Proposal: Charm testing for 2.0

Thu Mar 17 14:02:25 UTC 2016

On Thu, Mar 17, 2016 at 9:08 AM Tom Barber <tom at analytical-labs.com> wrote:

> Its taken me about 2 weeks of on and off testing to get 4 unit tests
> working, getting everything to play ball is hard, so it would be good!
> Maybe I'll write a blog post about it once I'm done.
>

Fantastic! Do you have a link to these? Would love to see how these

>
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> On 17 March 2016 at 12:24, Merlijn Sebrechts <merlijn.sebrechts at gmail.com>
> wrote:
>
>> As an aside; is there a good write-up somewhere about charm unit testing.
>> I'd like to do this but I'm not sure how to do this. I am completely new to
>> unit testing so I'm having a hard time to see how a good unittest for a
>> Charm would look like and what exactly should be tested.
>>
>> 2016-03-17 1:52 GMT+01:00 Marco Ceppi <marco.ceppi at canonical.com>:
>>
>>> Hello everyone!
>>>
>>> This is an email I've been meaning to write for a while, and have
>>> rewritten a few times now. With 2.0 on the horizon and the charm ecosystem
>>> rapidly growing, I couldn't keep the idea to myself any longer.
>>>
>>> # tl;dr:
>>>
>>> We should stop writing Amulet tests in charms and instead only write
>>> them Bundles and force charms to do unit-testing (when possible) and
>>> promote that all charms be included in bundles in the store.
>>>
>>> # Problem
>>>
>>> Without making this a novel, charm-testing and amulet started before
>>> bundles were even a construct in Juju with a spec written before Juju 1.0.
>>> Since then, many new comers to the ecosystem have remarked how odd it is to
>>> be writing deployment validations at the charm level. Indeed, as years have
>>> gone by and new tools have sprung up it's become clear that; having an
>>> author try to model all the permutations of a charms deployment and do the
>>> physical deploys at that charm level are tedious and incomplete at best.
>>>
>>> With the explosion of layers and improvements to uniting test in charms
>>> at that component level, I feel that continuing to create these bespoke
>>> "bundles" via amulet in a single charm will not be a robust solution going
>>> forward. As we sprint closer to Juju 2.0 we're seeing a higher demand for
>>> assurance of working scenarios, and a sharp focus on quality at every
>>> level. As such I'd like to propose the following policy changes:
>>>
>>> - All bundles must have tests before promulgation to the store
>>> - All charms need to have comprehensive tests (unit or amulet)
>>> - All charms should be included in a bundle
>>>
>>> I'll break down my reasoning and examples in the following sections:
>>>
>>> # All bundles must have tests before promulgation to the store
>>>
>>> Writing bundle tests with Amulet is actually a more compelling story
>>> today than writing an Amulet test case for a charm. As an example, there's
>>> a new ELK stack bundle being produced, here's what the test for that bundle
>>> looks like:
>>> https://github.com/juju-solutions/bundle-elk-stack/blob/master/tests/10-test-bundle
>>>
>>> This makes a lot of sense because it's asserting that the bundle is
>>> working as expected by the Author who put the bundle together. It's also
>>> loading the bundle.yaml as the deployment spec meaning as the bundle
>>> evolves the tests will make sure they continue to run as expected. Also,
>>> this could potentially be used in future smoke tests for charms being
>>> updated if a CI process swaps out, say elasticsearch, for a newer version
>>> of a charm being reviewed. We can assert that both the unittests in
>>> elasticsearch work and it operates properly in an existing real world
>>> solution a la the bundle.
>>>
>>> Additional examples:
>>> -
>>> https://github.com/juju-solutions/bundle-realtime-syslog-analytics/blob/master/tests/01-bundle.py
>>> -
>>> https://github.com/juju-solutions/bundle-apache-core-batch-processing/blob/master/tests/01-bundle.py
>>>
>>> # All charms need to have comprehensive tests (unit or amulet)
>>>
>>> This is just a clarification and more strongly typed policy change that
>>> require charms have (preferred) unit tests or, if not applicable, then an
>>> Amulet test. Bash doesn't really allow for unittesting, so in those
>>> scenarios, Amulet tests would function as a valid testing case.
>>>
>>> There are also some charms which will not make sense as a bundle. One
>>> example is the recently promulgated Fiche charm:
>>> http://bazaar.launchpad.net/~charmers/charms/trusty/fiche/trunk/view/head:/tests/10-deploy It's
>>> a standalone pastebin, but it's an awesome service that provides deployment
>>> validation with an Amulet test. The test stands up the charm, exercises
>>> configuration, and validates the service responds in an expected way. For
>>> scenarios where a charm does not have a bundle an Amulet test would be
>>> required.
>>>
>>> Any charm that currently includes an Amulet test is welcome to continue
>>> keeping such a test.
>>>
>>> # All charms should be included in a bundle
>>>
>>> This last one is to underscore that charms need to serve a purpose. This
>>> policy is written as not an absolute, but instead a strongly worded
>>> suggestion as there are always charms that are exceptions to the rules. One
>>> such example is the aforementioned Fiche charm which as a bundle would not
>>> make as much sense, but is still a purposeful charm.
>>>
>>> That being said, most users coming to consume Juju are looking to solve
>>> a problem. Bundles underscore solutions to problems that people can
>>> consume, and get started quicker.
>>>
>>> As such, when new applications are charmed a test of "is this
>>> application something that serves a clear purpose" having a bundle
>>> submitted alongside the charm validates that claim and provides users a way
>>> to immediately get started with a solution.
>>>
>>> # Conclusion
>>>
>>> These policy changes, once accepted, will be targeted at all charms and
>>> bundles in Xenial as well as any new charm submitted after policy
>>> acceptance date for trusty, and finally any charm currently under review
>>> will be encouraged to adhere to the new policy but won't be required.
>>>
>>> # Action items
>>>
>>> I'm seeking feedback on this concept and welcome suggestions for
>>> improvements, questions, dissenting opinions, and any other remarks as well
>>> as votes from ~charmers and feedback from the community at large.
>>>
>>> Thanks,
>>> Marco Ceppi
>>>
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>>>
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