[tjpnz]

>Parsoid/JS had very few unit tests focused on specific subsections of code. With only integration tests we would find it difficult to test anything but a complete and finished port.

I found this a little frightening given Parsoid/JS is handling user input.

[cscottnet]

There are thousands of integration tests. The "correct" output of the parser is well-known for a given input, and those test cases have been accumulating for over a decade. But the internal structure of the parser is much more fluid, and so it wasn't (historically) thought worthwhile to try to write tests against that shifting target.