[Pytest-commit] Issue #757: Heavily using decorators in the System under test suppresses exceptions (pytest-dev/pytest)

[Maxim Yaskevich]

New issue 757: Heavily using decorators in the System under test suppresses exceptions
https://bitbucket.org/pytest-dev/pytest/issue/757/heavily-using-decorators-in-the-system

Maxim Yaskevich:

py.test version - ``platform win32 -- Python 2.7.9 -- py-1.4.27 -- pytest-2.7.1``

When a class I write my tests for heavily uses decorators, for instance for implementing a "builder" fluent method interface like below:

```
#!python

from functools import wraps

def fluent(method):
    @wraps(method)
    def inner(self, *args, **kwargs):
        try:
            method(self, *args, **kwargs)

        finally:
            return self

    return inner


class Server(object):
    def __init__(self, host, port=9090):
        self.host = host
        self.port = port
        self.isrunning = False
        self.status = None
        self.response = None

    @fluent
    def start(self):
        self.isrunning = True
        print 'started'

    @fluent
    def request(self, url, context=None):
        assert self.isrunning

        print 'requesting', url, '...'
        self.status, self.response = 404, {'error': 'Page not found'}

    @fluent
    def await_response(self, status):
        print 'assert expected', status, 'got', self.status
        assert status == self.status            # Generates AssertionError


def test_simple():
    Server('localhost', port=9000) \
        .start() \
        .request('/is_prime', {'number': 13}) \
        .await_response(200)

```

the test passes.

I think this is absolutely not fair and dangerous, as it can hide real problems from the people.

The thing that surprised me even more is that ``nose`` didn't get to catch that error either.

Am I missing something?

Please run a test sample in the attachment, and feel free to ask for more details if needed.