Before:
  call ale#assert#SetUpLinterTest('r', 'lintr')

After:
  call ale#assert#TearDownLinterTest()

Execute(The default lintr command should be correct):
  AssertLinter 'Rscript',
  \   ale#path#CdString(ale#Escape(getcwd()))
  \   . 'Rscript --vanilla -e '
  \   . ale#Escape('suppressPackageStartupMessages(library(lintr));'
  \   .            'lint(cache = FALSE, commandArgs(TRUE), '
  \   .            'with_defaults())')
  \   . ' %t'

Execute(The lintr options should be configurable):
  let b:ale_r_lintr_options = 'with_defaults(object_usage_linter = NULL)'

  AssertLinter 'Rscript',
  \   ale#path#CdString(ale#Escape(getcwd()))
  \   . 'Rscript --vanilla -e '
  \   . ale#Escape('suppressPackageStartupMessages(library(lintr));'
  \   .            'lint(cache = FALSE, commandArgs(TRUE), '
  \   .            'with_defaults(object_usage_linter = NULL))')
  \   . ' %t'

Execute(If the lint_package flag is set, lintr::lint_package should be called):
  let b:ale_r_lintr_lint_package = 1

  AssertLinter 'Rscript',
  \   ale#path#CdString(ale#Escape(getcwd()))
  \   . 'Rscript --vanilla -e '
  \   . ale#Escape('suppressPackageStartupMessages(library(lintr));'
  \   .            'lint_package(cache = FALSE, '
  \   .            'linters = with_defaults())')
  \   . ' %t'