How to assert duplicate record while updating or inserting record Test case for API in ruby on rails using fakeweb

options = {:body => fixture_file("parse.xml"),:content_type => "application/xml",:status =>["200", "OK"]}
FakeWeb.register_uri(:get, @url, options)
doc = Nokogiri::XML(open(@url,:ssl_verify_mode => OpenSSL::SSL开发者_开发技巧::VERIFY_NONE))

should "cases should not insert duplicate record" do

      doc.xpath('//cases/case').each do |case|

      end
end 

here inserting or updating record using Model.find_or_initialize_by_id(case['ixBug']), how i should check this condition in test case by putting assertion?

I think you should check for duplicate records using model validations. It seems you're doing integration testing (that is useful to test controller responses and/or test that all the environment is working well).

it doesn't make sense to test data duplication there.