refactor(tests): test Bernstein function in separate contexts

[hsloot]

Checklist

• [x] R CMD CHECK successful
• [x] tests included
• [x] documentation included or updated
• [x] commit messages follow commit guidelines

[codecov[bot]]

Codecov Report

Base: 90.57% // Head: 90.92% // Increases project coverage by +0.35% :tada:

Coverage data is based on head (496308c) compared to base (50f8db5). Patch coverage: 100.00% of modified lines in pull request are covered.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #110 +/- ## ========================================== + Coverage 90.57% 90.92% +0.35% ========================================== Files 43 43 Lines 1421 1433 +12 ========================================== + Hits 1287 1303 +16 + Misses 134 130 -4 ``` | [Impacted Files](https://codecov.io/gh/hsloot/rmo/pull/110?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Henrik+Sloot) | Coverage Δ | | |---|---|---| | [R/s4-AlphaStableBernsteinFunction.R](https://codecov.io/gh/hsloot/rmo/pull/110?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Henrik+Sloot#diff-Ui9zNC1BbHBoYVN0YWJsZUJlcm5zdGVpbkZ1bmN0aW9uLlI=) | `80.00% <100.00%> (+1.73%)` | :arrow_up: | | [R/s4-BernsteinFunction.R](https://codecov.io/gh/hsloot/rmo/pull/110?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Henrik+Sloot#diff-Ui9zNC1CZXJuc3RlaW5GdW5jdGlvbi5S) | `100.00% <100.00%> (ø)` | | | [R/s4-ExponentialBernsteinFunction.R](https://codecov.io/gh/hsloot/rmo/pull/110?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Henrik+Sloot#diff-Ui9zNC1FeHBvbmVudGlhbEJlcm5zdGVpbkZ1bmN0aW9uLlI=) | `80.00% <100.00%> (+1.73%)` | :arrow_up: | | [R/s4-GammaBernsteinFunction.R](https://codecov.io/gh/hsloot/rmo/pull/110?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Henrik+Sloot#diff-Ui9zNC1HYW1tYUJlcm5zdGVpbkZ1bmN0aW9uLlI=) | `80.00% <100.00%> (+1.73%)` | :arrow_up: | | [R/s4-InverseGaussianBernsteinFunction.R](https://codecov.io/gh/hsloot/rmo/pull/110?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Henrik+Sloot#diff-Ui9zNC1JbnZlcnNlR2F1c3NpYW5CZXJuc3RlaW5GdW5jdGlvbi5S) | `80.00% <100.00%> (+1.73%)` | :arrow_up: | | [R/s4-ParetoBernsteinFunction.R](https://codecov.io/gh/hsloot/rmo/pull/110?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Henrik+Sloot#diff-Ui9zNC1QYXJldG9CZXJuc3RlaW5GdW5jdGlvbi5S) | `76.00% <100.00%> (+2.08%)` | :arrow_up: | | [R/s4-PoissonBernsteinFunction.R](https://codecov.io/gh/hsloot/rmo/pull/110?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Henrik+Sloot#diff-Ui9zNC1Qb2lzc29uQmVybnN0ZWluRnVuY3Rpb24uUg==) | `75.00% <100.00%> (+2.77%)` | :arrow_up: | | [...molib/random/univariate/bernoulli\_distribution.hpp](https://codecov.io/gh/hsloot/rmo/pull/110?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Henrik+Sloot#diff-aW5zdC9pbmNsdWRlL3Jtb2xpYi9yYW5kb20vdW5pdmFyaWF0ZS9iZXJub3VsbGlfZGlzdHJpYnV0aW9uLmhwcA==) | `97.22% <0.00%> (+2.77%)` | :arrow_up: | | [R/s4-ConvexCombinationOfBernsteinFunctions.R](https://codecov.io/gh/hsloot/rmo/pull/110?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Henrik+Sloot#diff-Ui9zNC1Db252ZXhDb21iaW5hdGlvbk9mQmVybnN0ZWluRnVuY3Rpb25zLlI=) | `62.50% <0.00%> (+12.50%)` | :arrow_up: | Help us with your feedback. Take ten seconds to tell us [how you rate us](https://about.codecov.io/nps?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Henrik+Sloot). Have a feature suggestion? [Share it here.](https://app.codecov.io/gh/feedback/?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=Henrik+Sloot)

:umbrella: View full report at Codecov.
:loudspeaker: Do you have feedback about the report comment? Let us know in this issue.