Before:
  Save g:ale_nix_alejandra_executable
  Save g:ale_nix_alejandra_options

After:
  Restore

Execute(The alejandra callback should return the correct default values):
  AssertEqual
  \ {
  \   'command': ale#Escape('alejandra') . ' -- -'
  \ },
  \ ale#fixers#alejandra#Fix(bufnr(''))

Execute(The alejandra executable and options should be configurable):
  let g:ale_nix_alejandra_executable = '/path/to/alejandra'
  let g:ale_nix_alejandra_options = '-q'

  AssertEqual
  \ {
  \   'command': ale#Escape('/path/to/alejandra')
  \     . ' -q -- -',
  \ },
  \ ale#fixers#alejandra#Fix(bufnr(''))