pythoneval.test

-- Test cases for type checking mypy programs using full stubs and running
-- using CPython.
--
-- These are mostly regression tests -- no attempt is made to make these
-- complete.


[case testHello]
import typing
print('hello, world')
[out]
hello, world

[case testMiscStdlibFeatures]
# Various legacy tests merged together to speed up test runtimes.

def f(x: object) -> None: pass

# testReversed
from typing import Reversible
class R(Reversible):
    def __iter__(self): return iter('oof')
    def __reversed__(self): return iter('foo')
f(list(reversed(range(5))))
f(list(reversed([1,2,3])))
f(list(reversed('abc')))
f(list(reversed(R())))

# testIntAndFloatConversion
from typing import SupportsInt, SupportsFloat
class A(SupportsInt):
    def __int__(self): return 5
class B(SupportsFloat):
    def __float__(self): return 1.2
f(int(1))
f(int(6.2))
f(int('3'))
f(int(b'4'))
f(int(A()))
f(float(-9))
f(float(B()))

# testAbs
from typing import SupportsAbs
class Ab(SupportsAbs[float]):
    def __abs__(self) -> float: return 5.5

f(abs(-1))
f(abs(-1.2))
f(abs(Ab()))

# testRound
from typing import SupportsRound
class Ro(SupportsRound):
    def __round__(self, ndigits=0): return 'x%d' % ndigits
f(round(1.6))
f(round(Ro()))
f(round(Ro(), 2))

# testCallMethodViaTypeObject
list.__add__([1, 2], [3, 4])

# testInheritedClassAttribute
import typing
class AA:
    x = 1
    def f(self: typing.Optional["AA"]) -> None: pass
class BB(AA):
    pass
BB.f(None)
f(BB.x)

# testSpecialAttributes
class Doc:
    """A docstring!"""
f(Doc().__doc__)
f(Doc().__class__)

# testFunctionAttributes
f(ord.__class__)
f(type(ord.__doc__ or '' + ''))
f(ord.__name__)
f(ord.__module__)

# testModuleAttributes
import math
f(type(__spec__))
f(math.__name__)
f(math.__spec__.name)
f(type(math.__dict__))
f(type(math.__doc__ or ''))
f(type(math.__spec__).__name__)
f(math.__class__)

[case testAbs2]
n: int
f: float
n = abs(1)
abs(1) + 'x'  # Error
f = abs(1.1)
abs(1.1) + 'x'  # Error
[out]
_program.py:4: error: Unsupported operand types for + ("int" and "str")
_program.py:6: error: Unsupported operand types for + ("float" and "str")

[case testTypeAttributes]
import typing
print(str.__class__)
print(type(str.__doc__))
print(str.__name__)
print(str.__module__)
print(str.__dict__ is not None)
[out]
<class 'type'>
<class 'str'>
str
builtins
True

[case testBoolCompatibilityWithInt]
import typing
x = 0
x = True
print(bool('x'))
print(bool(''))
[out]
True
False

[case testCannotExtendBoolUnlessIgnored]
class A(bool): pass
class B(bool): pass  # type: ignore
[out]
_program.py:1: error: Cannot inherit from final class "bool"

[case testCallBuiltinTypeObjectsWithoutArguments]
import typing
print(int())
print(repr(str()))
print(repr(bytes()))
print(float())
print(bool())
[out]
0
''
b''
0.0
False

[case testIntegerDivision]
import typing
x = 1 / 2
x = 1.5
[out]

[case testIntMethods]
import typing
print(int.from_bytes(b'ab', 'big'))
n = 0
print(n.from_bytes(b'ac', 'big'))
print(n.from_bytes([2, 3], 'big'))
print(n.to_bytes(2, 'big'))
[out]
24930
24931
515
b'\x00\x00'

[case testFloatMethods]
import typing
print(1.5.as_integer_ratio())
print(1.5.hex())
print(2.0.is_integer())
print(float.fromhex('0x1.8'))
[out]
(3, 2)
0x1.8000000000000p+0
True
1.5

[case testDictFromkeys]
import typing
d = dict.fromkeys('foo')
d['x'] = 2
d2 = dict.fromkeys([1, 2], b'')
d2[2] = b'foo'
[out]

[case testIsinstanceWithTuple]
from typing import cast, Any
x = cast(Any, (1, 'x'))
if isinstance(x, tuple):
    print(x[0], x[1])
[out]
1 x

[case testAnyStr]
from typing import AnyStr
def f(x: AnyStr) -> AnyStr:
    if isinstance(x, str):
        return 'foo'
    else:
        return b'zar'
print(f(''))
print(f(b''))
[out]
foo
b'zar'

[case testNameNotImportedFromTyping]
import typing
cast(int, 2)
[out]
_program.py:2: error: Name "cast" is not defined
_program.py:2: note: Did you forget to import it from "typing"? (Suggestion: "from typing import cast")

[case testBinaryIOType]
from typing import BinaryIO
def f(f: BinaryIO) -> None:
    f.write(b'foo')
    f.write(bytearray(b'foo'))
[out]

[case testIOTypes]
from typing import IO
import sys
def txt(f: IO[str]) -> None:
    f.write('foo')
    f.write(b'foo')
def bin(f: IO[bytes]) -> None:
    f.write(b'foo')
    f.write(bytearray(b'foo'))
txt(sys.stdout)
bin(sys.stdout)
[out]
_program.py:5: error: Argument 1 to "write" of "IO" has incompatible type "bytes"; expected "str"
_program.py:10: error: Argument 1 to "bin" has incompatible type "Union[TextIO, Any]"; expected "IO[bytes]"

[case testBuiltinOpen]
f = open('x')
f.write('x')
f.write(b'x')
f.foobar()
[out]
_program.py:3: error: Argument 1 to "write" of "_TextIOBase" has incompatible type "bytes"; expected "str"
_program.py:4: error: "TextIOWrapper[_WrappedBuffer]" has no attribute "foobar"

[case testOpenReturnTypeInference]
reveal_type(open('x'))
reveal_type(open('x', 'r'))
reveal_type(open('x', 'rb'))
mode = 'rb'
reveal_type(open('x', mode))
[out]
_program.py:1: note: Revealed type is "_io.TextIOWrapper[_io._WrappedBuffer]"
_program.py:2: note: Revealed type is "_io.TextIOWrapper[_io._WrappedBuffer]"
_program.py:3: note: Revealed type is "_io.BufferedReader"
_program.py:5: note: Revealed type is "typing.IO[Any]"

[case testOpenReturnTypeInferenceSpecialCases]
reveal_type(open(mode='rb', file='x'))
reveal_type(open(file='x', mode='rb'))
mode = 'rb'
reveal_type(open(mode=mode, file='r'))
[out]
_testOpenReturnTypeInferenceSpecialCases.py:1: note: Revealed type is "_io.BufferedReader"
_testOpenReturnTypeInferenceSpecialCases.py:2: note: Revealed type is "_io.BufferedReader"
_testOpenReturnTypeInferenceSpecialCases.py:4: note: Revealed type is "typing.IO[Any]"

[case testPathOpenReturnTypeInference]
from pathlib import Path
p = Path("x")
reveal_type(p.open())
reveal_type(p.open('r'))
reveal_type(p.open('rb'))
mode = 'rb'
reveal_type(p.open(mode))
[out]
_program.py:3: note: Revealed type is "_io.TextIOWrapper[_io._WrappedBuffer]"
_program.py:4: note: Revealed type is "_io.TextIOWrapper[_io._WrappedBuffer]"
_program.py:5: note: Revealed type is "_io.BufferedReader"
_program.py:7: note: Revealed type is "typing.IO[Any]"

[case testPathOpenReturnTypeInferenceSpecialCases]
from pathlib import Path
p = Path("x")
reveal_type(p.open(mode='r', errors='replace'))
reveal_type(p.open(errors='replace', mode='r'))
mode = 'r'
reveal_type(p.open(mode=mode, errors='replace'))
[out]
_program.py:3: note: Revealed type is "_io.TextIOWrapper[_io._WrappedBuffer]"
_program.py:4: note: Revealed type is "_io.TextIOWrapper[_io._WrappedBuffer]"
_program.py:6: note: Revealed type is "typing.IO[Any]"

[case testGenericPatterns]
from typing import Pattern
import re
p: Pattern[str]
p = re.compile('foo*')
b: Pattern[bytes]
b = re.compile(b'foo*')
m = p.match('fooo')
assert m
print(m.group(0))
[out]
fooo

[case testGenericMatch]
from typing import Match, Optional
import re
def f(m: Optional[Match[bytes]]) -> None:
    assert m
    print(m.group(0))
f(re.match(b'x*', b'xxy'))
[out]
b'xx'

[case testIntFloatDucktyping]
x: float
x = 2.2
x = 2
def f(x: float) -> None: pass
f(1.1)
f(1)
[out]

[case testsFloatOperations]
import typing
print(1.5 + 1.5)
print(1.5 + 1)
[out]
3.0
2.5

[case testMathFunctionWithIntArgument]
import typing
import math
math.sin(2)
math.sin(2.2)

