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Re: [TDD] Testing a class which utilizes randomness

Nikola Novak
 

Hello!

Thanks everyone for your replies. Like I said, I'm not testing the RNG (or RSG in this case), but rather the algorithm which deals with duplicates.
I'll go with what David and John suggested, writing a class to generate unique random strings and injecting a random string generator.
Interesting how a TDD approach resulted in code being organized properly. If I hadn't used it, I'd probably have written a method that used an embedded random string generator and would never have given the problem a second thought.

Thanks for the help,
Nikola



On Fri, Apr 4, 2014 at 8:52 PM, Steven Gordon <sgordonphd@...> wrote:
?

Agreed.

Already suggested that the" history" object is what needs to be TDD-ed.

The fact that randomness is not a good candidate for TDD-ing is just an interesting side-note.


On Fri, Apr 4, 2014 at 11:50 AM, Ron Jeffries <ronjeffries@...> wrote:
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I¡¯m pretty sure OP is trying to learn how to TDD, not how to create really great random strings.

:)
R

On Apr 4, 2014, at 2:48 PM, Steven Gordon <sgordonphd@...> wrote:

This project is presumably using an RNG rather than coding one.

The criteria that matters would be whether the strings being generated (using an RNG) is sufficiently random, not whether the sequence of numbers that are being used to generate those strings are sufficiently random.

It is quite possible for the RNG to be random enough, but the strings to not be. ?For example, the long term behavior of the random number generator could always create a nice random distribution on bins, but that subsequences are not as random. If each string would be created by a subsequence rather than individual number, then they would not be random enough.

It could make a difference whether or not the size of the character set is prime.


Ron Jeffries
I know we always like to say it'll be easier to do it now than it
will be to do it later. Not likely. I plan to be smarter later than
I am now, so I think it'll be just as easy later, maybe even easier.
Why pay now when we can pay later?



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