test-data/unit/check-warnings.test

-- Test cases for warning generation.

-- Redundant casts
-- ---------------

[case testRedundantCast]
# flags: --warn-redundant-casts
from typing import cast
a = 1
b = cast(str, a)
c = cast(int, a)
[out]
main:5: error: Redundant cast to "int"

[case testRedundantCastWithIsinstance]
# flags: --warn-redundant-casts
from typing import cast, Union
x = 1  # type: Union[int, str]
if isinstance(x, str):
    cast(str, x)
[builtins fixtures/isinstance.pyi]
[out]
main:5: error: Redundant cast to "str"

[case testCastToSuperclassNotRedundant]
# flags: --warn-redundant-casts
from typing import cast, TypeVar, List
T = TypeVar('T')
def add(xs: List[T], ys: List[T]) -> List[T]: pass
class A: pass
class B(A): pass
a = A()
b = B()
# Without the cast, the following line would fail to type check.
c = add([cast(A, b)], [a])
[builtins fixtures/list.pyi]

[case testCastToAnyTypeNotRedundant]
# flags: --warn-redundant-casts
from typing import cast, Any
a: Any
b = cast(Any, a)
[builtins fixtures/list.pyi]

[case testCastToObjectNotRedunant]
# flags: --warn-redundant-casts
from typing import cast

a = 1
b = cast(object, 1)

[case testCastFromLiteralRedundant]
# flags: --warn-redundant-casts
from typing import cast

cast(int, 1)
[out]
main:4: error: Redundant cast to "int"

[case testCastFromUnionOfAnyOk]
# flags: --warn-redundant-casts
from typing import Any, cast, Union

x = Any
y = Any
z = Any

def f(q: Union[x, y, z]) -> None:
    cast(Union[x, y], q)

-- Unused 'type: ignore' comments
-- ------------------------------

[case testUnusedTypeIgnore]
# flags: --warn-unused-ignores
a = 1
if int():
    a = 'a' # type: ignore
if int():
    a = 2 # type: ignore # E: Unused "type: ignore" comment
if int():
    a = 'b' # E: Incompatible types in assignment (expression has type "str", variable has type "int")

[case testUnusedTypeIgnoreImport]
# flags: --warn-unused-ignores
import banana # type: ignore
import m # type: ignore
from m import * # type: ignore
[file m.py]
pass
[out]
main:3: error: Unused "type: ignore" comment
main:4: error: Unused "type: ignore" comment


-- No return
-- ---------

[case testNoReturn]
# flags: --warn-no-return
def f() -> int:
    pass

def g() -> int:
    if bool():
        return 1
[builtins fixtures/list.pyi]
[out]
main:5: error: Missing return statement

[case testNoReturnWhile]
# flags: --warn-no-return
def h() -> int:
    while True:
        if bool():
            return 1

def i() -> int:
    while 1:
        if bool():
            return 1
        if bool():
            break

def j() -> int:
    while 1:
        if bool():
            return 1
        if bool():
            continue
[builtins fixtures/list.pyi]
[out]
main:7: error: Missing return statement

[case testNoReturnExcept]
# flags: --warn-no-return
def f() -> int:
    try:
        return 1
    except:
        pass
def g() -> int:
    try:
        pass
    except:
        return 1
    else:
        return 1
def h() -> int:
    try:
        pass
    except:
        pass
    else:
        pass
    finally:
        return 1
[builtins fixtures/exception.pyi]
[out]
main:2: error: Missing return statement

[case testNoReturnEmptyBodyWithDocstring]
def f() -> int:
    """Return the number of peppers."""
    # This might be an @abstractmethod, for example
    pass
[out]


-- Returning Any
-- -------------

[case testReturnAnyFromTypedFunction]
# flags: --warn-return-any
from typing import Any
def g() -> Any: pass
def f() -> int: return g()
[out]
main:4: error: Returning Any from function declared to return "int"

[case testReturnAnyForNotImplementedInBinaryMagicMethods]
# flags: --warn-return-any
class A:
    def __eq__(self, other: object) -> bool: return NotImplemented
[builtins fixtures/notimplemented.pyi]
[out]

[case testReturnAnyForNotImplementedInNormalMethods]
# flags: --warn-return-any
class A:
    def some(self) -> bool: return NotImplemented
[builtins fixtures/notimplemented.pyi]
[out]
main:3: error: Returning Any from function declared to return "bool"

[case testReturnAnyFromTypedFunctionWithSpecificFormatting]
# flags: --warn-return-any
from typing import Any, Tuple
typ = Tuple[int, int, int, int, int, int, int, int, int, int, int, int, int,
            int, int, int, int, int, int, int, int, int, int, int, int, int,
            int, int, int, int, int, int, int, int, int, int, int, int, int,
            int, int, int, int, int, int, int, int, int, int, int, int, int,
            int, int, int, int, int, int, int, int, int, int, int, int, int,
            int, int, int, int, int, int, int, int, int, int, int, int, int,
            int, int, int, int, int, int, int, int, int, int, int, int, int]
def g() -> Any: pass
def f() -> typ: return g()
[builtins fixtures/tuple.pyi]
[out]
main:11: error: Returning Any from function declared to return "tuple[int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int, int]"

[case testReturnAnySilencedFromTypedFunction]
# flags: --warn-return-any
from typing import Any
def g() -> Any: pass
def f() -> int:
    result = g() # type: int
    return result
[out]

[case testReturnAnyFromUntypedFunction]
# flags: --warn-return-any
from typing import Any
def g() -> Any: pass
def f(): return g()
[out]

[case testReturnAnyFromAnyTypedFunction]
# flags: --warn-return-any
from typing import Any
def g() -> Any: pass
def f() -> Any: return g()
[out]

[case testOKReturnAnyIfProperSubtype]
# flags: --warn-return-any
from typing import Any, Optional

class Test(object):

    def __init__(self) -> None:
        self.attr = "foo"  # type: Any

    def foo(self, do_it: bool) -> Optional[Any]:
        if do_it:
            return self.attr  # Should not warn here
        else:
            return None
[builtins fixtures/list.pyi]
[out]

[case testReturnAnyDeferred]
# flags: --warn-return-any
def foo(a1: A) -> int:
    if a1._x:
        return 1
    n = 1
    return n

class A:
    def __init__(self, x: int) -> None:
        self._x = x