[case testAbsReturnType]
f: float
n: int
n = abs(2)
f = abs(2.2)
abs(2.2) + 'x'
[out]
_program.py:5: error: Unsupported operand types for + ("float" and "str")

[case testROperatorMethods]
b: bytes
s: str
if int():
    s = b'foo' * 5 # Error
if int():
    b = 5 * b'foo'
if int():
    b = b'foo' * 5
if int():
    s = 5 * 'foo'
if int():
    s = 'foo' * 5
[out]
_program.py:4: error: Incompatible types in assignment (expression has type "bytes", variable has type "str")

[case testROperatorMethods2]
import typing
print(2 / 0.5)
print(' ', 2 * [3, 4])
[out]
4.0
  [3, 4, 3, 4]

[case testNotImplemented]
import typing
class A:
    def __add__(self, x: int) -> int:
        if isinstance(x, int):
            return x + 1
        return NotImplemented
class B:
    def __radd__(self, x: A) -> str:
        return 'x'
print(A() + 1)
print(A() + B())
[out]
2
x

[case testMappingMethods]
# Regression test
from typing import Mapping
x = {'x': 'y'} # type: Mapping[str, str]
print('x' in x)
print('y' in x)
[out]
True
False

[case testOverlappingOperatorMethods]
class X: pass
class A:
    def __add__(self, x: object) -> int:
        if isinstance(x, X):
            return 1
        return NotImplemented
class B:
    def __radd__(self, x: A) -> str: return 'x'
class C(X, B): pass
b: B
b = C()
print(A() + b)
[out]
_program.py:8: error: Signatures of "__radd__" of "B" and "__add__" of "A" are unsafely overlapping

[case testBytesAndBytearrayComparisons]
import typing
print(b'ab' < bytearray(b'b'))
print(bytearray(b'ab') < b'a')
[out]
True
False

[case testBytesAndBytearrayComparisons2]
import typing
'' < b''
b'' < ''
'' < bytearray()
bytearray() < ''
[out]
_program.py:2: error: Unsupported operand types for < ("str" and "bytes")
_program.py:3: error: Unsupported operand types for < ("bytes" and "str")
_program.py:4: error: Unsupported operand types for < ("str" and "bytearray")
_program.py:5: error: Unsupported operand types for < ("bytearray" and "str")

[case testInplaceOperatorMethod]
import typing
a = [1]
print('', a.__iadd__([2]))
print('', a)
[out]
 [1, 2]
 [1, 2]

[case testListInplaceAdd]
import typing
a = [1]
a += iter([2, 3])
print(tuple(a))
[out]
(1, 2, 3)

[case testInferHeterogeneousListOfIterables]
from typing import Sequence
s = ['x', 'y'] # type: Sequence[str]
a = [['x', 'x'], 'fo', s, iter('foo'), {'aa'}]
for i, x in enumerate(a):
    print(i, next(iter(x)))
[out]
0 x
1 f
2 x
3 f
4 aa

[case testTextIOProperties]
import typing
import sys
print(type(sys.stdin.encoding))
print(type(sys.stdin.errors))
sys.stdin.line_buffering
sys.stdin.buffer
sys.stdin.newlines
[out]
<class 'str'>
<class 'str'>

[case testIOProperties]
import typing
import sys
print(sys.stdin.name)
print(sys.stdin.buffer.mode)
[out]
<stdin>
rb

[case testFromFuturePrintFunction]
from __future__ import print_function
print('a', 'b')
[out]
a b

[case testListMethods]
import typing
import sys
l = [0, 1, 2, 3, 4]
if sys.version >= '3.3':
    l.clear()
else:
    l = []
l.append(0)
print('>', l)
if sys.version >= '3.3':
    m = l.copy()
else:
    m = l[:]
m.extend([1, 2, 3, 4])
print('>', m)
print(l.index(0))
print(l.index(0, 0))
print(l.index(0, 0, 1))
try:
    print(l.index(1))
    print('expected ValueError')
except ValueError:
    pass
l.insert(0, 1)
print('>', l)
print(l.pop(0))
print(l.pop())
m.remove(0)
try:
    m.remove(0)
    print('expected ValueError')
except ValueError:
    pass
m.reverse()
m.sort()
m.sort(key=lambda x: -x)
m.sort(reverse=False)
m.sort(key=lambda x: -x, reverse=True)
print('>', m)
[out]
> [0]
> [0, 1, 2, 3, 4]
0
0
0
> [1, 0]
1
0
> [1, 2, 3, 4]

[case testListOperators]
import typing
l = [0, 1]
print('+', l + [2])
print('*', l * 2)
print('*', 2 * l)
print('in', 1 in l)
print('==', l == [1, 2])
print('!=', l != [1, 2])
print('>', l > [1, 2, 3])
print('>=', l >= [1, 2, 3])
print('<', l < [1, 2, 3])
print('<=', l <= [1, 2, 3])
print('>[0]', l[0])
l += [2]
print('+=', l)
l *= 2
print('*=', l)
print('iter', list(iter(l)))
print('len', len(l))
print('repr', repr(l))
l[:3] = []
print('setslice', l)
print('reversed', list(reversed(l)))
[out]
+ [0, 1, 2]
* [0, 1, 0, 1]
* [0, 1, 0, 1]
in True
== False
!= True
> False
>= False
< True
<= True
>[0] 0
+= [0, 1, 2]
*= [0, 1, 2, 0, 1, 2]
iter [0, 1, 2, 0, 1, 2]
len 6
repr [0, 1, 2, 0, 1, 2]
setslice [0, 1, 2]
reversed [2, 1, 0]

[case testTupleAsSubtypeOfSequence]
from typing import TypeVar, Sequence
T = TypeVar('T')
def f(a: Sequence[T]) -> None: print(a)
f(tuple())
[out]
()

[case testMapWithLambdaSpecialCase]
from typing import List, Iterator
a = [[1], [3]]
b = map(lambda y: y[0], a)
print('>', list(b))
[out]
> [1, 3]

[case testInternalBuiltinDefinition]
import typing
def f(x: _T) -> None: pass
s: FrozenSet
[out]
_program.py:2: error: Name "_T" is not defined
_program.py:3: error: Name "FrozenSet" is not defined

[case testVarArgsFunctionSubtyping]
import typing
def f(*args: str) -> str: return args[0]
map(f, ['x'])
map(f, [1])
[out]
_program.py:4: error: Argument 1 to "map" has incompatible type "Callable[[VarArg(str)], str]"; expected "Callable[[int], str]"

[case testMapStr]
import typing
x = range(3)
a = list(map(str, x))
a + 1
[out]
_testMapStr.py:4: error: No overload variant of "__add__" of "list" matches argument type "int"
_testMapStr.py:4: note: Possible overload variants:
_testMapStr.py:4: note:     def __add__(self, List[str], /) -> List[str]
_testMapStr.py:4: note:     def [_S] __add__(self, List[_S], /) -> List[Union[_S, str]]

[case testRelativeImport]
import typing
from m import x
print(x)
[file m/__init__.py]
from .n import x
[file m/n.py]
x = 1
[out]
1

[case testRelativeImport2]
import typing
from m.n import x
print(x)
[file m/__init__.py]
[file m/n.py]
from .nn import x
[file m/nn.py]
x = 2
[out]
2

[case testPyiTakesPrecedenceOverPy]
import m
m.f(1)
[file m.py]
def f(x):
    print(x)
[file m.pyi]
import typing
def f(x: str) -> None: pass
[out]
_program.py:2: error: Argument 1 to "f" has incompatible type "int"; expected "str"

[case testComplexArithmetic]
import typing
print(5 + 8j)
print(3j * 2.0)
print(4J / 2.0)
[out]
(5+8j)
6j
2j

[case testComplexArithmetic2]
x = 5 + 8j
if int():
    x = '' # E
y = 3j * 2.0
if int():
    y = '' # E
[out]
_program.py:3: error: Incompatible types in assignment (expression has type "str", variable has type "complex")
_program.py:6: error: Incompatible types in assignment (expression has type "str", variable has type "complex")

[case testSuperNew]
from typing import Dict, Any
class MyType(type):
    def __new__(cls, name: str, bases: tuple, namespace: Dict[str, Any]) -> Any:
        return super().__new__(cls, name + 'x', bases, namespace)
class A(metaclass=MyType): pass
print(type(A()).__name__)
[out]
Ax

[case testSubclassBothGenericAndNonGenericABC]
from typing import Generic, TypeVar
from abc import ABCMeta
T = TypeVar('T')
class A(metaclass=ABCMeta): pass
class B(Generic[T]): pass
class C(A, B): pass
class D(B, A): pass
class E(A, B[T], Generic[T]): pass
class F(B[T], A, Generic[T]): pass
def f(e: E[int], f: F[int]) -> None: pass
[out]

[case testTypeVariableTypeComparability]
from typing import TypeVar
T = TypeVar('T')
def eq(x: T, y: T, z: T) -> T:
    if x == y:
        return y
    else:
        return z
print(eq(1, 2, 3))
print(eq('x', 'x', 'z'))
[out]
3
x

[case testIntDecimalCompatibility]
import typing
from decimal import Decimal
print(Decimal(1) + 2)
print(Decimal(1) - 2)
print(1 + Decimal('2.34'))
print(1 - Decimal('2.34'))
print(2 * Decimal('2.34'))
[out]
3
-1
3.34
-1.34
4.68

[case testInstantiateBuiltinTypes]
from typing import Dict, Set, List
d = dict()  # type: Dict[int, str]
s = set()   # type: Set[int]
l = list()  # type: List[int]
str()
bytes()
bytearray()
int()
float()
complex()
slice(1)
bool()

[case testVariableLengthTupleError]
from typing import Tuple
def p(t: Tuple[str, ...]) -> None:
    n = 5
    print(t[n])
    for s in t:
        s()
''.startswith(('x', 'y'))
''.startswith(('x', b'y'))
[out]
_program.py:6: error: "str" not callable
_program.py:8: error: Argument 1 to "startswith" of "str" has incompatible type "Tuple[str, bytes]"; expected "Union[str, Tuple[str, ...]]"

