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Date: Mon, 08 Apr 2013 13:01:51 -0700
From: Wendall Cada <wendallc@apache.org>
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To: dev@couchdb.apache.org
Subject: Re: Javascript Test Suite
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Once again, great work here Jason. Additionally, this would solve the 
_restart issue, as we can spawn an external process to manage the 
running CouchDB instance used for the tests. I'll follow up in another 
thread on moving some of this forward.

Wendall

On 04/08/2013 10:10 AM, Jason Smith wrote:
> The couchjs npm package (a drop-in Node.js replacement for
> SpiderMonkey) uses synchronous i/o. I had great success using Fibers
> for this.
>
> https://github.com/iriscouch/couchjs/blob/master/couchjs.js#L50-L68
>
> readline() is synchronous. If there is no input in the queue, it
> yields to Fibers (blocking the function). Once input arrives, the
> yield() call finally returns with the data, which readline() returns
> to the caller.
>
> An encouraging fact from this project is that the server-side
> JavaScript (share/server/*.js) worked completely unmodified. It would
> be no problem to use this technique to make a synchronous XHR and run
> the official/historical unit tests in Node.js.
>
> On Mon, Apr 8, 2013 at 2:41 PM, Dale Harvey <dale@arandomurl.com> wrote:
>> We have been looking to reuse the CouchDB javascript tests for PouchDB and
>> extracted them into a seperate npm package
>>
>> https://npmjs.org/package/couchdb-harness
>>
>> The idea was that we could reused the same test suite and throw ours away
>> however it hit a few problems, mostly that the test suite requires a sync
>> api (which caused most of the problems with xhr in the browser couch
>> tests),  I spent a bunch of time converting the test suites to async, they
>> dont map 1-1 because the couch suite is quite imperative and not really
>> split into self contained unit tests.
>>
>> But already have 1000+ tests that test CouchDB, work on the command line
>> and reliably in the browser, I dont think they are suitable for couch right
>> now, but would be happy to do the work so we could share a test suite
>>
>> https://github.com/daleharvey/pouchdb/tree/master/tests
>>
>>
>> On 8 April 2013 15:26, Paul Davis <paul.joseph.davis@gmail.com> wrote:
>>
>>> The first bit I'd like to say is that the use of couchjs was just a
>>> stop gap measure to get the test suite out of the browser. We used to
>>> have to deal with so many browser issues it was just a terrible mess.
>>> The issue with couchjs is much as you've seen that its not a very full
>>> environment for writing tests. So just to be clear that the only real
>>> thing tying us to that as a test platform is that we have a large
>>> amount of JS written already so either we need to make the couchjs
>>> better, use node, or translate tests to something that has a more
>>> useful environment.
>>>
>>> I've been noodling over whether we might be better off to just start
>>> translating everything to Python or something. I've seen suggestions
>>> for Erlang but I personally think Erlang is a terrible language for
>>> writing tests like this (specifically, the code to test ratio is
>>> ungood). If we had something like Python to hack on then I was also
>>> thinking of writing a library function that would start CouchDB as a
>>> slave process which then would remove the need to have the _restart
>>> handler because you could just kill -9 the subprocess and restart it
>>> with maybe a wait for when things boot again.
>>>
>>> I reviewed your feature branch the other day and I'm +1 for pushing
>>> that to master.
>>>
>>> Awesome work, Wendall.
>>>
>>> On Fri, Apr 5, 2013 at 6:57 PM, Wendall Cada <wendallc@apache.org> wrote:
>>>> I wanted to follow up on this.
>>>>
>>>> I've created a feature branch for this and a JIRA issue
>>>> https://issues.apache.org/jira/browse/COUCHDB-1762
>>>>
>>>> Overall, I think the worst problem is that the tests really aren't
>>>> debuggable in any sane way, and logging is essentially useless for most
>>>> things. The only sure way to spot an error most of the time is if it's an
>>>> actual CouchDB bug and shows up in the log. I'm not sure how this can
>>> ever
>>>> be fixed with the current test suite. I'd opt for testing with jasmine,
>>> but
>>>> that would require not using couchjs for the test runner, so for now, I
>>> just
>>>> focused on getting random failures under control.
