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

After:
  call ale#test#RestoreDirectory()

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#handlers#sasslint#GetCommand(bufnr(''))