我正在尝试做这样的事情：
describe 'hi' do
it 'should render the home page' do
visit '/'
page.driver.response.status.should eql 200
page.driver.response.content_type.should eql 'text/html'
doc = Nokogiri::HTML(page.driver.response.body)
div = doc.css('div#nav')
div.length.should_not eql 0
end
end
没有这一行，一切都按预期工作：
div.length.should_not eql 0
出现该行，我收到此错误：
<main>:659:in `method_missing': wrong number of arguments (1 for 2) (ArgumentError)
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/metadata.rb:78:in `flatten'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/metadata.rb:78:in `full_description_for'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/metadata.rb:23:in `[]'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/metadata.rb:51:in `full_description_for'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/metadata.rb:23:in `[]'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/example.rb:13:in `block (2 levels) in delegate_to_metadata'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/formatters/base_text_formatter.rb:164:in `dump_failure'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/formatters/base_text_formatter.rb:19:in `block in dump_failures'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/formatters/base_text_formatter.rb:17:in `each'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/formatters/base_text_formatter.rb:17:in `each_with_index'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/formatters/base_text_formatter.rb:17:in `dump_failures'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/reporter.rb:74:in `block in notify'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/reporter.rb:73:in `each'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/reporter.rb:73:in `notify'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/reporter.rb:23:in `finish'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/reporter.rb:14:in `report'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/command_line.rb:21:in `run'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/runner.rb:80:in `run_in_process'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/runner.rb:69:in `run'
from /Users/Work/.rvm/gems/ruby-1.9.2-p290/gems/rspec-core-2.7.1/lib/rspec/core/runner.rb:10:in `block in autorun'
这真的很奇怪 - div.length是一个fixnum。这似乎是一个非常基本的断言，我不明白我在这里做错了什么。有人有指点吗？
我正在使用RSpec 2.7.1，RSpec期望值为2.7.0。我有Ruby 1.9.2p290。
编辑：快速说明 - 我要求通过Capybara进行RSpec。