It happens that I was in need of a TAP v13 parser for Go the other day, and I didn't find one that met our needs. So I wrote one; maybe it's useful to someone else, too:

https://github.com/mpontillo/tap13

TL;DR: it takes TAP output (in the form of a []string, one string per line) and produces a Results struct containing an array of Test structs. The goal was to sufficiently parse the TAP output so that it could be transformed sufficiently for storage in other systems.