Where is the default cache location of Go test files?

From the Go testing documentation:

When 'go test' runs in package list mode, 'go test' caches successful package test results to avoid unnecessary repeated running of tests.

This all works fine for me. However, I cannot find an official list of cache directories per platform in the documentation. I can take a guess that it might be stored in $HOME/.cache/go-build on Linux?

So far I have read the source code, searched the documentation (as linked above), and read the output of go help test and go help cache but still can't see a definitive answer.