Before:
  call ale#test#SetDirectory('/testplugin/test/handler')
  cd ..

  runtime ale_linters/ruby/packwerk.vim

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

Execute(The packwerk handler should parse lines correctly):
  call ale#test#SetFilename('test-files/ruby/valid_rails_app/app/models/thing.rb')

  AssertEqual
  \ [
  \     {
  \         'lnum': 36,
  \         'col': 100,
  \         'text': 'Dependency violation: ::Edi::Source belongs to ''edi'', but ''billing'' does not specify a dependency on ''edi''.',
  \     }
  \ ],
  \ ale_linters#ruby#packwerk#Handle(bufnr(''), [
  \   '/Users/JaneDoe/src/github.com/sample-project/billing/app/jobs/document_processing_job.rb:36:100',
  \   'Dependency violation: ::Edi::Source belongs to ''edi'', but ''billing'' does not specify a dependency on ''edi''.',
  \   'Are we missing an abstraction?',
  \   'Is the code making the reference, and the referenced constant, in the right packages?',
  \   '',
  \   'Inference details: ''Edi::Source'' refers to ::Edi::Source which seems to be defined in edi/app/models/edi/source.rb.',
  \ ])