ruby-on-rails - 在 Rails 中将 Guard 从 1.1 升级到 2.1.1 后，它无法识别路线

Question

在升级之前，一切正常。但升级后，它给出了这个错误：

AuthenticationPages
  sign in page
    example at ./spec/requests/authentication_pages_spec.rb:9 (FAILED - 1)

Failures:

  1) AuthenticationPages sign in page
     Failure/Error: before { visit signin_path }
     NameError:
       undefined local variable or method `signin_path' for #<RSpec::Core::ExampleGroup::Nested_2::Nested_1:0x00000003f57488>
     # ./spec/requests/authentication_pages_spec.rb:7:in `block (3 levels) in <top (required)>'
     # -e:1:in `<main>'

Finished in 0.00079 seconds
1 example, 1 failure

Failed examples:

rspec ./spec/requests/authentication_pages_spec.rb:9 # AuthenticationPages sign in page

我怎样才能解决这个问题？