[case testMultiplyTupleByInteger]
n = 4
t = ('',) * n
t + 1
[out]
_program.py:3: error: No overload variant of "__add__" of "tuple" matches argument type "int"
_program.py:3: note: Possible overload variants:
_program.py:3: note:     def __add__(self, Tuple[str, ...], /) -> Tuple[str, ...]
_program.py:3: note:     def [_T] __add__(self, Tuple[_T, ...], /) -> Tuple[Union[str, _T], ...]

[case testMultiplyTupleByIntegerReverse]
n = 4
t = n * ('',)
t + 1
[out]
_program.py:3: error: No overload variant of "__add__" of "tuple" matches argument type "int"
_program.py:3: note: Possible overload variants:
_program.py:3: note:     def __add__(self, Tuple[str, ...], /) -> Tuple[str, ...]
_program.py:3: note:     def [_T] __add__(self, Tuple[_T, ...], /) -> Tuple[Union[str, _T], ...]

[case testDictWithKeywordArgs]
from typing import Dict, Any, List
d1 = dict(a=1, b=2) # type: Dict[str, int]
d2 = dict(a=1, b='') # type: Dict[str, int] # E
d3 = dict(a=1, b=1)
d3.xyz # E
d4 = dict(a=1, b='') # type: Dict[str, Any]
result = dict(x=[], y=[]) # type: Dict[str, List[str]]
[out]
_program.py:3: error: Dict entry 1 has incompatible type "str": "str"; expected "str": "int"
_program.py:5: error: "Dict[str, int]" has no attribute "xyz"

[case testDefaultDict]
# flags: --new-type-inference
import typing as t
from collections import defaultdict

T = t.TypeVar('T')

d1 = defaultdict(list) # type: t.DefaultDict[int, str]
d2 = defaultdict() # type: t.DefaultDict[int, str]
d2[0] = '0'
d2['0'] = 0

def tst(dct: t.DefaultDict[int, T]) -> T:
    return dct[0]

collections = ['coins', 'stamps', 'comics'] # type: t.List[str]
d3 = defaultdict(str) # type: t.DefaultDict[int, str]
collections[2]

tst(defaultdict(list, {0: []}))
tst(defaultdict(list, {'0': []}))

class MyDDict(t.DefaultDict[int,T], t.Generic[T]):
    pass
MyDDict(dict)['0']
MyDDict(dict)[0]
[out]
_program.py:7: error: Argument 1 to "defaultdict" has incompatible type "Type[List[_T]]"; expected "Optional[Callable[[], str]]"
_program.py:10: error: Invalid index type "str" for "defaultdict[int, str]"; expected type "int"
_program.py:10: error: Incompatible types in assignment (expression has type "int", target has type "str")
_program.py:20: error: Argument 1 to "tst" has incompatible type "defaultdict[str, List[Never]]"; expected "defaultdict[int, List[Never]]"
_program.py:24: error: Invalid index type "str" for "MyDDict[Dict[Never, Never]]"; expected type "int"

[case testCollectionsAliases]
import typing as t
import collections as c

o1 = c.Counter()  # type: t.Counter[int]
reveal_type(o1)
o1['string']

o2 = c.ChainMap()  # type: t.ChainMap[int, str]
reveal_type(o2)

o3 = c.deque()  # type: t.Deque[int]
reveal_type(o3)

o4 = t.Counter[int]()
reveal_type(o4)

o5 = t.ChainMap[int, str]()
reveal_type(o5)

o6 = t.Deque[int]()
reveal_type(o6)

[out]
_testCollectionsAliases.py:5: note: Revealed type is "collections.Counter[builtins.int]"
_testCollectionsAliases.py:6: error: Invalid index type "str" for "Counter[int]"; expected type "int"
_testCollectionsAliases.py:9: note: Revealed type is "collections.ChainMap[builtins.int, builtins.str]"
_testCollectionsAliases.py:12: note: Revealed type is "collections.deque[builtins.int]"
_testCollectionsAliases.py:15: note: Revealed type is "collections.Counter[builtins.int]"
_testCollectionsAliases.py:18: note: Revealed type is "collections.ChainMap[builtins.int, builtins.str]"
_testCollectionsAliases.py:21: note: Revealed type is "collections.deque[builtins.int]"

[case testChainMapUnimported]
ChainMap[int, str]()

[out]
_testChainMapUnimported.py:1: error: Name "ChainMap" is not defined

[case testDequeWrongCase]
import collections
import typing

collections.Deque()
typing.deque()

[out]
_testDequeWrongCase.py:4: error: Module has no attribute "Deque"; maybe "deque"?
_testDequeWrongCase.py:5: error: Module has no attribute "deque"; maybe "Deque"?

[case testDictUpdateInference]
from typing import Dict, Optional
d = {}  # type: Dict[str, Optional[int]]
d.update({str(i): None for i in range(4)})

[case testSuperAndSetattr]
class A:
    def __init__(self) -> None:
        super().__setattr__('a', 1)
        super().__setattr__(1, 'a')
[out]
_program.py:4: error: Argument 1 to "__setattr__" of "object" has incompatible type "int"; expected "str"

[case testMetaclassAndSuper]
from typing import Any

class A(type):
    def __new__(cls, name, bases, namespace) -> Any:
        return super().__new__(cls, '', (object,), {'x': 7})

class B(metaclass=A):
    pass

print(getattr(B(), 'x'))
[out]
7

[case testSortedNoError]
from typing import Iterable, Callable, TypeVar, List, Dict, Optional
T = TypeVar('T')
def sorted(x: Iterable[T], *, key: Optional[Callable[[T], object]] = None) -> None: ...
a = []  # type: List[Dict[str, str]]
sorted(a, key=lambda y: y[''])

[case testAbstractProperty]
from abc import abstractproperty, ABCMeta  # type: ignore[deprecated]
class A(metaclass=ABCMeta):
    @abstractproperty
    def x(self) -> int: pass
class B(A):
    @property
    def x(self) -> int:
        return 3
b = B()
print(b.x + 1)
[out]
4

[case testInferenceWithLambda]
from typing import TypeVar, Iterable, Iterator, List
import itertools

_T = TypeVar('_T')

def f(iterable): # type: (Iterable[_T]) -> Iterator[List[_T]]
    grouped = itertools.groupby(enumerate(iterable), lambda pair: pair[0] // 2)
    return ([elem for _, elem in group] for _, group in grouped)

[case testReModuleBytes]
# Regression tests for various overloads in the re module -- bytes version
import re
bre = b'a+'
bpat = re.compile(bre)
bpat = re.compile(bpat)
s1 = re.search(bre, b'')
assert s1
s1.groups()
re.search(bre, u'') # Error
s2 = re.search(bpat, b'')
assert s2
s2.groups()
re.search(bpat, u'') # Error
# match(), split(), findall(), finditer() are much the same, so skip those.
# sub(), subn() have more overloads and we are checking these:
re.sub(bre, b'', b'') + b''
re.sub(bpat, b'', b'') + b''
re.sub(bre, lambda m: b'', b'') + b''
re.sub(bpat, lambda m: b'', b'') + b''
re.subn(bre, b'', b'')[0] + b''
re.subn(bpat, b'', b'')[0] + b''
re.subn(bre, lambda m: b'', b'')[0] + b''
re.subn(bpat, lambda m: b'', b'')[0] + b''
[out]
_testReModuleBytes.py:9: error: No overload variant of "search" matches argument types "bytes", "str"
_testReModuleBytes.py:9: note: Possible overload variants:
_testReModuleBytes.py:9: note:     def search(pattern: Union[str, Pattern[str]], string: str, flags: Union[int, RegexFlag] = ...) -> Optional[Match[str]]
_testReModuleBytes.py:9: note:     def search(pattern: Union[bytes, Pattern[bytes]], string: Buffer, flags: Union[int, RegexFlag] = ...) -> Optional[Match[bytes]]
_testReModuleBytes.py:13: error: Argument 1 to "search" has incompatible type "Pattern[bytes]"; expected "Union[str, Pattern[str]]"

