" NOTE: We use the 'b:' forms below to ensure that we're properly using
" ale#Var()

Given dockerfile:
  #

Before:
  Save g:ale_dockerfile_hadolint_use_docker
  Save g:ale_dockerfile_hadolint_docker_image
  silent! unlet g:ale_dockerfile_hadolint_use_docker
  silent! unlet g:ale_dockerfile_hadolint_docker_image

  " enable loading inside test container
  silent! cd /testplugin
  source ale_linters/dockerfile/hadolint.vim


After:
  Restore
  silent! unlet b:ale_dockerfile_hadolint_use_docker
  silent! unlet b:ale_dockerfile_hadolint_docker_image


Execute(linter honors ..._use_docker correctly):

  " default: never
  AssertEqual
  \ 'hadolint',
  \ ale_linters#dockerfile#hadolint#GetExecutable(bufnr(''))

  " explicit never
  let b:ale_dockerfile_hadolint_use_docker = 'never'
  AssertEqual
  \ 'hadolint',
  \ ale_linters#dockerfile#hadolint#GetExecutable(bufnr(''))

  let b:ale_dockerfile_hadolint_use_docker = 'always'
  AssertEqual
  \ 'docker',
  \ ale_linters#dockerfile#hadolint#GetExecutable(bufnr(''))

  " hadolint if present, otherwise docker
  let command = 'docker'
  if executable('hadolint')
    let command = 'hadolint'
  endif

  let b:ale_dockerfile_hadolint_use_docker = 'yes'
  AssertEqual
  \ command,
  \ ale_linters#dockerfile#hadolint#GetExecutable(bufnr(''))


Execute(command is correct when using docker):
  let b:ale_dockerfile_hadolint_use_docker = 'always'

  AssertEqual
  \ "docker run --rm -i lukasmartinelli/hadolint",
  \ ale_linters#dockerfile#hadolint#GetCommand(bufnr(''))


Execute(command is correct when not docker):
  let b:ale_dockerfile_hadolint_use_docker = 'never'

  AssertEqual
  \ "hadolint -",
  \ ale_linters#dockerfile#hadolint#GetCommand(bufnr(''))

" fin...