Before:
  runtime ale_linters/perl/perlcritic.vim

After:
  call ale#linter#Reset()

Execute(The Perl::Critic handler should create all issues as warnings):
  AssertEqual
  \  [
  \    {
  \      'lnum': '21',
  \      'col': '17',
  \      'text': 'Regular expression without "/m" flag',
  \      'type': 'W',
  \    }
  \  ],
  \  ale_linters#perl#perlcritic#Handle(99, [
  \      '21:17 Regular expression without "/m" flag'
  \  ])