[case testReModuleString]
# Regression tests for various overloads in the re module -- string version
import re
sre = 'a+'
spat = re.compile(sre)
spat = re.compile(spat)
s1 = re.search(sre, '')
assert s1
s1.groups()
re.search(sre, b'') # Error
s2 = re.search(spat, '')
assert s2
s2.groups()
re.search(spat, b'') # Error
# match(), split(), findall(), finditer() are much the same, so skip those.
# sus(), susn() have more overloads and we are checking these:
re.sub(sre, '', '') + ''
re.sub(spat, '', '') + ''
re.sub(sre, lambda m: '', '') + ''
re.sub(spat, lambda m: '', '') + ''
re.subn(sre, '', '')[0] + ''
re.subn(spat, '', '')[0] + ''
re.subn(sre, lambda m: '', '')[0] + ''
re.subn(spat, lambda m: '', '')[0] + ''
[out]
_testReModuleString.py:9: error: No overload variant of "search" matches argument types "str", "bytes"
_testReModuleString.py:9: note: Possible overload variants:
_testReModuleString.py:9: note:     def search(pattern: Union[str, Pattern[str]], string: str, flags: Union[int, RegexFlag] = ...) -> Optional[Match[str]]
_testReModuleString.py:9: note:     def search(pattern: Union[bytes, Pattern[bytes]], string: Buffer, flags: Union[int, RegexFlag] = ...) -> Optional[Match[bytes]]
_testReModuleString.py:13: error: Argument 1 to "search" has incompatible type "Pattern[str]"; expected "Union[bytes, Pattern[bytes]]"

[case testListSetitemTuple]
from typing import List, Tuple
a = []  # type: List[Tuple[str, int]]
a[0] = 'x', 1
a[1] = 2, 'y'
a[:] = [('z', 3)]
[out]
_program.py:4: error: Incompatible types in assignment (expression has type "Tuple[int, str]", target has type "Tuple[str, int]")

[case testContextManager]
import contextlib
from contextlib import contextmanager
from typing import Iterator

@contextmanager
def f(x: int) -> Iterator[str]:
    yield 'foo'

@contextlib.contextmanager
def g(*x: str) -> Iterator[int]:
    yield 1

reveal_type(f)
reveal_type(g)

with f('') as s:
    reveal_type(s)
[out]
_program.py:13: note: Revealed type is "def (x: builtins.int) -> contextlib._GeneratorContextManager[builtins.str, None, None]"
_program.py:14: note: Revealed type is "def (*x: builtins.str) -> contextlib._GeneratorContextManager[builtins.int, None, None]"
_program.py:16: error: Argument 1 to "f" has incompatible type "str"; expected "int"
_program.py:17: note: Revealed type is "builtins.str"

[case testTypedDictGet]
# Test that TypedDict get plugin works with typeshed stubs
from typing import TypedDict
class A: pass
D = TypedDict('D', {'x': int, 'y': str})
d: D
reveal_type(d.get('x'))
reveal_type(d.get('y'))
reveal_type(d.get('z'))
d.get()
s = ''
reveal_type(d.get(s))
[out]
_testTypedDictGet.py:6: note: Revealed type is "Union[builtins.int, None]"
_testTypedDictGet.py:7: note: Revealed type is "Union[builtins.str, None]"
_testTypedDictGet.py:8: note: Revealed type is "builtins.object"
_testTypedDictGet.py:9: error: All overload variants of "get" of "Mapping" require at least one argument
_testTypedDictGet.py:9: note: Possible overload variants:
_testTypedDictGet.py:9: note:     def get(self, str, /) -> object
_testTypedDictGet.py:9: note:     def [_T] get(self, str, /, default: object) -> object
_testTypedDictGet.py:11: note: Revealed type is "builtins.object"

[case testTypedDictMappingMethods]
from typing import TypedDict
Cell = TypedDict('Cell', {'value': int})
c = Cell(value=42)
for x in c:
    reveal_type(x)
reveal_type(iter(c))
reveal_type(len(c))
reveal_type('value' in c)
reveal_type(c.keys())
reveal_type(c.items())
reveal_type(c.values())
reveal_type(c.copy())
reveal_type(c.setdefault('value', False))
c.update({'value': 2})
c.update({'invalid': 2})
c.pop('value')
c == c
c != c
Cell2 = TypedDict('Cell2', {'value': int}, total=False)
c2 = Cell2()
reveal_type(c2.pop('value'))
[out]
_testTypedDictMappingMethods.py:5: note: Revealed type is "builtins.str"
_testTypedDictMappingMethods.py:6: note: Revealed type is "typing.Iterator[builtins.str]"
_testTypedDictMappingMethods.py:7: note: Revealed type is "builtins.int"
_testTypedDictMappingMethods.py:8: note: Revealed type is "builtins.bool"
_testTypedDictMappingMethods.py:9: note: Revealed type is "_collections_abc.dict_keys[builtins.str, builtins.object]"
_testTypedDictMappingMethods.py:10: note: Revealed type is "_collections_abc.dict_items[builtins.str, builtins.object]"
_testTypedDictMappingMethods.py:11: note: Revealed type is "_collections_abc.dict_values[builtins.str, builtins.object]"
_testTypedDictMappingMethods.py:12: note: Revealed type is "TypedDict('_testTypedDictMappingMethods.Cell', {'value': builtins.int})"
_testTypedDictMappingMethods.py:13: note: Revealed type is "builtins.int"
_testTypedDictMappingMethods.py:15: error: Unexpected TypedDict key "invalid"
_testTypedDictMappingMethods.py:16: error: Key "value" of TypedDict "Cell" cannot be deleted
_testTypedDictMappingMethods.py:21: note: Revealed type is "builtins.int"

[case testCrashOnComplexCheckWithNamedTupleNext]
from typing import NamedTuple, Optional

MyNamedTuple = NamedTuple('MyNamedTuple', [('parent', 'MyNamedTuple')]) # type: ignore
def foo(mymap) -> Optional[MyNamedTuple]:
    return next((mymap[key] for key in mymap), None)
[out]

[case testCanConvertTypedDictToAnySuperclassOfMapping]
from typing import Sized, TypedDict, Iterable, Container

Point = TypedDict('Point', {'x': int, 'y': int})

p: Point
s: Sized = p
it: Iterable[str] = p
c: Container[str] = p
o: object = p
it2: Iterable[int] = p
[out]
_testCanConvertTypedDictToAnySuperclassOfMapping.py:10: error: Incompatible types in assignment (expression has type "Point", variable has type "Iterable[int]")
_testCanConvertTypedDictToAnySuperclassOfMapping.py:10: note: Following member(s) of "Point" have conflicts:
_testCanConvertTypedDictToAnySuperclassOfMapping.py:10: note:     Expected:
_testCanConvertTypedDictToAnySuperclassOfMapping.py:10: note:         def __iter__(self) -> Iterator[int]
_testCanConvertTypedDictToAnySuperclassOfMapping.py:10: note:     Got:
_testCanConvertTypedDictToAnySuperclassOfMapping.py:10: note:         def __iter__(self) -> Iterator[str]

[case testAsyncioGatherPreciseType-xfail]
# Mysteriously regressed in #11905
import asyncio
from typing import Tuple

async def get_location(arg: str) -> Tuple[str, str]:
    return arg, arg

async def main() -> None:
    ((a_x, a_y),) = await asyncio.gather(get_location('start'))
    reveal_type(a_x)
    reveal_type(a_y)
reveal_type(asyncio.gather(*[asyncio.sleep(1), asyncio.sleep(1)]))
[out]
_testAsyncioGatherPreciseType.py:9: note: Revealed type is "builtins.str"
_testAsyncioGatherPreciseType.py:10: note: Revealed type is "builtins.str"
_testAsyncioGatherPreciseType.py:11: note: Revealed type is "asyncio.futures.Future[builtins.list[Any]]"

[case testMultipleInheritanceWorksWithTupleTypeGeneric]
from typing import SupportsAbs, NamedTuple

class Point(NamedTuple('Point', [('x', int), ('y', int)]), SupportsAbs[int]):
    def __abs__(p) -> int:
        return abs(p.x) + abs(p.y)

def test(a: Point) -> bool:
    return abs(a) == 2
[out]

[case testNoCrashOnGenericUnionUnpacking]
from typing import Union, Dict

TEST = {'key': ('a', 'b')}
def test() -> None:
    a, b = TEST.get('foo', ('x', 'y'))
    reveal_type(a)
    reveal_type(b)
def test2() -> None:
    a, b = TEST.get('foo', (1, 2))
    reveal_type(a)
    reveal_type(b)

x: Union[Dict[int, int], Dict[str, str]] = dict(a='b')
for a, b in x.items():
    reveal_type(a)
    reveal_type(b)
[out]
_testNoCrashOnGenericUnionUnpacking.py:6: note: Revealed type is "builtins.str"
_testNoCrashOnGenericUnionUnpacking.py:7: note: Revealed type is "builtins.str"
_testNoCrashOnGenericUnionUnpacking.py:10: note: Revealed type is "Union[builtins.str, builtins.int]"
_testNoCrashOnGenericUnionUnpacking.py:11: note: Revealed type is "Union[builtins.str, builtins.int]"
_testNoCrashOnGenericUnionUnpacking.py:15: note: Revealed type is "Union[builtins.int, builtins.str]"
_testNoCrashOnGenericUnionUnpacking.py:16: note: Revealed type is "Union[builtins.int, builtins.str]"

