Before:
  runtime ale_linters/sass/sasslint.vim

  call ale#test#SetDirectory('/testplugin/test/command_callback')
  call ale#test#SetFilename('test.sass')

After:
  Restore

  call ale#test#RestoreDirectory()
  call ale#linter#Reset()

Execute(The default sasslint command should be correct):
  AssertEqual
  \ 'cd ' . ale#Escape(expand('%:p:h')) . ' && '
  \   . ale#Escape('sass-lint') . ' -v -q -f compact %t',
  \ ale_linters#sass#sasslint#GetCommand(bufnr(''))