[skybrian]

Perhaps a more intuitive name would be "round-trip serialization HTML". That is, if you use the browser to parse and print some HTML, it matches the source code.

Or in other words, it's formatted the same way that the browser would do it. So, you use the browser to pretty-print the HTML page, and save the code as the source. It's not hard at all and could be done automatically.

Round-trip tests are often used to check that a deserialization routine outputs data that can be serialized again and no data is lost. It even lets you change the serialization format, provided that you change the parser and printer to match.

I expect that these sort of tests are a lot more useful with fuzzing, though. Finding one example that works mostly just tells you that the browser's HTML printing code isn't completely broken. A single test of that sort is only useful for catching stupid bugs quickly.