I used to favor determinism/repeatability (fixed seed to Random) too,
but I recently changed my mind.
By allowing Random to randomly seed itself, we effectively test a much
much larger space, ie every time we all run the test, it's different.
We can
potentially cast a much larger net than a fixed seed.
This way, if there is a bug lurking, it will eventually be seen by
someone.
Once the bug is discovered (which is 90% of the "challenge"), we can
always run many iterations, test different seeds, etc., to track down
the cause & fix it.
Fixing the bug is the "easy" part; discovering a bug is present is where
we need all the help we can get ;)
Mike
Chris Hostetter wrote:
: It's not repeatable, which is fine (because the test has
randomness, which we
: should leave in there).
Side note: while i agree that test with randomness (ie: do lots of
iterations over randomly selected data) are good to help find weird
edge
casees you might not otherwise think to explicitly code tests for,
i've
found by painful experience that generating the random data using a
Random
object with a hard coded seed is a good practice -- that way you get
the
benefits of hte Random data, but the test is also reproducable.
otherwise you get test failures that that you *think* you understand
the
cause of based on the stack trace, but without knowing exactly what
input
was used, you can't be sure you're fixing the "right" bug.
-Hoss
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