rcmdcheck: Run 'R CMD check' from 'R' and Capture Results

#' rcmdcheck configuration
#'
#' Options take precedence over environment variables. E.g. if both
#' the `RCMDCHECK_NUM_COLORS` environment variables and the
#' `rcmdcheck.num_colors` option are set, then the latter is used.
#'
#' rcmdcheck uses the cli package for much of its output, so you can
#' configure the output via cli, see [cli::cli-config].
#'
#' Package configration is defined in the `DESCRIPTION` file of the checked
#' package. E.g.:
#' ```
#' Config/build/clean-inst-doc: FALSE
#' ```
#'
#' # Environment variables
#'
#' * `R_PROFILE_USER`: standard R environment variable to configure the
#'   path to the user level R profile. See [base::R_PROFILE_USER].
#'
#' * `RCMDCHECK_BASE_URL`: URL to the root of the CRAN check web page.
#'   You can use this to select an alternative CRAN mirror. Defaults to
#'   `https://cran.r-project.org/web/checks/`.
#'
#' * `RCMDCHECK_DETAILS_URL`: URL to the root of the CRAN check output
#'   page. Defaults to `https://www.r-project.org/nosvn/R.check/`.
#'
#' * `RCMDCHECK_ERROR_ON`: the default value for the `error_on` argument
#'   of [rcmdcheck()].
#'
#' * `RCMDCHECK_FLAVOURS_URL` URL to the CRAN check flavours page.
#'   You can use this to select an alternative CRAN mirror. Defaults to
#'   `https://cran.r-project.org/web/checks/check_flavors.html`.
#'
#' * `RCMDCHECK_NUM_COLORS`: the number of ANSI colors to use in the output.
#'   It can be used to override the number of colors detected or configured
#'   by the cli package. See [cli::num_ansi_colors()]. This configuration
#'   is only used for the output of rcmdcheck and it does not affect the
#'   examples and test cases (and other code) of the checked package.
#'   It not set, then the default of cli is uesed. The corresponding
#'   option is `rcmdcheck.num_colors`.
#'
#' * `RCMDCHECK_TIMESTAMP_LIMIT`: lower limit is seconds, above which
#'   rcmdcheck adds time stamps to the individual check steps. It may be
#'   fractional. Defaults to 1/3 of a second. The corresponding option is
#'   `rcmdcheck.timestamp_limit`.
#'
#' * `RCMDCHECK_USE_RSTUDIO_PANDOC`: Flag (`true` or `false`). If `true`,
#'   then rcmdcheck _always_ puts RStudio's pandoc (if available) on the
#'   path. If `false`, then it _never_ does that. If not set, or set to a
#'   different value, then pandoc is put on the path only if it is not
#'   already available. RStudio's pandoc is detected via an `RSTUDIO_PANDOC`
#'   environment variable.
#'
#' * `RCMDCHECK_LOAD_CHECK_ENV`: you can use this environment variable
#'   suppress loading environment variables from the `tools/check.env` file.
#'   See [rcmdcheck()] for details.
#'
#' * `RSTUDIO_PANDOC`: if set, rcmdcheck adds this environment variable
#'   to the PATH if pandoc is not on the PATH already. It is usually set
#'   in RStudio. See also the `RCMDCHECK_USE_RSTUDIO_PANDOC` environment
#'   variable.
#'
#' # Options
#'
#' * `rcmdcheck.num_colors`: the number of ANSI colors to use in the output.
#'   It can be used to override the number of colors detected or configured
#'   by the cli package. See [cli::num_ansi_colors()]. This configuration
#'   is only used for the output of rcmdcheck and it does not affect the
#'   examples and test cases (and other code) of the checked package.
#'   It not set, then the default of cli is uesed. The corresponding
#'   environment variable is `RCMDCHECK_NUM_COLORS`.
#'
#' * `rcmdcheck.test_output`: Flag (`TRUE` or `FALSE`), whether
#'   [print.rcmdcheck()] should print the full test output if there are
#'   no test failures. If some tests fail, then only the failures are
#'   printed, independently of this option.
#'
#' * `rcmdcheck.timestamp_limit`: lower limit is seconds, above which
#'   rcmdcheck adds time stamps to the individual check steps. It may be
#'   fractional. Defaults to 1/3 of a second. The corresponding environment
#'   variable is `RCMDCHECK_TIMESTAMP_LIMIT`.
#'
#' # Package configuration:
#'
#' * `Config/build/clean-inst-doc`: Flag (`TRUE` or `FALSE`) to
#'   specify if the `inst/doc` directory should be cleaned up when
#'   building a package directory. If not specified, then `NULL` is used.
#'   See the `clean_doc` option of [pkgbuild::build()] for more details.
#'
#' @name rcmdcheck-config
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