knitr, rmarkdown, testthat, dplyr, ggplot2, gridExtra,
gtools, tidyr
knitr, rmarkdown, testthat (>= 3.0.0), dplyr, ggplot2,
gridExtra, gtools, tidyr
knitr, rmarkdown, testthat (>= 3.0.0), dplyr, ggplot2,
gridExtra, gtools, tidyr, ordinal