[case testMetaclassOpAccess]
from typing import Type
class A:
    pass

class Meta(type):
    def __mul__(self, other: int) -> Type[A]:
        pass
    def __add__(self, other: int) -> Type[C]:
        pass
    def __radd__(self, other: int) -> Type[C]:
        pass
class C(metaclass=Meta):
    pass

bar: Type[C]
def get_c_type() -> Type[C]:
    pass

res = bar * 4
other = 4 + get_c_type() + 5
reveal_type(res)
reveal_type(other)
[out]
_testMetaclassOpAccess.py:21: note: Revealed type is "Type[_testMetaclassOpAccess.A]"
_testMetaclassOpAccess.py:22: note: Revealed type is "Type[_testMetaclassOpAccess.C]"

[case testMetaclassOpAccessUnion]
from typing import Type, Union

class MetaA(type):
    def __mul__(self, other: int) -> str:
        pass
class A(metaclass=MetaA):
    pass
class MetaB(type):
    def __mul__(self, other: int) -> int:
        pass
class B(metaclass=MetaB):
    pass

bar: Type[Union[A, B]]
res = bar * 4
reveal_type(res)
[out]
_testMetaclassOpAccessUnion.py:16: note: Revealed type is "Union[builtins.str, builtins.int]"

[case testMetaclassOpAccessAny]
from typing import Type
from nonexistent import C
bar: Type[C]

bar * 4 + bar + 3  # should not produce more errors
[out]
_testMetaclassOpAccessAny.py:2: error: Cannot find implementation or library stub for module named "nonexistent"
_testMetaclassOpAccessAny.py:2: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports

[case testEnumIterationAndPreciseElementType]
# Regression test for #2305
from enum import Enum
class E(Enum):
    A = 'a'
(reveal_type(e) for e in E)
for e in E:
    reveal_type(e)
[out]
_testEnumIterationAndPreciseElementType.py:5: note: Revealed type is "_testEnumIterationAndPreciseElementType.E"
_testEnumIterationAndPreciseElementType.py:7: note: Revealed type is "_testEnumIterationAndPreciseElementType.E"

[case testEnumIterable]
from enum import Enum
from typing import Iterable
class E(Enum):
    A = 'a'
def f(ie: Iterable[E]):
    pass
f(E)

[case testIntEnumIterable]
from enum import IntEnum
from typing import Iterable
class N(IntEnum):
    X = 1
def f(ni: Iterable[N]):
    pass
def g(ii: Iterable[int]):
    pass
f(N)
g(N)
reveal_type(list(N))
[out]
_testIntEnumIterable.py:11: note: Revealed type is "builtins.list[_testIntEnumIterable.N]"

[case testDerivedEnumIterable]
from enum import Enum
from typing import Iterable
class E(str, Enum):
    A = 'foo'
def f(ei: Iterable[E]):
    pass
def g(si: Iterable[str]):
    pass
f(E)
g(E)

[case testInvalidSlots]
from typing import List
class A:
    __slots__ = 1
class B:
    __slots__ = (1, 2)
class C:
    __slots__: List[int] = []
[out]
_testInvalidSlots.py:3: error: Invalid type for "__slots__" (actual type "int", expected type "Union[str, Iterable[str]]")
_testInvalidSlots.py:5: error: Invalid type for "__slots__" (actual type "Tuple[int, int]", expected type "Union[str, Iterable[str]]")
_testInvalidSlots.py:7: error: Invalid type for "__slots__" (actual type "List[int]", expected type "Union[str, Iterable[str]]")

[case testDictWithStarStarSpecialCase]
from typing import Dict

def f() -> Dict[int, str]:
    return {1: '', **d()}

def d() -> Dict[int, int]:
    return {}
[out]
_testDictWithStarStarSpecialCase.py:4: error: Unpacked dict entry 1 has incompatible type "Dict[int, int]"; expected "SupportsKeysAndGetItem[int, str]"

[case testLoadsOfOverloads]
from typing import overload, Any, TypeVar, Iterable, List, Dict, Callable, Union

S = TypeVar('S')
T = TypeVar('T')

@overload
def simple_map() -> None: ...
@overload
def simple_map(func: Callable[[T], S], one: Iterable[T]) -> S: ...
@overload
def simple_map(func: Callable[..., S], *iterables: Iterable[Any]) -> S: ...
def simple_map(*args): pass

def format_row(*entries: object) -> str: pass

class DateTime: pass
JsonBlob = Dict[str, Any]
Column = Union[List[str], List[int], List[bool], List[float], List[DateTime], List[JsonBlob]]

def print_custom_table() -> None:
    a: Column

    for row in simple_map(format_row, a, a, a, a, a, a, a, a):  # 8 columns
        reveal_type(row)
[out]
_testLoadsOfOverloads.py:24: note: Revealed type is "builtins.str"

[case testReduceWithAnyInstance]
from typing import Iterable
from functools import reduce
M = Iterable
def f(m1: M, m2):
    ...
def g(ms: 'T[M]') -> None:
    reduce(f, ms)
T = Iterable
[out]

[case testNamedTupleNew]
# This is an eval test because there was a snag found only with full stubs
from typing import NamedTuple

Base = NamedTuple('Base', [('param', int)])

class Child(Base):
    def __new__(cls, param: int = 1) -> 'Child':
        return Base.__new__(cls, param)

Base(param=10)
Child(param=10)
reveal_type(Child())

from collections import namedtuple
X = namedtuple('X', ['a', 'b'])
x = X(a=1, b='s')

[out]
_testNamedTupleNew.py:12: note: Revealed type is "Tuple[builtins.int, fallback=_testNamedTupleNew.Child]"

[case testNamedTupleTypeInheritanceSpecialCase]
from typing import NamedTuple, Tuple
from collections import namedtuple

A = NamedTuple('A', [('param', int)])
B = namedtuple('B', ['param'])

def accepts_named_tuple(arg: NamedTuple):
    reveal_type(arg._asdict())
    reveal_type(arg._fields)
    reveal_type(arg._field_defaults)

a = A(1)
b = B(1)

accepts_named_tuple(a)
accepts_named_tuple(b)
accepts_named_tuple(1)
accepts_named_tuple((1, 2))
[out]
_testNamedTupleTypeInheritanceSpecialCase.py:8: note: Revealed type is "builtins.dict[builtins.str, Any]"
_testNamedTupleTypeInheritanceSpecialCase.py:9: note: Revealed type is "builtins.tuple[builtins.str, ...]"
_testNamedTupleTypeInheritanceSpecialCase.py:10: note: Revealed type is "builtins.dict[builtins.str, Any]"
_testNamedTupleTypeInheritanceSpecialCase.py:17: error: Argument 1 to "accepts_named_tuple" has incompatible type "int"; expected "NamedTuple"
_testNamedTupleTypeInheritanceSpecialCase.py:18: error: Argument 1 to "accepts_named_tuple" has incompatible type "Tuple[int, int]"; expected "NamedTuple"

[case testNewAnalyzerBasicTypeshed_newsemanal]
from typing import Dict, List, Tuple

x: Dict[str, List[int]]
reveal_type(x['test'][0])
[out]
_testNewAnalyzerBasicTypeshed_newsemanal.py:4: note: Revealed type is "builtins.int"

[case testNewAnalyzerTypedDictInStub_newsemanal]
import stub
reveal_type(stub.thing)

[file stub.pyi]
from typing_extensions import TypedDict

class StuffDict(TypedDict):
    foo: str
    bar: int

def thing(stuff: StuffDict) -> int: ...

[out]
_testNewAnalyzerTypedDictInStub_newsemanal.py:2: note: Revealed type is "def (stuff: TypedDict('stub.StuffDict', {'foo': builtins.str, 'bar': builtins.int})) -> builtins.int"

[case testStrictEqualityAllowlist]
# mypy: strict-equality
{1} == frozenset({1})
frozenset({1}) == {1}

frozenset({1}) == [1]  # Error

{1: 2}.keys() == {1}
{1: 2}.keys() == frozenset({1})
{1: 2}.items() == {(1, 2)}

{1: 2}.keys() == {'no'}  # OK
{1: 2}.values() == {2}  # Error
{1: 2}.keys() == [1]  # OK
[out]
_testStrictEqualityAllowlist.py:5: error: Non-overlapping equality check (left operand type: "FrozenSet[int]", right operand type: "List[int]")
_testStrictEqualityAllowlist.py:12: error: Non-overlapping equality check (left operand type: "dict_values[int, int]", right operand type: "Set[int]")

[case testUnreachableWithStdlibContextManagers]
# mypy: warn-unreachable, strict-optional

from contextlib import suppress

# This test overlaps with some of the warn-unreachable tests in check-unreachable-code,
# but 'open(...)' is a very common function so we want to make sure we don't regress
# against it specifically
def f_open() -> str:
    with open("foo.txt", "r") as f:
        return f.read()
    print("noop")

