如何断言password_length的范围

Question

User.password_length给了我11..256，我该怎么断言

  it do
    expect(User.password_length).to be_between(11, 256)
  end

但我得到了这个

Failure/Error: expect(User.password_length).to be_between(11, 256)
       expected 11..256 to be between 11 and 256 (inclusive), but it does not respond to `<=` and `>=`
     # ./spec/models/user_spec.rb:45:in `block (2 levels) in <top (required)>'
     # -e:1:in `<main>'

我不明白什么不响应＆lt; =和＆gt; =