hedgehog (version 0.1)

hedgehog: Property based testing in R

Description

Hedgehog is a modern property based testing system in the spirit of QuickCheck, originally written in Haskell, but now also available in R.

Options

- `hedgehog.tests`: Number of tests to run in each property (Default: `100`).

- `hedgehog.size`: Maximum size parameter to pass to generators (Default: `50`).

- `hedgehog.shrinks`: Maximum number of shrinks to search for (Default: `100`).

- `hedgehog.discards`: Maximum number of discards permitted within a property test before failure (Default: `100`).

Details

Software testing is critical when we want to distribute our work, but unit testing only covers examples we have thought of.

With hedgehog (integrated into testthat), we can instead test properties which our programs and functions should have, and allow automatic generation of tests, which cover more that we could imagine.

One of the key benefits of Hedgehog is integrated shrinking of counterexamples, which allows one to quickly find the cause of bugs, given salient examples when incorrect behaviour occurs.

References

Campbell, H (2017). hedgehog: Property based testing in R The R Journal under submission.

https://github.com/hedgehogqa/r-hedgehog

Examples

# NOT RUN {
library(hedgehog)
test_that( "Reverse and concatenate symmetry",
  forall( list( as = gen.c( gen.element(1:100) )
              , bs = gen.c( gen.element(1:100) ))
        , function( as, bs )
            expect_identical ( rev(c(as, bs)), c(rev(bs), rev(as)))
  )
)
# }