NameError: undefined local variable or method `session' for #<UserTest:0x0000000658b5c8>

错误发生在下面的log_in_as方法中的else块中：

test_helper.rb中

...

def log_in_as(user,options = {})
  password = options[:password] || 'password'
  remember_me = options[:remember_me] || '1'

  if integration_test?
    post login_path,session: { email: user.email,password: password,remember_me: remember_me }
  else
    session[:user_id] = user.id
  end
end

我在用户测试中调用log_in_as;这两个测试都失败了.

user_test.rb

require 'test_helper'
...
test "login with remembering" do
  log_in_as(@user,remember_me: '1')
  assert_not_nil cookies['remember_token']
end

test "login without remembering" do
  log_in_as(@user,remember_me: '0')
  assert_nil cookies['remember_token']
end
...

当我从帮助程序中删除该行代码时,会抛出一个错误,指出cookie无法识别.这是什么问题？