def METHOD_NAME(self):
    path = self._create_file(
        'one.example.com ssh-rsa AAAAetc\n'
        'two.example.com ssh-rsa BBBBetc\n'
    )
    key = 'one.example.com ssh-rsa AAAAetc\n'
    diff = compute_diff(path, found_line=1, replace_or_add=False, state='present', key=key)
    self.assertEqual(diff, {
        'before_header': path,
        'after_header': path,
        'before': 'one.example.com ssh-rsa AAAAetc\ntwo.example.com ssh-rsa BBBBetc\n',
        'after': 'one.example.com ssh-rsa AAAAetc\ntwo.example.com ssh-rsa BBBBetc\n',
    })