test-data/unit/check-type-checks.test

-- Conditional type checks.


[case testSimpleIsinstance]
x = None  # type: object
n = None  # type: int
s = None  # type: str
if int():
    n = x # E: Incompatible types in assignment (expression has type "object", variable has type "int")
if isinstance(x, int):
    n = x
    s = x # E: Incompatible types in assignment (expression has type "int", variable has type "str")
if int():
    n = x # E: Incompatible types in assignment (expression has type "object", variable has type "int")
[builtins fixtures/isinstance.pyi]

[case testSimpleIsinstance2]
import typing
def f(x: object, n: int, s: str) -> None:
    if int():
        n = x # E: Incompatible types in assignment (expression has type "object", variable has type "int")
        if isinstance(x, int):
            n = x
            s = x # E: Incompatible types in assignment (expression has type "int", variable has type "str")
        n = x # E: Incompatible types in assignment (expression has type "object", variable has type "int")
[builtins fixtures/isinstance.pyi]
[out]

[case testSimpleIsinstance3]
class A:
    x = None  # type: object
    n = None  # type: int
    s = None  # type: str
    if int():
        n = x # E: Incompatible types in assignment (expression has type "object", variable has type "int")
    if isinstance(x, int):
        n = x
        s = x # E: Incompatible types in assignment (expression has type "int", variable has type "str")
    else:
        n = x # E: Incompatible types in assignment (expression has type "object", variable has type "int")
[builtins fixtures/isinstance.pyi]
[out]

[case testMultipleIsinstanceTests]
import typing
class A: pass
class B(A): pass
def f(x: object, a: A, b: B, c: int) -> None:
    if isinstance(x, A):
        if isinstance(x, B):
            b = x
            x = a
        a = x
        c = x # E: Incompatible types in assignment (expression has type "A", variable has type "int")
[builtins fixtures/isinstance.pyi]
[out]

[case testMultipleIsinstanceTests2]
import typing
class A: pass
class B(A): pass
def f(x: object, y: object, n: int, s: str) -> None:
    if isinstance(x, int):
        if isinstance(y, str):
            n = x
            s = y
            s = x # E: Incompatible types in assignment (expression has type "int", variable has type "str")
            n = y # E: Incompatible types in assignment (expression has type "str", variable has type "int")
        s = y # E: Incompatible types in assignment (expression has type "object", variable has type "str")
        n = y # E: Incompatible types in assignment (expression has type "object", variable has type "int")
        n = x
[builtins fixtures/isinstance.pyi]
[out]

[case testIsinstanceAndElif]
import typing
def f(x: object, n: int, s: str) -> None:
    if int():
        n = x # E: Incompatible types in assignment (expression has type "object", variable has type "int")
        if isinstance(x, int):
            n = x
            s = x # E: Incompatible types in assignment (expression has type "int", variable has type "str")
        elif isinstance(x, str):
            s = x
            n = x # E: Incompatible types in assignment (expression has type "str", variable has type "int")
        else:
            n = x # E: Incompatible types in assignment (expression has type "object", variable has type "int")
            s = x # E: Incompatible types in assignment (expression has type "object", variable has type "str")
        n = x # E: Incompatible types in assignment (expression has type "object", variable has type "int")
[builtins fixtures/isinstance.pyi]
[out]

[case testIsinstanceAndAnyType]
from typing import Any
def f(x: Any, n: int, s: str) -> None:
    if int():
        s = x
        if isinstance(x, int):
            n = x
            s = x # E: Incompatible types in assignment (expression has type "int", variable has type "str")
        s = x
[builtins fixtures/isinstance.pyi]
[out]

[case testIsinstanceAndGenericType]
from typing import TypeVar, Generic
T = TypeVar('T')
class C(Generic[T]):
    def f(self, x: T) -> None: pass
def f(x: object) -> None:
    if isinstance(x, C):
        x.f(1)
        x.f('')
        x.g() # E: "C[Any]" has no attribute "g"
    x.g() # E: "object" has no attribute "g"
[builtins fixtures/isinstance.pyi]
[out]