I find traditional unit testing limiting because you have to design the tests (and may miss a corner case etc). Having other people use the code generally presents you with situations you may not have thought of or may not have planned to address until later.
Especially with a mammoth project, incremental development is easier when you know what aspects are most important. I have been doing this with http://niggler.github.io/js-xlsx/ and it proved to be effective when others started using it in ways I didn't plan to address until later.
I find traditional unit testing limiting because you have to design the tests (and may miss a corner case etc). Having other people use the code generally presents you with situations you may not have thought of or may not have planned to address until later.
Especially with a mammoth project, incremental development is easier when you know what aspects are most important. I have been doing this with http://niggler.github.io/js-xlsx/ and it proved to be effective when others started using it in ways I didn't plan to address until later.