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

  runtime ale_linters/php/phpstan.vim

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

Execute(Output without errors should be parsed correctly):
  call ale#test#SetFilename('phpstan-test-files/foo/test.php')

  AssertEqual
  \ [],
  \ ale_linters#php#phpstan#Handle(bufnr(''), [
  \ '{"totals":{"errors":0,"file_errors":0},"files":[],"errors":[]}',
  \ ])

Execute(Output with some errors should be parsed correctly):
  call ale#test#SetFilename('phpstan-test-files/foo/test.php')

  AssertEqual
  \ [
  \   {
  \     'lnum': 9,
  \     'text': 'Call to method format() on an unknown class DateTimeImutable.',
  \     'type': 'E'
  \   },
  \   {
  \     'lnum': 16,
  \     'text': 'Sample message.',
  \     'type': 'E'
  \   },
  \   {
  \     'lnum': 192,
  \     'text': 'Invalid command testCommand.',
  \     'type': 'E'
  \   }
  \ ],
  \ ale_linters#php#phpstan#Handle(bufnr(''), [json_encode(
  \ {
  \     "totals":{"errors": 0, "file_errors": 11},
  \     "files":{expand('%:p'): {"errors": 3, "messages": [
  \         {"message": "Call to method format() on an unknown class DateTimeImutable.", "line":9},
  \         {"message": "Sample message.", "line":16},
  \         {"message": "Invalid command testCommand.", "line": 192}
  \     ]}}
  \ },
  \)])