Before:
  runtime! ale_linters/markdown/textlint.vim

After:
  call ale#linter#Reset()

Execute(textlint handler should handle errors output):
  AssertEqual
  \ [
  \   {
  \     'lnum': 16,
  \     'col': 50,
  \     'text': 'Found possibly misspelled word "NeoVim".',
  \     'type': 'W',
  \     'code': 'preset-japanese/no-doubled-joshi',
  \   },
  \ ],
  \ ale#handlers#textlint#HandleTextlintOutput(bufnr(''), [
  \   '[',
  \   '  {',
  \   '    "filePath": "test.md",',
  \   '    "messages": [',
  \   '      {',
  \   '        "type": "lint",',
  \   '        "ruleId": "preset-japanese/no-doubled-joshi",',
  \   '        "index": 1332,',
  \   '        "line": 16,',
  \   '        "column": 50,',
  \   '        "severity": 2,',
  \   '        "message": "Found possibly misspelled word \"NeoVim\"."',
  \   '      }',
  \   '    ]',
  \   '  }',
  \   ']',
  \ ])

Execute(textlint handler should no error output):
  AssertEqual
  \ [],
  \ ale#handlers#textlint#HandleTextlintOutput(bufnr(''), [])