Before:
  Save g:ale_opa_fmt_executable
  Save g:ale_opa_fmt_options

  " Use an invalid global executable, so we don't match it.
  let g:ale_opa_fmt_executable = 'xxxinvalid'
  let g:ale_opa_fmt_options = ''

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

After:
  Restore

  call ale#test#RestoreDirectory()

Execute(The opa fmt callback should return the correct default values):

  AssertEqual
  \ {
  \   'command': ale#Escape('xxxinvalid') . ' fmt',
  \ },
  \ ale#fixers#opafmt#Fix(bufnr(''))

Execute(The opa fmt callback should include custom options):
  let g:ale_opa_fmt_options = "--list"

  AssertEqual
  \ {
  \   'command': ale#Escape('xxxinvalid')
  \     . ' fmt'
  \     . ' ' . g:ale_opa_fmt_options
  \ },
  \ ale#fixers#opafmt#Fix(bufnr(''))