test-data/unit/check-lists.test

-- Nested list assignment
-- -----------------------------

[case testNestedListAssignment]
from typing import List
a1, b1, c1 = None, None, None # type: (A, B, C)
a2, b2, c2 = None, None, None # type: (A, B, C)

a1, [b1, c1] = a2, [b2, c2]
a1, [a1, [b1, c1]] = a2, [a2, [b2, c2]]
a1, [a1, [a1, b1]] = a1, [a1, [a1, c1]]  # E: Incompatible types in assignment (expression has type "C", variable has type "B")

class A: pass
class B: pass
class C: pass
[builtins fixtures/list.pyi]
[out]

[case testNestedListAssignmentToTuple]
from typing import List
a, b, c = None, None, None # type: (A, B, C)

a, b = [a, b]
a, b = [a]  # E: Need more than 1 value to unpack (2 expected)
a, b = [a, b, c]  # E: Too many values to unpack (2 expected, 3 provided)

class A: pass
class B: pass
class C: pass
[builtins fixtures/list.pyi]
[out]

[case testListAssignmentFromTuple]
from typing import List
a, b, c = None, None, None # type: (A, B, C)
t = a, b

[a, b], c = t, c
[a, c], c = t, c  # E: Incompatible types in assignment (expression has type "B", variable has type "C")
[a, a, a], c = t, c  # E: Need more than 2 values to unpack (3 expected)
[a], c = t, c  # E: Too many values to unpack (1 expected, 2 provided)

class A: pass
class B: pass
class C: pass
[builtins fixtures/list.pyi]
[out]

[case testListAssignmentUnequalAmountToUnpack]
from typing import List
a, b, c = None, None, None # type: (A, B, C)

def f() -> None: # needed because test parser tries to parse [a, b] as section header
    [a, b] = [a, b]
    [a, b] = [a]  # E: Need more than 1 value to unpack (2 expected)
    [a, b] = [a, b, c]  # E: Too many values to unpack (2 expected, 3 provided)

class A: pass
class B: pass
class C: pass
[builtins fixtures/list.pyi]
[out]

[case testListWithStarExpr]
(x, *a) = [1, 2, 3]
a = [1, *[2, 3]]
reveal_type(a)  # E: Revealed type is 'builtins.list[builtins.int]'
b = [0, *a]
reveal_type(b)  # E: Revealed type is 'builtins.list[builtins.int*]'
c = [*a, 0]
reveal_type(c)  # E: Revealed type is 'builtins.list[builtins.int*]'
[builtins fixtures/list.pyi]