New Distribution Testing Infastructure

[JacobHass8]

Currently, the new helper function, test_invalid_support, only ensures that a domain error is thrown if the cdf, pdf, logcdf, logpdf or quantile is sampled outside the support of the distribution. I think there are still edge cases that need to be addressed. Here are my following thoughts

• How should the cdf/pdf behave when sampled at +/- infinity? The current testing only checks for distributions with finite support. If the support is infinite should I check that the pdf and cdf evaluate properly at +/- infinity?
• The current function relies on distributions having default arguments. Hopefully this is the case and doesn't get me in trouble.
• I'm unsure how to test incorrect construction of a distribution. I think that the best way would be to define something similar to the support function but here we define a vector of pairs that list each parameter's space.

I've deleted some tests that I previously added for the arcsine distribution just to see if I am getting the same code coverage as before (100%).

Here's the code coverage report.

[jzmaddock]

Thanks for this,

How should the cdf/pdf behave when sampled at +/- infinity? The current testing only checks for distributions with finite support. If the support is infinite should I check that the pdf and cdf evaluate properly at +/- infinity?

I guess so, and actually we can check the values are correct too I think? PDF should be zero at +-INF and CDF should be zero at -INF and 1 at +INF.

[codecov]

Codecov Report

❌ Patch coverage is 97.14286% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 95.60%. Comparing base (7a0975e) to head (4a08e16).
⚠️ Report is 1 commits behind head on develop.

Files with missing lines	Patch %	Lines
test/test_dist_helpers.hpp	97.05%	2 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1400      +/-   ##
===========================================
- Coverage    95.61%   95.60%   -0.01%     
===========================================
  Files          825      826       +1     
  Lines        68487    68506      +19     
===========================================
+ Hits         65481    65498      +17     
- Misses        3006     3008       +2     

Files with missing lines	Coverage Δ
test/test_arcsine.cpp	99.12% <100.00%> (-0.13%)	⬇️
test/test_bernoulli.cpp	100.00% <100.00%> (ø)
test/test_dist_helpers.hpp	97.05% <97.05%> (ø)

... and 2 files with indirect coverage changes

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[JacobHass8]

I'm trying to write a function to test bad constructors. My idea was to pass in a vector of vectors where each element is a vector of invalid parameters. However, it's not working as I intended and I have no clue why.

I'm first trying to do this for the arcsine distribution. I began by defining a new constructor from a vector

BOOST_MATH_GPU_ENABLED arcsine_distribution(std::vector<RealType> params) : arcsine_distribution(params[0], params[1]) {}

which just unpacks the vector and calls the original constructor. Then in test_arcsine.hpp, I have

std::vector<std::vector<RealType> > invalid_params = {{1, 0}, // x_min > x_max
                                                      {1, -1}}; 
test_invalid_parameters<arcsine_distribution, RealType>(invalid_params);

The function test_invalid_parameters is defined as

template <template <typename...> typename Distribution, class Real>
void test_invalid_parameters(std::vector<std::vector<Real> > invalid_parameters)
{
    typedef Distribution<Real> dist;

    std::vector<Real> params;
    for (unsigned i=0; i<invalid_parameters.size(); i++)
    {
        params = invalid_parameters[i];
        BOOST_CHECK_THROW(dist(params), std::domain_error); // This should throw an error, but doesn't! 
        BOOST_CHECK_THROW(dist x(params), std::domain_error); // This throws a domain_error
        BOOST_CHECK_THROW(boost::math::pdf(dist(params), 0.5), std::domain_error); // This also throws a domain_error
    }
}

I don't understand why dist(params) doesn't throw an error but dist x(params) does. @jzmaddock do you have any thoughts? I'm still new to c++ and this is getting beyond my understanding.