From davidluebeck at gmx.net  Sat Jan 23 12:58:37 2016
From: davidluebeck at gmx.net (=?UTF-8?B?RGF2aWQgTMO8YmVjaw==?=)
Date: Sat, 23 Jan 2016 18:58:37 +0100
Subject: [python-muc] Test runner checking for absence of 'None' in all
 functions
Message-ID: <56A3BF4D.7060102@gmx.net>

Dear fellow Munich Pythonistas,

I am currently reading a book [1] that gives the following coding tip:
"Prefer	Exceptions to Returning	None". You can see code examples out of
the book further below.

As I am teaching myself pytest these days, I would like to write a test
runner (which eventually is to be part of a Continuous Integration
setup) that fails should it detect any function that returns None.

My problem is that I would like to limit the test runner to look
*inside* of functions (and/or other structures).

I can very well write a parser that checks, per line, if the words
"return" and "None" are used. But that would cover the entire file in
question, never mind its structure.

Do you have any ideas how to test for the 'absence of None' within
functions and the like?

I am looking forward to your suggestions!

Greetings and thanks,

David




# bad code
def divide(a, b):
    try:
        return a / b
    except ZeroDivisionError:
	return None


# good code
def divide(a, b):
    try:
	return a / b
    except ZeroDivisionError as e:
	raise ValueError(?Invalid inputs?) from	e


[1] Brett Slatkin (2015), Effective Python, Addison-Wesley

From h.goebel at goebel-consult.de  Sun Jan 24 14:41:25 2016
From: h.goebel at goebel-consult.de (Hartmut Goebel)
Date: Sun, 24 Jan 2016 20:41:25 +0100
Subject: [python-muc] Test runner checking for absence of 'None' in all
 functions
In-Reply-To: <56A3BF4D.7060102@gmx.net>
References: <56A3BF4D.7060102@gmx.net>
Message-ID: <56A528E5.4010202@goebel-consult.de>

Am 23.01.2016 um 18:58 schrieb David L?beck:
> Do you have any ideas how to test for the 'absence of None' within
> functions and the like?

Ich habe zwar nicht genau verstanden, aus Du pr?fen willst. Aber du
kommst wahrscheinlich nicht umhin, die Module zu parsen.

Wenn Du auf bestimmte Code-Muster Aktionen ausf?hren m?chtest, k?nntest
Du das evtl. mit den "fixes" aus lib2to3 erschlagen. Wahrscheinlich gibt
es noch andere Parser, die Du benutzen k?nntest und deren "Matching"
einfacher ist. Z.B. spark - bei dem ich aber nicht wei?, ob es die
aktuelle Syntax komplett beherrscht.

-- 
Sch?nen Gru?
Hartmut Goebel
Dipl.-Informatiker (univ), CISSP, CSSLP
Information Security Management, Security Governance, Secure Software
Development

Goebel Consult, Landshut
http://www.goebel-consult.de

Blog: http://www.goebel-consult.de/blog/verschlusselte-mailingslisten
Kolumne:
http://www.cissp-gefluester.de/2012-09-steht-ein-manta-fahrer-vor-der-uni

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mail.python.org/pipermail/python-muc/attachments/20160124/1ecb21f9/attachment.html>