Testing of distributions

[pitdicker]

We should add some testing for distributions. Unfortunately since distribution samples are random, this is inherently difficult. Original issue dhardy#72.

See for some direction rust-lang/rust#10084, and the random-tests.

[vks]

Also see #290.

[dhardy]

@vks has some plans for histogram-based testing, though possibly only after PDFs are added.

Separately, we should add some tests of value-stability.

[vks]

@vks has some plans for histogram-based testing, though possibly only after PDFs are added.

See tests/uniformity.rs, which could be generalized to arbitrary distributions (with given PDFs).

[dhardy]

@vks could I interest you (or potentially someone else) in adding at utility to rand_distr (perhaps an example) which plots histograms of each distribution from actual samples (not PDFs)? This would at least let us eye-ball that distributions are doing roughly the right thing.

[vks]

I was thinking about using sparklines for that. I'm interested, but I can't make promises that I'll get to it before the end of the year.

[vks]

Resolving this issue was started in #1121, more work is needed to extend it to the other distributions.