[Gridflow-dev] test suite

[Mathieu Bouchard]

GridFlow could afford a better test suite. base/test.rb should be replaced
by something more appropriate i'm thinking something that would look like:

[#expect, send 1 2 3, get 4 5 6] X [# + 3]

so [#expect] would be a new control object destined to do quality 
assurance. actually there's already one sort of like that in
base/test.rb, but it's not usable outside of Ruby.

there could be a [, radius 42] option so that instead of using exact
equality like [# ==] -> [#ravel] -> [#fold &] it would use euclidean
distance [# sq-] -> [#ravel] -> [#fold +] -> [# sqrt] as is used in
statistics and acoustics to evaluate the energy or the RMS amplitude.
Alternatively it could use manhattan distance [# abs-] -> [#ravel] ->
[#fold +] which is what used in chemistry labs to compute error
propagation. Which one to use could be controlled by a message "norm 2"  
and "norm 1" respectively.

This "radius" extension to the normal Extreme Programming testing is 
necessary to address two issues:

1. the usual equality testing can't be used successfully with floats
   because slight deviations in computation can be obtained quite easily.
   For example you just can't rely on (A+B)+C==A+(B+C), ever, although the
   error radius could usually be about 16 million times smaller than the
   involved numbers.

2. similar rounding issues can occur in integer math and that it can be
   sometimes okay for one high-level effect to yield slightly different
   numbers as long as it appears roughly the same on-screen.

Other automated testing patterns should be developed to address issues 
such as testing GUI objects like [display] [#peephole] [#edit].

Possibly that it's time to introduce semi-automated testing, in which the
part that is fully automatable gets automated, but is interleaved with
documentation taking the tester by the hand, so that the tester doesn't
have to think too much and doesn't forget what it is s/he is supposed to
test; this makes testing time shorter thus tests become more affordable.

What do you think?

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