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From Thomas Vander Stichele <tho...@apestaart.org>
Subject unit testing view/show functions
Date Sun, 27 Dec 2009 19:09:17 GMT
Hi everyone,

this is my first mail to this list.  Let's start by saying that I think
CouchDB is wonderful!

I've been playing with it to write a Getting Things Done application so
that I can use it on my laptop, my two desktops, and my N900 phone.  So
far the good part.

The bad part currently is that I have a lot of friction when trying to
write view/show functions.  Simple mistakes in my js code trigger
strange and cryptic warnings and problems in couchdb.  Without going
into much detail, the things that have happened to me:

 - long waits, OS timeout errors from couchdb log
 - couchdb view server completely crashing, resulting in a 404 (with the
next request then connecting, but still failing)
 - long strings of numbers, longer than my terminal buffer, which I
think (with my limited knowledge of Erlang) are actual text documents
(in erlang, a string is really an array of numbers, right ?), but get
printed in this non-readable base format, filling up my terminal
scrollback buffer so I can't even see the errors in front of it.

These are problems triggered by simple mistakes (referencing an
undefined 'name', accessing a property that doesn't exist, ...) which in
other languages I'm used to would simply tell me so when I run the
files.

It helps to run 'js' on the files before even pushing the files to my
couchdb server, but even then I can still make other mistakes.  And
frankly, the whole cycle of write-save-couchapp push-switch to
browser-reload page-switch to couchdb terminal to see error is
error-prone; often I realize on the refresh that I either forgot to save
the new .js file or push it to the server.

So I thought it would make sense to add some unit tests to test my show
and view functions.

It turns out this is not a very obvious thing to do.  Most javascript
unit test frameworks are browser-based.  I found JSUnit which can indeed
be run with spidermonkey.

However, I've been racking my brain trying to figure out how I can make
js load for example a show function file, which contains an anonymous
function body, store it in a function object, then execute it:

 - spidermonkey has a function called 'load', but that reads and
executes the file; since the function is anonymous, it doesn't get
stored
 - eval would work, since it returns the result of the last statement,
which in this case is the anonymous function definition; hence the
function.  However, it doesn't seem like spidermonkey js gives me any
way to actually load files.

So, I'm kind of surprised.  Is anyone of you out there doing any kind of
unit testing against the .js code they write for views and shows and
maps and reduces ? I haven't even started on writing some tests for my
date formatting code, but I'd be annoyed if there was no good way to do
it in the future.

Here's hoping someone has done something that works and can point me to
some source code repository as an example.

Thanks!
Thomas

-- 
And I know
they all look so good from a distance
but I tell you I'm the one
--
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