diff options
Diffstat (limited to 'Lib/test/test_unpack_ex.py')
| -rw-r--r-- | Lib/test/test_unpack_ex.py | 192 |
1 files changed, 188 insertions, 4 deletions
diff --git a/Lib/test/test_unpack_ex.py b/Lib/test/test_unpack_ex.py index ae2dcbd..01f57b9 100644 --- a/Lib/test/test_unpack_ex.py +++ b/Lib/test/test_unpack_ex.py @@ -71,8 +71,185 @@ Multiple targets >>> a == 0 and b == [1, 2, 3] and c == 4 and d == [0, 1, 2, 3] and e == 4 True +Assignment unpacking + + >>> a, b, *c = range(5) + >>> a, b, c + (0, 1, [2, 3, 4]) + >>> *a, b, c = a, b, *c + >>> a, b, c + ([0, 1, 2], 3, 4) + +Set display element unpacking + + >>> a = [1, 2, 3] + >>> sorted({1, *a, 0, 4}) + [0, 1, 2, 3, 4] + + >>> {1, *1, 0, 4} + Traceback (most recent call last): + ... + TypeError: 'int' object is not iterable + +Dict display element unpacking + + >>> kwds = {'z': 0, 'w': 12} + >>> sorted({'x': 1, 'y': 2, **kwds}.items()) + [('w', 12), ('x', 1), ('y', 2), ('z', 0)] + + >>> sorted({**{'x': 1}, 'y': 2, **{'z': 3}}.items()) + [('x', 1), ('y', 2), ('z', 3)] + + >>> sorted({**{'x': 1}, 'y': 2, **{'x': 3}}.items()) + [('x', 3), ('y', 2)] + + >>> sorted({**{'x': 1}, **{'x': 3}, 'x': 4}.items()) + [('x', 4)] + + >>> {**{}} + {} + + >>> a = {} + >>> {**a}[0] = 1 + >>> a + {} + + >>> {**1} + Traceback (most recent call last): + ... + TypeError: 'int' object is not a mapping + + >>> {**[]} + Traceback (most recent call last): + ... + TypeError: 'list' object is not a mapping + + >>> len(eval("{" + ", ".join("**{{{}: {}}}".format(i, i) + ... for i in range(1000)) + "}")) + 1000 + +List comprehension element unpacking + + >>> a, b, c = [0, 1, 2], 3, 4 + >>> [*a, b, c] + [0, 1, 2, 3, 4] + + >>> l = [a, (3, 4), {5}, {6: None}, (i for i in range(7, 10))] + >>> [*item for item in l] + Traceback (most recent call last): + ... + SyntaxError: iterable unpacking cannot be used in comprehension + + >>> [*[0, 1] for i in range(10)] + Traceback (most recent call last): + ... + SyntaxError: iterable unpacking cannot be used in comprehension + + >>> [*'a' for i in range(10)] + Traceback (most recent call last): + ... + SyntaxError: iterable unpacking cannot be used in comprehension + + >>> [*[] for i in range(10)] + Traceback (most recent call last): + ... + SyntaxError: iterable unpacking cannot be used in comprehension + +Generator expression in function arguments + + >>> list(*x for x in (range(5) for i in range(3))) + Traceback (most recent call last): + ... + list(*x for x in (range(5) for i in range(3))) + ^ + SyntaxError: invalid syntax + + >>> dict(**x for x in [{1:2}]) + Traceback (most recent call last): + ... + dict(**x for x in [{1:2}]) + ^ + SyntaxError: invalid syntax + +Iterable argument unpacking + + >>> print(*[1], *[2], 3) + 1 2 3 + +Make sure that they don't corrupt the passed-in dicts. + + >>> def f(x, y): + ... print(x, y) + ... + >>> original_dict = {'x': 1} + >>> f(**original_dict, y=2) + 1 2 + >>> original_dict + {'x': 1} + Now for some failures +Make sure the raised errors are right for keyword argument unpackings + + >>> from collections.abc import MutableMapping + >>> class CrazyDict(MutableMapping): + ... def __init__(self): + ... self.d = {} + ... + ... def __iter__(self): + ... for x in self.d.__iter__(): + ... if x == 'c': + ... self.d['z'] = 10 + ... yield x + ... + ... def __getitem__(self, k): + ... return self.d[k] + ... + ... def __len__(self): + ... return len(self.d) + ... + ... def __setitem__(self, k, v): + ... self.d[k] = v + ... + ... def __delitem__(self, k): + ... del self.d[k] + ... + >>> d = CrazyDict() + >>> d.d = {chr(ord('a') + x): x for x in range(5)} + >>> e = {**d} + Traceback (most recent call last): + ... + RuntimeError: dictionary changed size during iteration + + >>> d.d = {chr(ord('a') + x): x for x in range(5)} + >>> def f(**kwargs): print(kwargs) + >>> f(**d) + Traceback (most recent call last): + ... + RuntimeError: dictionary changed size during iteration + +Overridden parameters + + >>> f(x=5, **{'x': 3}, y=2) + Traceback (most recent call last): + ... + TypeError: f() got multiple values for keyword argument 'x' + + >>> f(**{'x': 3}, x=5, y=2) + Traceback (most recent call last): + ... + TypeError: f() got multiple values for keyword argument 'x' + + >>> f(**{'x': 3}, **{'x': 5}, y=2) + Traceback (most recent call last): + ... + TypeError: f() got multiple values for keyword argument 'x' + + >>> f(**{1: 3}, **{1: 5}) + Traceback (most recent call last): + ... + TypeError: f() keywords must be strings + Unpacking non-sequence >>> a, *b = 7 @@ -85,7 +262,14 @@ Unpacking sequence too short >>> a, *b, c, d, e = Seq() Traceback (most recent call last): ... - ValueError: need more than 3 values to unpack + ValueError: not enough values to unpack (expected at least 4, got 3) + +Unpacking sequence too short and target appears last + + >>> a, b, c, d, *e = Seq() + Traceback (most recent call last): + ... + ValueError: not enough values to unpack (expected at least 4, got 3) Unpacking a sequence where the test for too long raises a different kind of error @@ -131,17 +315,17 @@ Now some general starred expressions (all fail). >>> *a # doctest:+ELLIPSIS Traceback (most recent call last): ... - SyntaxError: can use starred expression only as assignment target + SyntaxError: can't use starred expression here >>> *1 # doctest:+ELLIPSIS Traceback (most recent call last): ... - SyntaxError: can use starred expression only as assignment target + SyntaxError: can't use starred expression here >>> x = *a # doctest:+ELLIPSIS Traceback (most recent call last): ... - SyntaxError: can use starred expression only as assignment target + SyntaxError: can't use starred expression here Some size constraints (all fail.) |