[openstack-dev] [all] add cyclomatic complexity check to pep8 target

Joe Gordon joe.gordon0 at gmail.com
Fri Oct 17 03:40:01 UTC 2014


On Thu, Oct 16, 2014 at 8:11 PM, Angus Salkeld <asalkeld at mirantis.com>
wrote:

> Hi all
>
> I came across some tools [1] & [2] that we could use to make sure we don't
> increase our code complexity.
>
> Has anyone had any experience with these or other tools?
>


Flake8 (and thus hacking) has built in McCabe Complexity checking.

flake8 --select=C --max-complexity 10

https://github.com/flintwork/mccabe
http://flake8.readthedocs.org/en/latest/warnings.html

Example on heat: http://paste.openstack.org/show/121561
Example in nova (max complexity of 20):
http://paste.openstack.org/show/121562


>
> radon is the underlying reporting tool and xenon is a "monitor" - meaning
> it will fail if a threshold is reached.
>
> To save you the time:
> radon cc -nd heat
> heat/engine/stack.py
>     M 809:4 Stack.delete - E
>     M 701:4 Stack.update_task - D
> heat/engine/resources/server.py
>     M 738:4 Server.handle_update - D
>     M 891:4 Server.validate - D
> heat/openstack/common/jsonutils.py
>     F 71:0 to_primitive - D
> heat/openstack/common/config/generator.py
>     F 252:0 _print_opt - D
> heat/tests/v1_1/fakes.py
>     M 240:4 FakeHTTPClient.post_servers_1234_action - F
>
> It ranks the complexity from A (best) upwards, the command above (-nd)
> says only show D or worse.
> If you look at these methods they are getting out of hand and are
> becoming difficult to understand.
> I like the idea of having a threshold that says we are not going to just
> keep adding to the complexity
> of these methods.
>
> This can be enforced with:
> xenon --max-absolute E heat
> ERROR:xenon:block "heat/tests/v1_1/fakes.py:240 post_servers_1234_action"
> has a rank of F
>
> [1] https://pypi.python.org/pypi/radon
> [2] https://pypi.python.org/pypi/xenon
>
> If people are open to this, I'd like to add these to the test-requirements
> and trial this in Heat
> (as part of the pep8 tox target).
>

I think the idea of gating on complexity is a great idea and would like to
see nova adopt this as well. But why not just use flake8's built in stuff?


>
> Regards
> Angus
>
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>
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