To cite checkr in publications use:

Joe Thorley (2018). checkr: An R package for Assertive Programming. Journal of Open Source Software, 3(23), 624. URL https://doi.org/10.21105/joss.00624

Corresponding BibTeX entry:

  @Article{,
    title = {checkr: {An} {R} package for {Assertive} {Programming}},
    author = {Joe Thorley},
    journal = {Journal of Open Source Software},
    year = {2018},
    volume = {3},
    number = {23},
    pages = {624},
    url = {http://joss.theoj.org/papers/10.21105/joss.00624},
  }