(and about tests) Re: Pedantic pickling error after reload?
no-spam at non-existing.invalid
Tue Mar 2 12:11:10 CET 2010
>> well, reloading is the thing which I do most in coding practice :-)
>> For me its a basic thing like cell proliferation in biology.
> I simply never do it. It has subtle issues, one of them you found,
> others you say you work around by introducing actual frameworks. But you
> might well forget some corner-cases & suddently chase a chimera you deem
> a bug, that in fact is just an unwanted side-effect of reloading.
well, at dev time there is a different rule: the more bugs, the better
(they can raise/indicate certain design and coding weaknesses)
> And all this extra complexity is only good for the process of actually
> changing the code. It doesn't help you maintaining code quality.
neither does a improved editor, interactive/debugging/reload
scheme replace tests, nor do tests replace them the other way
around. different dimensions. just the benefactions on all levels
radiate recursively of course ...
e.g. by a good reload scheme one can even work the tests out
better (and debug more efficiently when the tests bump).
that little reload support code is a rather constant small stub
compared to the app size (unless with trivial 1-day apps maybe).
Most 'utility' modules don't need extra care at all.
Plus maybe 1 .. 5 extra lines per few frequently changed GUI
classes (when well organized) and some 5..10 lines for
preserving/re-fixing the few application data anchors. Thats all.
No need to get it fully consistent, as serves its purpose when
editing during runtime is possible in 'most cases'. And most edit
cases during debug sessions are typically just small fixes and
touches of function code. One fix revealing the next follow-up bug
.. beautifying things .. as it is.
critical data structure changes are very rare occasions.
A general reload scheme ("edit at runtime") zeroes out most
effectively a core time consumer while exploring, iterating,
debugging, smoothing ..
On the time scale of these tasks, this effect can in my opinion by
far not be matched equivalently by setup code of whatever kind in
non-trivial apps. (As I did/do this before or with less dynamic
>> I typically need just 1 full app reboot on 20..50 edit-run-cycles I
>> guess. And just few unit test runs per release. Even for
>> Cython/pyximport things I added support for this reload edit-run-cycle,
>> because I cannot imagine to dev without this.
> Let me assure you - it works :)
> for example yesterday, I create a full CRUD-interface for a web-app
> (which is the thing I work on mostly these days) without *once* taking a
> look at the browser. I wrote actions, forms, HTML, and tests along,
> developed the thing ready, asserted certain constraints and error-cases,
> and once finished, fired up the browser - and he saw, it worked!
> Yes, I could have written that code on the fly, hitting F5 every few
> seconds/minutes to see if things work out (instead of just running the
> specific tests through nose) - and once I'd be finished, I didn't have
> anything permanent that ensured the functionality over time.
well in this 1-day example you coded a thing which obviously you
had already done similarly several times. still I guess, you had
some debug session too. some exploration of new things and new
aspects. profiting e.g. particularly from the Python interactive /
interactive debugger, post mortem etc. ..
unless you type so perfect from scratch as that guy in Genesis 1 :-)
>> this is a comfortable quasi religious theory raised often and easily
>> here and there - impracticable and very slow on that fine grained code
>> evolution level however. an interesting issue.
> To me, that's as much as an religious statement often heard by people
> that aren't (really) into test-driven development. By which I personally
> don't mean the variant where one writes tests first, and then code. I
> always develop both in lock-step, sometimes introducing a new feauter
> first in my test as e.g. new arguments, or new calls, and then
> implementing them, but as often the other way round.
> The argument is always a variation of "my problem is to complicated, the
> code-base to interviened to make it possible to test this".
well, nothing against preaching about tests ;-) , unless its too
like with every extreme there is also a threshold where you don't
draw anymore at the bottom line by adding more tests. there are
costs too. other bottle necks ...
its not against test writing for testing/validating/stabilizing
and other indirect high-level benefactions. there are simply other
dimensions too, which are worth a thought or two. the question
about a good reload scheme is more oriented towards the
debugging/interactive/exploration/editing level. things, where
particularly Python opens new dimensions by its superior dynamic
and self-introspective nature.
