CRAN Parallelization

CRAN does not allow packages to use more than 2 cores when running testthat.R. The test on Debian then returns an error like this.

* checking tests ... [54s/18s] NOTE
  Running ‘testthat.R’ [53s/18s]
Running R code in ‘testthat.R’ had CPU time 3 times elapsed time

Since CRAN does not say which test takes too long, this code can help to find the problem.

files = list.files("tests/testthat", "test_", full.names = TRUE)

for (file in files) {

  time = system.time(test_file(file))
  ratio = time[1] / time[3]
  if (ratio > 2) {
    print(time)
    stopf("Test file %s had CPU time %f times elapsed time", file, ratio)
  }
}