |
| if __name__ == "__main__": |
| test_main(verbose=True) |