> I call this a bluff. You might work with a code-base that makes it
> harder than needed to write tests for new functionality. But then, most
> of the time this is a sign of lack of design. Writing with testability
> in mind makes you think twice about how to proper componentize your
> application, clearly separate logic from presentation, validates
> API-design because using the API is immediatly done when writing the
> tests you need, and so forth.
yes, tests writing can also induce a better code modularization.
a good editor, good debugging/reload scheme etc also radiate...
the test runner can be connected to the post mortem
debugger/interactive and so on.
>> "Reload > pychecker/pylint > tests" works most effectively with Python
>> in my opinion.
>> And for GUI-development the difference is max.
>> (min for math algorithms which are well away from data structures/OO)
> As I said, I mainly do web these days. Which can be considered GUIs as
> well. Testing the HTTP-interface is obviously easier & possible, and
> what I described earlier.
> But we also use selenium to test JS-driven interfaces, as now the
> complexity of the interface rises, with all the bells & whistles of
> ajaxiness and whatnot.
(the CRUD approach on 'form handling IO level' as it is typically
more simple regarding tests writing than GUI programming - because
of the atomic operations and straight interface. similar like alg
and I/O testing.
While test writing for a flattery JS/CSS-heavy multi-language
multi-state web GUIs (with subtle user interactions) is perhaps
similar complex than doing it for a desktop GUI app I think.
>> A rule that unit tests are used only near a release or a milestone is
>> healthy in that sense I think.
>> (And a quick edit-(real)run-interact cycle is good for speed)
> Nope, not in my opinion. Making tests an afterthought may well lead to
> them being written carelessly, not capturing corner-cases you
Anyway one can formulate/write tests on each error/problem/design
question which one thinks is worth a test.
A interesting question may be however: if the tests (both: unit
tests and auto code checks) should be _run_ permanently - in order
to lets say have a 'zero test dump status' overall every few
minutes, at the time scale of editing/exploring/debugging ?
I think that one doesn't loose on the savety net effect, but one
wins on overall validation power of the tests, when one _uses_ the
(new and old) tests not too often: more rarely/later/before the
'release'. because after many things are rewired in the code
(incl. test code) for a milestone/release step or, each bump which
arises fresh, lets you think/cure about the network effects and
deeper effect of errors in common, similar contexts etc.
While when one makes the code fit against the 'few artificial
tests' (which are always very/too few!) too fast on the wrong time
scale, its like in that example of quick antibiotica
application/abuse: the cure for the bumps then tend to be too
short sighted. symptom curing. while the clever bugs arise in
having fresh written tests unused for some time is no problem,
because they will induce there own debug session sooner or later ..
> Testing is no silver bullet. But it's a rather mighte sword.. :)
I'd say testing has its place amongst other things and dimensions
Editor: type, browse
Interactive: inspect, try
Debug: inspect, fix
Reload: fix, iterate, explore, clean
Code checks: stabilize
Unit tests: stabilize
Each issue can be improved. effective in overall speed. He saw:
If you have no good editor there is some 1.5 .. 2 x less dev
speed. If you have no Python (Ruby, Groovy...) there is some 1.5
.. 2 x less dev speed. If you have no good Interactive/Debugging
there is some 1.5 .. 2 x less dev speed. If you have no improved
reload scheme there is another 1.5 .. 2 x less dev speed. If you
have no good design scheme there is another 1.5 .. 2 x less dev
speed. If you have no good code checks there is another 1.5 .. 2 x
less dev speed. If you have no good test scheme there is another
1.5 .. 2 x less dev speed. If you have no good bug report scheme
there is another 1.5 .. 2 x less dev speed. ...
A improved reload scheme may even speed up at the center of the
development wheel: iteration. I guess I underrated...
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