mirror of https://github.com/python/cpython
412 lines
10 KiB
Python
412 lines
10 KiB
Python
# Tests for extended unpacking, starred expressions.
|
|
|
|
import doctest
|
|
import unittest
|
|
|
|
|
|
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 nested 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
|
|
|
|
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
|
|
|
|
>>> {0:1, **{0:2}, 0:3, 0:4}
|
|
{0: 4}
|
|
|
|
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
|
|
|
|
>>> {**{} for a in [1]}
|
|
Traceback (most recent call last):
|
|
...
|
|
SyntaxError: dict unpacking cannot be used in dict comprehension
|
|
|
|
# Pegen is better here.
|
|
# 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: test.test_unpack_ex.f() got multiple values for keyword argument 'x'
|
|
|
|
>>> f(**{'x': 3}, x=5, y=2)
|
|
Traceback (most recent call last):
|
|
...
|
|
TypeError: test.test_unpack_ex.f() got multiple values for keyword argument 'x'
|
|
|
|
>>> f(**{'x': 3}, **{'x': 5}, y=2)
|
|
Traceback (most recent call last):
|
|
...
|
|
TypeError: test.test_unpack_ex.f() got multiple values for keyword argument 'x'
|
|
|
|
>>> f(x=5, **{'x': 3}, **{'x': 2})
|
|
Traceback (most recent call last):
|
|
...
|
|
TypeError: test.test_unpack_ex.f() got multiple values for keyword argument 'x'
|
|
|
|
>>> f(**{1: 3}, **{1: 5})
|
|
Traceback (most recent call last):
|
|
...
|
|
TypeError: test.test_unpack_ex.f() got multiple values for keyword argument '1'
|
|
|
|
Unpacking non-sequence
|
|
|
|
>>> a, *b = 7
|
|
Traceback (most recent call last):
|
|
...
|
|
TypeError: cannot unpack non-iterable int object
|
|
|
|
Unpacking sequence too short
|
|
|
|
>>> a, *b, c, d, e = Seq()
|
|
Traceback (most recent call last):
|
|
...
|
|
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
|
|
|
|
>>> 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: multiple starred expressions in assignment
|
|
|
|
>>> [*b, *c] = range(10) # doctest:+ELLIPSIS
|
|
Traceback (most recent call last):
|
|
...
|
|
SyntaxError: multiple starred expressions in assignment
|
|
|
|
>>> a,*b,*c,*d = range(4) # doctest:+ELLIPSIS
|
|
Traceback (most recent call last):
|
|
...
|
|
SyntaxError: multiple 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't use starred expression here
|
|
|
|
>>> *1 # doctest:+ELLIPSIS
|
|
Traceback (most recent call last):
|
|
...
|
|
SyntaxError: can't use starred expression here
|
|
|
|
>>> x = *a # doctest:+ELLIPSIS
|
|
Traceback (most recent call last):
|
|
...
|
|
SyntaxError: can't use starred expression here
|
|
|
|
>>> (*x),y = 1, 2 # doctest:+ELLIPSIS
|
|
Traceback (most recent call last):
|
|
...
|
|
SyntaxError: cannot use starred expression here
|
|
|
|
>>> (((*x))),y = 1, 2 # doctest:+ELLIPSIS
|
|
Traceback (most recent call last):
|
|
...
|
|
SyntaxError: cannot use starred expression here
|
|
|
|
>>> z,(*x),y = 1, 2, 4 # doctest:+ELLIPSIS
|
|
Traceback (most recent call last):
|
|
...
|
|
SyntaxError: cannot use starred expression here
|
|
|
|
>>> z,(*x) = 1, 2 # doctest:+ELLIPSIS
|
|
Traceback (most recent call last):
|
|
...
|
|
SyntaxError: cannot use starred expression here
|
|
|
|
>>> ((*x),y) = 1, 2 # doctest:+ELLIPSIS
|
|
Traceback (most recent call last):
|
|
...
|
|
SyntaxError: cannot use starred expression here
|
|
|
|
Some size constraints (all fail.)
|
|
|
|
>>> s = ", ".join("a%d" % i for i in range(1<<8)) + ", *rest = range(1<<8 + 1)"
|
|
>>> compile(s, 'test', 'exec') # doctest:+ELLIPSIS
|
|
Traceback (most recent call last):
|
|
...
|
|
SyntaxError: too many expressions in star-unpacking assignment
|
|
|
|
>>> s = ", ".join("a%d" % i for i in range(1<<8 + 1)) + ", *rest = range(1<<8 + 2)"
|
|
>>> compile(s, 'test', 'exec') # doctest:+ELLIPSIS
|
|
Traceback (most recent call last):
|
|
...
|
|
SyntaxError: too many expressions in star-unpacking assignment
|
|
|
|
(there is an additional limit, on the number of expressions after the
|
|
'*rest', but it's 1<<24 and testing it takes too much memory.)
|
|
|
|
"""
|
|
|
|
__test__ = {'doctests' : doctests}
|
|
|
|
def load_tests(loader, tests, pattern):
|
|
tests.addTest(doctest.DocTestSuite())
|
|
return tests
|
|
|
|
|
|
if __name__ == "__main__":
|
|
unittest.main()
|