Is there a ruby gem that does diff between HTML do

Question

Doing a diff of two different html documents turns out to be an entirely different problem than simply doing a diff of plain text. For example, if I do a naive LCS diff between:

Google</p>

and

Google</a></p>

---

the diff result is NOT:

</a>

but

/a></

---

I've tried most gems out there that claim to be html diff but all of them seem to be just implementing text based LCS diff. Is there any gem that does a diff while taking html tags into account?

Answer 1

Try Samy diffy or rubygems html-diff

Answer 2

After much searching for a gem to do this for me, I discovered that I can simply do a string compare between two parsed Nokogiri documents:

def should_match_html(html_text1, html_text2)
  dom1 = Nokogiri::HTML(html_text1)
  dom2 = Nokogiri::HTML(html_text2)
  dom1.to_s.should == dom2.to_s
end

Then you can simply add this in your spec:

should_match_html expected_html, actual_html

The best part is that the built-in rspec matcher will automatically provide you a line-by-line diff result of the mismatched lines.