Before:
  Save g:ale_purescript_purty_executable

  " Use an invalid global executable, so we don't match it.
  let g:ale_purescript_purty_executable = 'my-special-purty'

  call ale#test#SetDirectory('/testplugin/test/fixers')

After:
  Restore

  call ale#test#RestoreDirectory()

Execute(The purty callback should return the correct options):
  call ale#test#SetFilename('../purescript_files/testfile.purs')

  AssertEqual
  \ {
  \   'command': ale#Escape('my-special-purty')
  \     . ' --write'
  \     . ' %t',
  \   'read_temporary_file': 1,
  \ },
  \ ale#fixers#purty#Fix(bufnr(''))