# contextlib.suppress is less common, but it's a fairly prominent example of an
# exception-suppressing context manager, so it'd be good to double-check.
def f_suppresses() -> int:
    with suppress(Exception):
        return 3
    print("noop")
[out]
_testUnreachableWithStdlibContextManagers.py:11: error: Statement is unreachable
_testUnreachableWithStdlibContextManagers.py:15: error: Missing return statement

[case testUnreachableWithStdlibContextManagersNoStrictOptional]
# mypy: warn-unreachable, no-strict-optional

from contextlib import suppress

# When strict-optional is disabled, 'open' should still behave in the same way as before
def f_open() -> str:
    with open("foo.txt", "r") as f:
        return f.read()
    print("noop")

# ...but unfortunately, we can't
def f_suppresses() -> int:
    with suppress(Exception):
        return 3
    print("noop")
[out]
_testUnreachableWithStdlibContextManagersNoStrictOptional.py:9: error: Statement is unreachable
_testUnreachableWithStdlibContextManagersNoStrictOptional.py:15: error: Statement is unreachable

[case testIsInstanceAdHocIntersectionWithStrAndBytes]
# mypy: warn-unreachable
x: str
if isinstance(x, bytes):
    reveal_type(x)
y: str
if isinstance(x, int):
    reveal_type(x)
[out]
_testIsInstanceAdHocIntersectionWithStrAndBytes.py:3: error: Subclass of "str" and "bytes" cannot exist: would have incompatible method signatures
_testIsInstanceAdHocIntersectionWithStrAndBytes.py:4: error: Statement is unreachable
_testIsInstanceAdHocIntersectionWithStrAndBytes.py:6: error: Subclass of "str" and "int" cannot exist: would have incompatible method signatures
_testIsInstanceAdHocIntersectionWithStrAndBytes.py:7: error: Statement is unreachable

[case testAsyncioFutureWait]
# mypy: strict-optional
from asyncio import Future, wait
from typing import List

async def foo() -> None:
    f = []  # type: List[Future[None]]
    await wait(f)

[case testShadowTypingModule]
1 + ''
[file typing.py]
x = 0
1 + ''
[out]
mypy: "tmp/typing.py" shadows library module "typing"
note: A user-defined top-level module with name "typing" is not supported

[case testIgnoreImportIfNoPython3StubAvailable]
# flags: --ignore-missing-imports
import scribe  # No Python 3 stubs available for scribe
from scribe import x
import pytz  # Python 3 stubs available for pytz
import foobar_asdf
import jack  # This has a stubs package but was never bundled with mypy, so ignoring works
[out]
_testIgnoreImportIfNoPython3StubAvailable.py:4: error: Library stubs not installed for "pytz"
_testIgnoreImportIfNoPython3StubAvailable.py:4: note: Hint: "python3 -m pip install types-pytz"
_testIgnoreImportIfNoPython3StubAvailable.py:4: note: (or run "mypy --install-types" to install all missing stub packages)
_testIgnoreImportIfNoPython3StubAvailable.py:4: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports

[case testNoPython3StubAvailable]
import scribe
from scribe import x
import pytz
[out]
_testNoPython3StubAvailable.py:1: error: Cannot find implementation or library stub for module named "scribe"
_testNoPython3StubAvailable.py:1: note: See https://mypy.readthedocs.io/en/stable/running_mypy.html#missing-imports
_testNoPython3StubAvailable.py:3: error: Library stubs not installed for "pytz"
_testNoPython3StubAvailable.py:3: note: Hint: "python3 -m pip install types-pytz"
_testNoPython3StubAvailable.py:3: note: (or run "mypy --install-types" to install all missing stub packages)


[case testTypingOrderedDictAlias]
from typing import OrderedDict
x: OrderedDict[str, int] = OrderedDict({})
reveal_type(x)
[out]
_testTypingOrderedDictAlias.py:3: note: Revealed type is "collections.OrderedDict[builtins.str, builtins.int]"

[case testTypingExtensionsOrderedDictAlias]
from typing_extensions import OrderedDict
x: OrderedDict[str, str] = OrderedDict({})
reveal_type(x)  # Revealed type is "collections.OrderedDict[builtins.str, builtins.int]"
[out]
_testTypingExtensionsOrderedDictAlias.py:3: note: Revealed type is "collections.OrderedDict[builtins.str, builtins.str]"

[case testSpecialTypingProtocols]
# flags: --warn-unreachable
from typing import Awaitable, Hashable, Union, Tuple, List

obj: Union[Tuple[int], List[int]]
if isinstance(obj, Hashable):
    reveal_type(obj)
if isinstance(obj, Awaitable):
    reveal_type(obj)
[out]
_testSpecialTypingProtocols.py:6: note: Revealed type is "Tuple[builtins.int]"
_testSpecialTypingProtocols.py:8: error: Statement is unreachable

[case testTypeshedRecursiveTypesExample]
from typing import List, Union

Recursive = Union[str, List["Recursive"]]

def foo(r: Recursive) -> None:
    if not isinstance(r, str):
        if r:
            foo(r[0])
    if not isinstance(r, list):
        r.casefold()

foo("")
foo(list(""))
foo(list((list(""), "")))
[out]

[case testNarrowTypeForDictKeys]
from typing import Dict, KeysView, Optional

d: Dict[str, int]
key: Optional[str]
if key in d.keys():
    reveal_type(key)
else:
    reveal_type(key)

kv: KeysView[str]
k: Optional[str]
if k in kv:
    reveal_type(k)
else:
    reveal_type(k)

[out]
_testNarrowTypeForDictKeys.py:6: note: Revealed type is "builtins.str"
_testNarrowTypeForDictKeys.py:8: note: Revealed type is "Union[builtins.str, None]"
_testNarrowTypeForDictKeys.py:13: note: Revealed type is "builtins.str"
_testNarrowTypeForDictKeys.py:15: note: Revealed type is "Union[builtins.str, None]"

[case testTypeAliasWithNewStyleUnion]
# flags: --python-version 3.10
from typing import Literal, Type, TypeAlias, TypeVar

Foo = Literal[1, 2]
reveal_type(Foo)
Bar1 = Foo | Literal[3]
Bar2 = Literal[3] | Foo
Bar3 = Foo | Foo | Literal[3] | Foo

U1 = int | str
U2 = U1 | bytes
U3 = bytes | U1

Opt1 = None | int
Opt2 = None | float
Opt3 = int | None
Opt4 = float | None

A = Type[int] | str
B: TypeAlias = Type[int] | str
C = type[int] | str

D = type[int] | str
x: D
reveal_type(x)
E: TypeAlias = type[int] | str
y: E
reveal_type(y)
F = list[type[int] | str]

T = TypeVar("T", int, str)
def foo(x: T) -> T:
    A = type[int] | str
    a: A
    return x
[out]
_testTypeAliasWithNewStyleUnion.py:5: note: Revealed type is "typing._SpecialForm"
_testTypeAliasWithNewStyleUnion.py:25: note: Revealed type is "Union[Type[builtins.int], builtins.str]"
_testTypeAliasWithNewStyleUnion.py:28: note: Revealed type is "Union[Type[builtins.int], builtins.str]"

[case testTypeAliasWithNewStyleUnionInStub]
import m
a: m.A
reveal_type(a)
b: m.B
reveal_type(b)
c: m.C
reveal_type(c)
d: m.D
reveal_type(d)
e: m.E
reveal_type(e)
f: m.F
reveal_type(f)

[file m.pyi]
from typing import Type, Callable, Literal
from typing_extensions import TypeAlias

Foo = Literal[1, 2]
reveal_type(Foo)
Bar1 = Foo | Literal[3]
Bar2 = Literal[3] | Foo
Bar3 = Foo | Foo | Literal[3] | Foo

U1 = int | str
U2 = U1 | bytes
U3 = bytes | U1

Opt1 = None | int
Opt2 = None | float
Opt3 = int | None
Opt4 = float | None

A = Type[int] | str
B: TypeAlias = Type[int] | str
C = type[int] | str
reveal_type(C)
D: TypeAlias = type[int] | str
E = str | type[int]
F: TypeAlias = str | type[int]
G = list[type[int] | str]
H = list[str | type[int]]

CU1 = int | Callable[[], str | bool]
CU2: TypeAlias = int | Callable[[], str | bool]
CU3 = int | Callable[[str | bool], str]
CU4: TypeAlias = int | Callable[[str | bool], str]
[out]
m.pyi:5: note: Revealed type is "typing._SpecialForm"
m.pyi:22: note: Revealed type is "typing._SpecialForm"
_testTypeAliasWithNewStyleUnionInStub.py:3: note: Revealed type is "Union[Type[builtins.int], builtins.str]"
_testTypeAliasWithNewStyleUnionInStub.py:5: note: Revealed type is "Union[Type[builtins.int], builtins.str]"
_testTypeAliasWithNewStyleUnionInStub.py:7: note: Revealed type is "Union[Type[builtins.int], builtins.str]"
_testTypeAliasWithNewStyleUnionInStub.py:9: note: Revealed type is "Union[Type[builtins.int], builtins.str]"
_testTypeAliasWithNewStyleUnionInStub.py:11: note: Revealed type is "Union[builtins.str, Type[builtins.int]]"
_testTypeAliasWithNewStyleUnionInStub.py:13: note: Revealed type is "Union[builtins.str, Type[builtins.int]]"

