pytest/testing/test_compat.py

# mypy: allow-untyped-defs
from __future__ import annotations

import enum
from functools import cached_property
from functools import partial
from functools import wraps
from typing import TYPE_CHECKING

from _pytest.compat import assert_never
from _pytest.compat import get_real_func
from _pytest.compat import safe_getattr
from _pytest.compat import safe_isclass
from _pytest.outcomes import OutcomeException
import pytest


if TYPE_CHECKING:
    from typing_extensions import Literal


def test_real_func_loop_limit() -> None:
    class Evil:
        def __init__(self):
            self.left = 1000

        def __repr__(self):
            return f"<Evil left={self.left}>"

        def __getattr__(self, attr):
            if not self.left:
                raise RuntimeError("it's over")  # pragma: no cover
            self.left -= 1
            return self

    evil = Evil()

    with pytest.raises(
        ValueError,
        match=("wrapper loop when unwrapping <Evil left=998>"),
    ):
        get_real_func(evil)


def test_get_real_func() -> None:
    """Check that get_real_func correctly unwraps decorators until reaching the real function"""

    def decorator(f):
        @wraps(f)
        def inner():
            pass  # pragma: no cover

        return inner

    def func():
        pass  # pragma: no cover

    wrapped_func = decorator(decorator(func))
    assert get_real_func(wrapped_func) is func

    wrapped_func2 = decorator(decorator(wrapped_func))
    assert get_real_func(wrapped_func2) is func

    # obtain the function up until the point a function was wrapped by pytest itself
    @pytest.fixture
    def wrapped_func3():
        pass  # pragma: no cover

    wrapped_func4 = decorator(wrapped_func3)
    assert get_real_func(wrapped_func4) is wrapped_func3._get_wrapped_function()


def test_get_real_func_partial() -> None:
    """Test get_real_func handles partial instances correctly"""

    def foo(x):
        return x

    assert get_real_func(foo) is foo
    assert get_real_func(partial(foo)) is foo


class ErrorsHelper:
    @property
    def raise_baseexception(self):
        raise BaseException("base exception should be raised")

    @property
    def raise_exception(self):
        raise Exception("exception should be caught")

    @property
    def raise_fail_outcome(self):
        pytest.fail("fail should be caught")


def test_helper_failures() -> None:
    helper = ErrorsHelper()
    with pytest.raises(Exception):  # noqa: B017
        _ = helper.raise_exception
    with pytest.raises(OutcomeException):
        _ = helper.raise_fail_outcome


def test_safe_getattr() -> None:
    helper = ErrorsHelper()
    assert safe_getattr(helper, "raise_exception", "default") == "default"
    assert safe_getattr(helper, "raise_fail_outcome", "default") == "default"
    with pytest.raises(BaseException):  # noqa: B017
        assert safe_getattr(helper, "raise_baseexception", "default")


def test_safe_isclass() -> None:
    assert safe_isclass(type) is True

    class CrappyClass(Exception):
        # Type ignored because it's bypassed intentionally.
        @property  # type: ignore
        def __class__(self):
            assert False, "Should be ignored"

    assert safe_isclass(CrappyClass()) is False


def test_cached_property() -> None:
    ncalls = 0

    class Class:
        @cached_property
        def prop(self) -> int:
            nonlocal ncalls
            ncalls += 1
            return ncalls

    c1 = Class()
    assert ncalls == 0
    assert c1.prop == 1
    assert c1.prop == 1
    c2 = Class()
    assert ncalls == 1
    assert c2.prop == 2
    assert c1.prop == 1


def test_assert_never_union() -> None:
    x: int | str = 10

    if isinstance(x, int):
        pass
    else:
        with pytest.raises(AssertionError):
            assert_never(x)  # type: ignore[arg-type]

    if isinstance(x, int):
        pass
    elif isinstance(x, str):
        pass
    else:
        assert_never(x)


def test_assert_never_enum() -> None:
    E = enum.Enum("E", "a b")
    x: E = E.a

    if x is E.a:
        pass
    else:
        with pytest.raises(AssertionError):
            assert_never(x)  # type: ignore[arg-type]

    if x is E.a:
        pass
    elif x is E.b:
        pass
    else:
        assert_never(x)


def test_assert_never_literal() -> None:
    x: Literal["a", "b"] = "a"

    if x == "a":
        pass
    else:
        with pytest.raises(AssertionError):
            assert_never(x)  # type: ignore[arg-type]

    if x == "a":
        pass
    elif x == "b":
        pass
    else:
        assert_never(x)