To cite package ‘exampletestr’ in publications use:

  Nolan R, Padilla-Parra S (2017). “exampletestr - An easy start to
  unit testing R packages.” _Wellcome Open Research_, *2*, 31.
  doi:10.12688/wellcomeopenres.11635.2
  <https://doi.org/10.12688/wellcomeopenres.11635.2>.

A BibTeX entry for LaTeX users is

  @Article{Nolan2017,
    doi = {10.12688/wellcomeopenres.11635.2},
    year = {2017},
    month = {jun},
    publisher = {F1000 Research,  Ltd.},
    volume = {2},
    pages = {31},
    author = {Rory Nolan and Sergi Padilla-Parra},
    title = {exampletestr - An easy start to unit testing R packages},
    journal = {Wellcome Open Research},
  }