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

After:
  Restore

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

Execute(The default command should be correct):
  AssertEqual
  \ 'protoc' . ' -I ' . ale#Escape(getcwd()) . ' --lint_out=. ' . '%s',
  \ ale_linters#proto#protoc_gen_lint#GetCommand(bufnr(''))