Testdata can be used by other packages, e.g. github.com/go-git/go-git uses testdata of golang.org/x/crypto/ssh, but they are not provided by golang-x-crypto-devel, so building go-git (generated by go2rpm) fails because of failed dependency.
Also testdata are generally useful while developing and resulting binaries will not contain them anyway.
Testdata can be used by other packages, e.g. github.com/go-git/go-git uses testdata of golang.org/x/crypto/ssh, but they are not provided by golang-x-crypto-devel, so building go-git (generated by go2rpm) fails because of failed dependency.
Also testdata are generally useful while developing and resulting binaries will not contain them anyway.