Before:
  call ale#assert#SetUpFixerTest('markdown', 'rumdl')

After:
  call ale#assert#TearDownFixerTest()

Execute:
  AssertFixer {
  \ 'command': ale#Escape('rumdl') . ' fmt - --silent',
  \}

Execute:
  let g:ale_markdown_rumdl_executable = 'rumdl_custom'

  AssertFixer {
  \ 'command': ale#Escape('rumdl_custom') . ' fmt - --silent',
  \}

Execute:
  let g:ale_markdown_rumdl_fmt_options = ''

  AssertFixer {
  \ 'command': ale#Escape('rumdl') . ' fmt -',
  \}