pytest.raises(Exception) is what you need.

Code

import pytest

def test_passes():
    with pytest.raises(Exception) as e_info:
        x = 1 / 0

def test_passes_without_info():
    with pytest.raises(Exception):
        x = 1 / 0

def test_fails():
    with pytest.raises(Exception) as e_info:
        x = 1 / 1

def test_fails_without_info():
    with pytest.raises(Exception):
        x = 1 / 1

# Don't do this. Assertions are caught as exceptions.
def test_passes_but_should_not():
    try:
        x = 1 / 1
        assert False
    except Exception:
        assert True

# Even if the appropriate exception is caught, it is bad style,
# because the test result is less informative
# than it would be with pytest.raises(e)
# (it just says pass or fail.)

def test_passes_but_bad_style():
    try:
        x = 1 / 0
        assert False
    except ZeroDivisionError:
        assert True

def test_fails_but_bad_style():
    try:
        x = 1 / 1
        assert False
    except ZeroDivisionError:
        assert True

Output

============================================================================================= test session starts ==============================================================================================
platform linux2 -- Python 2.7.6 -- py-1.4.26 -- pytest-2.6.4
collected 7 items 

test.py ..FF..F

=================================================================================================== FAILURES ===================================================================================================
__________________________________________________________________________________________________ test_fails __________________________________________________________________________________________________

    def test_fails():
        with pytest.raises(Exception) as e_info:
>           x = 1 / 1
E           Failed: DID NOT RAISE

test.py:13: Failed
___________________________________________________________________________________________ test_fails_without_info ____________________________________________________________________________________________

    def test_fails_without_info():
        with pytest.raises(Exception):
>           x = 1 / 1
E           Failed: DID NOT RAISE

test.py:17: Failed
___________________________________________________________________________________________ test_fails_but_bad_style ___________________________________________________________________________________________

    def test_fails_but_bad_style():
        try:
            x = 1 / 1
>           assert False
E           assert False

test.py:43: AssertionError
====================================================================================== 3 failed, 4 passed in 0.02 seconds ======================================================================================

Note that e_info saves the exception object so you can extract details from it. For example, if you want to check the exception call stack or another nested exception inside.

The biggest difference is that pytest.fail() can't be caught and assert can:

for example - this test is going to pass:

def test_assert():
    try:
        assert False
    except:
        pass

and this test is going to fail:

def test_pytest_fail():
    try:
        pytest.fail('failed')
    except Exception:
        pass

Other than that I don't think there are more major differences because they both raise an AssertionError.

Anyway, I would suggest you use this library https://pypi.org/project/assertpy/ for more cleaner and readable assertions.

**** EDIT: ****

Guess I was wrong:

pytest.fail() can be caught by catching the specific exception Failed or just 'BaseException.

So - they both are ways to raise exceptions but from some reason Failed does not inherit from the generic Exception type. so pytest.fail() raises Failed exception and not AssertionError

I'm confused why you think this is related to assertion rewriting. An assert False should cause an AssertionError in Python - rewritten or not, and even outside of pytest. All rewriting does is showing additional context when the assertion fails.

It sounds like something is broken in your Python environment. Possibly you're using PYTHONOPTIMIZE / -O?