>>>>
>>>> Paul was kind enough to share some code that he wrote recently to deal
>>> with
>>>> the rampant _restart issues.
>>>>
>>> https://github.com/davisp/couchdb/commit/0cbf6a9cea01eea599524bcdb77dedb322c7ade4
>>>> This is a very sound approach in using a token so you can see if it
>>> actually
>>>> restarts. The current test suite can result in false positives very
>>> easily,
>>>> which leads to test failures. I think this is probably the biggest reason
>>>> for the random failures. In a previous IRC conversation with Bob
>>> (rnewson),
>>>> Jan and I think Benoit (sorry if not the case) _restart was deemed
>>> something
>>>> that should go away. I filed a ticket for it's removal
>>>> https://issues.apache.org/jira/browse/COUCHDB-1714, and as Bob points
>>> out in
>>>> the comments, this is useful for the test suite. I'd argue it's only
>>> useful
>>>> with Paul's patch adding a token. Otherwise, it's just not reliable at
>>> all.
>>>> For the branch I created, instead of using _restart, I did some bash
>>> magic
>>>> with a pipe and stop/start the process through the local run script. This
>>>> has the same drawback of not knowing if CouchDB restarted, or we just
>>> got a
>>>> false positive. To account for this, I put a small delay in the
>>> execution of
>>>> the lookup, using a new method isRunning to give a little time to stop.
>>>>
>>>> I also changed the suite to run a new couchjs for each test file. I'm not
>>>> certain at this point that this is even necessary at all, but I still
>>> think
>>>> it's safer in case of a crash, since the rest of the suite can continue.
>>>>
>>>> Other changes I made were just timing related in running the test suite
>>> for
>>>> spinning disks, and a couple bug fixes in individual tests.
>>>>
>>>> The lack of timers makes writing these tests very ugly. I really dislike
>>>> this, but so long as the test suite needs couchjs, I don't see a way to
>>>> avoid this without implementing our own setInterval method in C.
>>>>
>>>> One last item. I was getting a consistent failure in Centos 6. I tracked
>>>> this down to a bug in libcurl. For some reason, after any xhr request
>>> that
>>>> returns a 416, the very next send() will hang for a long time, then
>>>> eventually crash couchjs. The specific version causing the issue is
>>>> curl-7.19.7-35.el6 and libcurl-7.19.7-35.el6. I'm not certain if this is
>>>> worth reporting in JIRA, but it will certainly cause a test suite failure
>>>> consistently in attachment_ranges, but otherwise appears to be fairly
>>>> harmless. Maybe this should be documented somewhere?
>>>>
>>>> Wendall
>>>>
>>>>
>>>> On 03/27/2013 02:05 PM, Wendall Cada wrote:
>>>>> In 1.3.0, there is a new part of the test suite to run the javascript
>>>>> tests from the command line. I'm running into various issues on
>>> different
>>>>> hardware/OS configurations. Mostly, tests hanging or timing out and
>>> failing.
>>>>> These are really hard to troubleshoot, as they all pass just fine if run
>>>>> individually.
>>>>>
>>>>> What I'm experimenting with today is rewriting how the tests are
>>>>> implemented to be run one at a time from a loop in bash, versus a loop
>>> in
>>>>> javascript. I think the failures I'm running into are improper
>>>>> setup/teardown. There may be an issue with rapid delete and adding a
>>> db, or
>>>>> rapidly starting and stopping couchdb, but I think this is not what's
>>>>> happening in my failures.
>>>>>
>>>>> The nature of spidermonkey doesn't allow for spawning threads, or
>>>>> sandboxing, etc, so it's hard looking at the test suite to see how I can
>>>>> improve running all tests. I think it's far better to have the setup
>>> spawn a
>>>>> new interpreter for each test. Tear down will kill the interpreter.
>>>>>
>>>>> Wendall
>>>>
>
>
> --
> Iris Couch