How do you unit test code that relies on randomly generated numbers?

Question

What is the best way to unit test code that relies on you randomly generating data? I found this question on stack overflow but it is a little different. I know that you can use fixtures to mock out something like a database but I think that what I'm trying to do is a little different.

I'm trying to write an adaline neural network. This requires me to randomly generate weights and then the values for the weights are adjusted as more data is presented to the network. How do I unit test something like this? I've started writing tests for the parts that don't rely on random inputs, but I don't know how to handle this part.

Any suggestions would be appreciated.

make a moku-up for the component that generates number so it becomes predictable — Liviu Stirb, Jun 26 '13 at 15:21
@Phylogenesis I'm using the random method in Java's Math class similar to [this](http://stackoverflow.com/a/363732/667440). I'm not providing a seed for random number generation. — j.jerrod.taylor, Jun 26 '13 at 15:37
About ten years ago when I was taking software engineering courses towards an MSCS, I asked that very same question. I was told it would make an excellent master's thesis project. So at the time, it was not an easy question to answer. — Novak, Jun 26 '13 at 17:51
@Novak I'm in graduate school also...but I want to do my thesis project on something else. — j.jerrod.taylor, Jun 26 '13 at 18:13

score 0 · Answer 1 · answered Jun 26 '13 at 15:22

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You could use new Random(seed) to get deterministic random number all the time. Why non-deterministic tests are a problem? Click here to see why

answered Jun 26 '13 at 15:22

Kelvin Ng

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How do you unit test code that relies on randomly generated numbers?

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