[case testEnumNameWorkCorrectlyOn311]
# flags: --python-version 3.11
import enum

class E(enum.Enum):
    X = 1
    Y = 2
    @enum.property
    def foo(self) -> int: ...

e: E
reveal_type(e.name)
reveal_type(e.value)
reveal_type(E.X.name)
reveal_type(e.foo)
reveal_type(E.Y.foo)
[out]
_testEnumNameWorkCorrectlyOn311.py:11: note: Revealed type is "Union[Literal['X'], Literal['Y']]"
_testEnumNameWorkCorrectlyOn311.py:12: note: Revealed type is "Union[Literal[1]?, Literal[2]?]"
_testEnumNameWorkCorrectlyOn311.py:13: note: Revealed type is "Literal['X']?"
_testEnumNameWorkCorrectlyOn311.py:14: note: Revealed type is "builtins.int"
_testEnumNameWorkCorrectlyOn311.py:15: note: Revealed type is "builtins.int"

[case testTypeAliasNotSupportedWithNewStyleUnion]
# flags: --python-version 3.9
from typing_extensions import TypeAlias
A = type[int] | str
B = str | type[int]
C = str | int
D: TypeAlias = str | int
[out]
_testTypeAliasNotSupportedWithNewStyleUnion.py:3: error: Invalid type alias: expression is not a valid type
_testTypeAliasNotSupportedWithNewStyleUnion.py:3: error: Unsupported left operand type for | ("GenericAlias")
_testTypeAliasNotSupportedWithNewStyleUnion.py:4: error: Invalid type alias: expression is not a valid type
_testTypeAliasNotSupportedWithNewStyleUnion.py:4: error: Unsupported left operand type for | ("Type[str]")
_testTypeAliasNotSupportedWithNewStyleUnion.py:5: error: Invalid type alias: expression is not a valid type
_testTypeAliasNotSupportedWithNewStyleUnion.py:5: error: Unsupported left operand type for | ("Type[str]")
_testTypeAliasNotSupportedWithNewStyleUnion.py:6: error: Invalid type alias: expression is not a valid type
_testTypeAliasNotSupportedWithNewStyleUnion.py:6: error: Unsupported left operand type for | ("Type[str]")

[case testTypedDictUnionGetFull]
from typing import Dict
from typing_extensions import TypedDict

class TD(TypedDict, total=False):
    x: int
    y: int

A = Dict[str, TD]
x: A
def foo(k: str) -> TD:
    reveal_type(x.get(k, {}))
    return x.get(k, {})
[out]
_testTypedDictUnionGetFull.py:11: note: Revealed type is "TypedDict('_testTypedDictUnionGetFull.TD', {'x'?: builtins.int, 'y'?: builtins.int})"

[case testTupleWithDifferentArgsPy310]
# https://github.com/python/mypy/issues/11098
# flags: --python-version 3.10
Correct1 = str | tuple[float, float, str]
Correct2 = tuple[float] | str
Correct3 = tuple[float, ...] | str
Correct4 = tuple[float, str]
Correct5 = tuple[float, ...]
Correct6 = list[tuple[int, str]]
c1: Correct1
c2: Correct2
c3: Correct3
c4: Correct4
c5: Correct5
c6: Correct6
reveal_type(c1)
reveal_type(c2)
reveal_type(c3)
reveal_type(c4)
reveal_type(c5)
reveal_type(c6)

RHSAlias1: type = tuple[int, int]
RHSAlias2: type = tuple[int]
RHSAlias3: type = tuple[int, ...]

WrongTypeElement = str | tuple[float, 1]  # Error
WrongEllipsis = tuple[float, float, ...] | str  # Error

reveal_type(tuple[int, str]((1, "x")))
[out]
_testTupleWithDifferentArgsPy310.py:15: note: Revealed type is "Union[builtins.str, Tuple[builtins.float, builtins.float, builtins.str]]"
_testTupleWithDifferentArgsPy310.py:16: note: Revealed type is "Union[Tuple[builtins.float], builtins.str]"
_testTupleWithDifferentArgsPy310.py:17: note: Revealed type is "Union[builtins.tuple[builtins.float, ...], builtins.str]"
_testTupleWithDifferentArgsPy310.py:18: note: Revealed type is "Tuple[builtins.float, builtins.str]"
_testTupleWithDifferentArgsPy310.py:19: note: Revealed type is "builtins.tuple[builtins.float, ...]"
_testTupleWithDifferentArgsPy310.py:20: note: Revealed type is "builtins.list[Tuple[builtins.int, builtins.str]]"
_testTupleWithDifferentArgsPy310.py:26: error: Invalid type: try using Literal[1] instead?
_testTupleWithDifferentArgsPy310.py:27: error: Unexpected "..."
_testTupleWithDifferentArgsPy310.py:29: note: Revealed type is "Tuple[builtins.int, builtins.str]"

[case testEnumIterMetaInference]
import socket
from enum import Enum
from typing import Iterable, Iterator, Type, TypeVar

_E = TypeVar("_E", bound=Enum)

def enum_iter(cls: Type[_E]) -> Iterable[_E]:
    reveal_type(iter(cls))
    reveal_type(next(iter(cls)))
    return iter(cls)

for value in enum_iter(socket.SocketKind):
    reveal_type(value)
[out]
_testEnumIterMetaInference.py:8: note: Revealed type is "typing.Iterator[_E`-1]"
_testEnumIterMetaInference.py:9: note: Revealed type is "_E`-1"
_testEnumIterMetaInference.py:13: note: Revealed type is "socket.SocketKind"

[case testEnumUnpackedViaMetaclass]
from enum import Enum

class FooEnum(Enum):
    A = 1
    B = 2
    C = 3

a, b, c = FooEnum
reveal_type(a)
reveal_type(b)
reveal_type(c)
[out]
_testEnumUnpackedViaMetaclass.py:9: note: Revealed type is "_testEnumUnpackedViaMetaclass.FooEnum"
_testEnumUnpackedViaMetaclass.py:10: note: Revealed type is "_testEnumUnpackedViaMetaclass.FooEnum"
_testEnumUnpackedViaMetaclass.py:11: note: Revealed type is "_testEnumUnpackedViaMetaclass.FooEnum"

[case testNativeIntTypes]
# Spot check various native int operations with full stubs.
from mypy_extensions import i64, i32

x: i64 = 0
y: int = x
x = i64(0)
y = int(x)
i64()
i64("12")
i64("ab", 16)
i64(1.2)
float(i64(1))

i64(1) + i32(2)  # Error
reveal_type(x + y)
reveal_type(y + x)
a = [0]
a[x]
[out]
_testNativeIntTypes.py:14: error: Unsupported operand types for + ("i64" and "i32")
_testNativeIntTypes.py:15: note: Revealed type is "mypy_extensions.i64"
_testNativeIntTypes.py:16: note: Revealed type is "mypy_extensions.i64"

[case testStarUnpackNestedUnderscore]
from typing import Tuple, Dict, List

def crash() -> None:
    d: Dict[int, Tuple[str, int, str]] = {}
    k, (v1, *_) = next(iter(d.items()))

def test1() -> None:
    vs: List[str]
    d: Dict[int, Tuple[str, int, int]] = {}
    k, (v1, *vs) = next(iter(d.items()))
    reveal_type(vs)

def test2() -> None:
    d: Dict[int, Tuple[str, int, str]] = {}
    k, (v1, *vs) = next(iter(d.items()))
    reveal_type(vs)
[out]
_testStarUnpackNestedUnderscore.py:10: error: List item 0 has incompatible type "int"; expected "str"
_testStarUnpackNestedUnderscore.py:10: error: List item 1 has incompatible type "int"; expected "str"
_testStarUnpackNestedUnderscore.py:11: note: Revealed type is "builtins.list[builtins.str]"
_testStarUnpackNestedUnderscore.py:16: note: Revealed type is "builtins.list[builtins.object]"

[case testStrictEqualitywithParamSpec]
# flags: --strict-equality
from typing import Generic
from typing_extensions import Concatenate, ParamSpec

P = ParamSpec("P")

class Foo(Generic[P]): ...
class Bar(Generic[P]): ...

def bad(foo: Foo[[int]], bar: Bar[[int]]) -> bool:
    return foo == bar

def bad1(foo1: Foo[[int]], foo2: Foo[[str]]) -> bool:
    return foo1 == foo2

def bad2(foo1: Foo[[int, str]], foo2: Foo[[int, bytes]]) -> bool:
    return foo1 == foo2

def bad3(foo1: Foo[[int]], foo2: Foo[[int, int]]) -> bool:
    return foo1 == foo2

def good4(foo1: Foo[[int]], foo2: Foo[[int]]) -> bool:
    return foo1 == foo2

def good5(foo1: Foo[[int]], foo2: Foo[[bool]]) -> bool:
    return foo1 == foo2

def good6(foo1: Foo[[int, int]], foo2: Foo[[bool, bool]]) -> bool:
    return foo1 == foo2

def good7(foo1: Foo[[int]], foo2: Foo[P], *args: P.args, **kwargs: P.kwargs) -> bool:
    return foo1 == foo2

def good8(foo1: Foo[P], foo2: Foo[[int, str, bytes]], *args: P.args, **kwargs: P.kwargs) -> bool:
    return foo1 == foo2

def good9(foo1: Foo[Concatenate[int, P]], foo2: Foo[[int, str, bytes]], *args: P.args, **kwargs: P.kwargs) -> bool:
    return foo1 == foo2

