Before:
  Save g:ale_warn_about_trailing_whitespace

  let g:ale_warn_about_trailing_whitespace = 1

  runtime ale_linters/python/pydocstyle.vim

After:
  Restore

  call ale#linter#Reset()

  silent file something_else.py

" File sample.py
"    # sample.py file
"
"    def main():
"        """
"        This is a multi-line description that should produce multiple errors to be
"        tested by the handler
"        """
"        return Fales
"
"
"    if __name__ == '__main__':
"        main()
"
" The command to generate the handler input is:
"
"    $ python -m pydocstyle --verbose --source --explain sample.py
"    [...]
"    $

Execute(Basic pydocstyle warnings should be handled):
  AssertEqual
  \ [
  \   {
  \     'lnum': 1,
  \     'col': 1,
  \     'text': 'Missing docstring in public module',
  \     'code': 'D100',
  \     'type': 'W',
  \   },
  \   {
  \     'lnum': 4,
  \     'col': 1,
  \     'text': '1 blank line required between summary line and description (found 0)',
  \     'code': 'D205',
  \     'type': 'W',
  \   },
  \   {
  \     'lnum': 4,
  \     'col': 1,
  \     'text': 'First line should end with a period (not ''e'')',
  \     'code': 'D400',
  \     'type': 'W',
  \   },
  \   {
  \     'lnum': 4,
  \     'col': 1,
  \     'text': 'First line should be in imperative mood; try rephrasing (found ''This'')',
  \     'code': 'D401',
  \     'type': 'W',
  \   },
  \ ],
  \ ale_linters#python#pydocstyle#Handle(bufnr(''), [
  \ 'Checking file ' . fnamemodify(bufname(bufnr('')), ':p') . '.',
  \ ale#Escape(fnamemodify(bufname(bufnr('')), ':t')) . ':1 at module level:',
  \ '        D100: Missing docstring in public module',
  \ '',
  \ '        All modules should normally have docstrings.  [...] all functions and',
  \ '        classes exported by a module should also have docstrings. Public',
  \ '        methods (including the __init__ constructor) should also have',
  \ '        docstrings.',
  \ '        Note: Public (exported) definitions are either those with names listed',
  \ '              in __all__ variable (if present), or those that do not start',
  \ '              with a single underscore.',
  \ '',
  \ '  1: #  2:    3: s  4: a  5: m  6: p  7: l        ...',
  \ '',
  \ '',
  \ ale#Escape(fnamemodify(bufname(bufnr('')), ':t')) . ':4 in public function `main`:',
  \ '        D205: 1 blank line required between summary line and description (found 0)',
  \ '',
  \ '        Multi-line docstrings consist of a summary line just like a one-line',
  \ '        docstring, followed by a blank line, followed by a more elaborate',
  \ '        description. The summary line may be used by automatic indexing tools;',
  \ '        it is important that it fits on one line and is separated from the',
  \ '        rest of the docstring by a blank line.',
  \ '',
  \ '  3: d  4: e  5: f  6:    7: m  8: a  9: i        ...',
  \ '',
  \ '',
  \ ale#Escape(fnamemodify(bufname(bufnr('')), ':t')) . ':4 in public function `main`:',
  \ '        D400: First line should end with a period (not ''e'')',
  \ '',
  \ '        The [first line of a] docstring is a phrase ending in a period.',
  \ '',
  \ '  3: d  4: e  5: f  6:    7: m  8: a  9: i        ...',
  \ '',
  \ '',
  \ ale#Escape(fnamemodify(bufname(bufnr('')), ':t')) . ':4 in public function `main`:',
  \ '        D401: First line should be in imperative mood; try rephrasing (found ''This'')',
  \ '',
  \ '        [Docstring] prescribes the function or method''s effect as a command:',
  \ '        ("Do this", "Return that"), not as a description; e.g. don''t write',
  \ '        "Returns the pathname ...".',
  \ '',
  \ '  3: d  4: e  5: f  6:    7: m  8: a  9: i        ...',
  \ ])

Execute(Handler should handle empty output):
  AssertEqual
  \ [],
  \ ale_linters#python#pydocstyle#Handle(bufnr(''), [])