Using rspec to test code prone to external infuence

I'm using rspec to test a code that may fail depending on the change of a site structure (the external influence I mentioned). I would like to write an example that involves "should raise an error" but开发者_开发知识库 I'm not sure if rspec is the right tool to test code in such situations. Could someone point me in some direction?

Thanks in advance

---

You could write custom matchers

Something like :

site.should_have_valid_structure

Spec::Matchers.define :have_structure
  match do |actual|
    actual.structure == Site::VALID_STRUCTURE
  end
end

---

Mock the external influence so you can test it properly (if the external influence is a Web page or other HTTP request, WebMock and VCR are great for this). Your tests should not rely on anything external functioning properly -- or improperly. See http://marnen.github.com/webmock-presentation/webmock.html for an overview I wrote last year.