[out]
_testStrictEqualitywithParamSpec.py:11: error: Non-overlapping equality check (left operand type: "Foo[[int]]", right operand type: "Bar[[int]]")
_testStrictEqualitywithParamSpec.py:14: error: Non-overlapping equality check (left operand type: "Foo[[int]]", right operand type: "Foo[[str]]")
_testStrictEqualitywithParamSpec.py:17: error: Non-overlapping equality check (left operand type: "Foo[[int, str]]", right operand type: "Foo[[int, bytes]]")
_testStrictEqualitywithParamSpec.py:20: error: Non-overlapping equality check (left operand type: "Foo[[int]]", right operand type: "Foo[[int, int]]")

[case testInferenceOfDunderDictOnClassObjects]
class Foo: ...
reveal_type(Foo.__dict__)
reveal_type(Foo().__dict__)
Foo.__dict__ = {}
Foo().__dict__ = {}

[out]
_testInferenceOfDunderDictOnClassObjects.py:2: note: Revealed type is "types.MappingProxyType[builtins.str, Any]"
_testInferenceOfDunderDictOnClassObjects.py:3: note: Revealed type is "builtins.dict[builtins.str, Any]"
_testInferenceOfDunderDictOnClassObjects.py:4: error: Property "__dict__" defined in "type" is read-only
_testInferenceOfDunderDictOnClassObjects.py:4: error: Incompatible types in assignment (expression has type "Dict[Never, Never]", variable has type "MappingProxyType[str, Any]")

[case testTypeVarTuple]
# flags: --python-version=3.11
from typing import Any, Callable, Unpack, TypeVarTuple

Ts = TypeVarTuple("Ts")

def foo(callback: Callable[[], Any]) -> None:
    call(callback)

def call(callback: Callable[[Unpack[Ts]], Any], *args: Unpack[Ts]) -> Any:
    ...

[case testTypeVarTupleTypingExtensions]
from typing_extensions import Unpack, TypeVarTuple
from typing import Any, Callable

Ts = TypeVarTuple("Ts")

def foo(callback: Callable[[], Any]) -> None:
    call(callback)

def call(callback: Callable[[Unpack[Ts]], Any], *args: Unpack[Ts]) -> Any:
    ...

[case testDataclassReplace]
from dataclasses import dataclass, replace

@dataclass
class A:
    x: int

a = A(x=42)
a2 = replace(a, x=42)
reveal_type(a2)
a2 = replace()
a2 = replace(a, x='spam')
a2 = replace(a, x=42, q=42)
[out]
_testDataclassReplace.py:9: note: Revealed type is "_testDataclassReplace.A"
_testDataclassReplace.py:10: error: Too few arguments for "replace"
_testDataclassReplace.py:11: error: Argument "x" to "replace" of "A" has incompatible type "str"; expected "int"
_testDataclassReplace.py:12: error: Unexpected keyword argument "q" for "replace" of "A"

[case testGenericInferenceWithTuple]
# flags: --new-type-inference
from typing import TypeVar, Callable, Tuple

T = TypeVar("T")

def f(x: Callable[..., T]) -> T:
    return x()

x: Tuple[str, ...] = f(tuple)
[out]

[case testGenericInferenceWithDataclass]
# flags: --new-type-inference
from typing import Any, Collection, List
from dataclasses import dataclass, field

class Foo:
    pass

@dataclass
class A:
    items: Collection[Foo] = field(default_factory=list)
[out]

[case testGenericInferenceWithItertools]
# flags: --new-type-inference
from typing import TypeVar, Tuple
from itertools import groupby
K = TypeVar("K")
V = TypeVar("V")

def fst(kv: Tuple[K, V]) -> K:
    k, v = kv
    return k

pairs = [(len(s), s) for s in ["one", "two", "three"]]
grouped = groupby(pairs, key=fst)
[out]

[case testDataclassReplaceOptional]
from dataclasses import dataclass, replace
from typing import Optional

@dataclass
class A:
    x: Optional[int]

a = A(x=42)
reveal_type(a)
a2 = replace(a, x=None)  # OK
reveal_type(a2)
[out]
_testDataclassReplaceOptional.py:9: note: Revealed type is "_testDataclassReplaceOptional.A"
_testDataclassReplaceOptional.py:11: note: Revealed type is "_testDataclassReplaceOptional.A"

[case testDataclassStrictOptionalAlwaysSet]
from dataclasses import dataclass
from typing import Callable, Optional

@dataclass
class Description:
    name_fn: Callable[[Optional[int]], Optional[str]]

def f(d: Description) -> None:
    reveal_type(d.name_fn)
[out]
_testDataclassStrictOptionalAlwaysSet.py:9: note: Revealed type is "def (Union[builtins.int, None]) -> Union[builtins.str, None]"

[case testPEP695VarianceInference]
# flags: --python-version=3.12
from typing import Callable, Final

class Job[_R_co]:
    def __init__(self, target: Callable[[], _R_co]) -> None:
        self.target: Final = target

def func(
    action: Job[int | None],
    a1: Job[int | None],
    a2: Job[int],
    a3: Job[None],
) -> None:
    action = a1
    action = a2
    action = a3
    a2 = action  # Error
[out]
_testPEP695VarianceInference.py:17: error: Incompatible types in assignment (expression has type "Job[None]", variable has type "Job[int]")

[case testPEP695TypeAliasWithDifferentTargetTypes]
# flags: --python-version=3.12
from typing import Any, Callable, List, Literal, TypedDict, overload, TypeAlias, TypeVar, Never

class C[T]: pass

class O[T]:
    @overload
    def __init__(self) -> None: ...
    @overload
    def __init__(self, x: int) -> None: ...
    def __init__(self, x: int = 0) -> None:
        pass

class TD(TypedDict):
    x: int

S = TypeVar("S")
A = list[S]
B: TypeAlias = list[S]

type A1 = type[int]
type A2 = type[int] | None
type A3 = None | type[int]
type A4 = type[Any]
type A5 = type[C] | None
type A6 = None | type[C]
type A7 = type[O] | None
type A8 = None | type[O]

type B1[**P, R] = Callable[P, R] | None
type B2[**P, R] = None | Callable[P, R]
type B3 = Callable[[str], int]
type B4 = Callable[..., int]

type C1 = A1 | None
type C2 = None | A1

type D1 = Any | None
type D2 = None | Any

type E1 = List[int]
type E2 = List[int] | None
type E3 = None | List[int]

type F1 = Literal[1]
type F2 = Literal['x'] | None
type F3 = None | Literal[True]

type G1 = tuple[int, Any]
type G2 = tuple[int, Any] | None
type G3 = None | tuple[int, Any]

type H1 = TD
type H2 = TD | None
type H3 = None | TD

type I1 = C[int]
type I2 = C[Any] | None
type I3 = None | C[TD]
type I4 = O[int] | None
type I5 = None | O[int]

type J1[T] = T | None
type J2[T] = None | T
type J3[*Ts] = tuple[*Ts]
type J4[T] = J1[T] | None
type J5[T] = None | J1[T]
type J6[*Ts] = J3[*Ts] | None

type K1 = A[int] | None
type K2 = None | A[int]
type K3 = B[int] | None
type K4 = None | B[int]

type L1 = Never
type L2 = list[Never]

[case testPEP695VarianceInferenceSpecialCaseWithTypeshed]
# flags: --python-version=3.12
class C1[T1, T2](list[T1]):
    def m(self, a: T2) -> None: ...

def func1(p: C1[int, object]):
    x: C1[int, int] = p

class C2[T1, T2, T3](dict[T2, T3]):
    def m(self, a: T1) -> None: ...

def func2(p: C2[object, int, int]):
    x: C2[int, int, int] = p

class C3[T1, T2](tuple[T1, ...]):
    def m(self, a: T2) -> None: ...

def func3(p: C3[int, object]):
    x: C3[int, int] = p


[case testDynamicClassAttribute]
# Some things that can break if DynamicClassAttribute isn't handled properly
from types import DynamicClassAttribute
from enum import Enum

class TestClass:
    @DynamicClassAttribute
    def name(self) -> str: ...

class TestClass2(TestClass, Enum): ...

class Status(Enum):
    ABORTED = -1

def imperfect(status: Status) -> str:
    return status.name.lower()

[case testUnpackIteratorBuiltins]
# Regression test for https://github.com/python/mypy/issues/18320
# Caused by https://github.com/python/typeshed/pull/12851
x = [1, 2]
reveal_type([*reversed(x)])
reveal_type([*map(str, x)])
[out]
_testUnpackIteratorBuiltins.py:4: note: Revealed type is "builtins.list[builtins.int]"
_testUnpackIteratorBuiltins.py:5: note: Revealed type is "builtins.list[builtins.str]"