# a wrapper around testthat::test_that(), which also tries
# to confirm that the test hasn't mutated any global state
test_that <- function(desc, code) {

  # skip tests when run on CRAN's macOS machine
  cran <- !interactive() && !identical(Sys.getenv("NOT_CRAN"), "true")
  testthat::skip_if(cran && renv_platform_macos())

  # record global state before test execution
  before <- renv_test_state(cran)

  # run the test
  call <- sys.call()
  call[[1L]] <- quote(testthat::test_that)
  withCallingHandlers(
    eval(call, envir = parent.frame()),
    condition = function(cnd) {
      message <- conditionMessage(cnd)
      if (any(grepl("SSL connect error", message)))
        skip(message)
    }
  )

  # record global state after test execution
  after <- renv_test_state(cran)

  # check for unexpected changes
  diffs <- waldo::compare(before, after)
  if (length(diffs)) {
    fdiffs <- paste(format(diffs), collapse = "\n\n")
    stopf("Test '%s' has modified global state:\n%s\n", desc, fdiffs)
  }

}

renv_test_state <- function(cran) {

  repopath <- renv_tests_repopath()
  userpath <- file.path(renv_bootstrap_user_dir(), "library")

  opts <- options()
  opts <- opts[grep("^diffobj", names(opts), invert = TRUE)]
  opts$ambiguousMethodSelection <- NULL
  opts$restart <- NULL
  opts$repos[opts$repos == "@CRAN@"] <- "https://cloud.r-project.org"
  opts$mc.cores <- NULL
  opts <- opts[csort(names(opts))]

  envvars <- as.list(Sys.getenv())
  envvars <- envvars[grep("^RENV_DEFAULT_", names(envvars), invert = TRUE)]
  envvars <- envvars[grep("^R_PACKRAT_", names(envvars), invert = TRUE)]
  envvars <- envvars[grep("^_R_", names(envvars), invert = TRUE)]
  envvars <- envvars[grep("^CALLR_", names(envvars), invert = TRUE)]
  envvars$RETICULATE_MINICONDA_PYTHON_ENVPATH <- NULL
  envvars$OMP_NUM_THREADS <- NULL
  envvars$OPENBLAS <- NULL
  envvars <- envvars[csort(names(envvars))]

  list(
    libpaths    = if (!cran) .libPaths(),
    connections = getAllConnections(),
    options     = opts,
    repofiles   = list.files(repopath, all.files = TRUE, no.. = TRUE),
    userfiles   = list.files(userpath, all.files = TRUE, no.. = TRUE),
    envvars     = envvars
  )

}