While working on the RFC 8555 implementation for golang/go#21081, I've been also manually verifying the functionality against various CAs both draft-02 and RFC versions. This does not of course replace automated tests yet it might be useful to others. It is not a _test.go file because the program may require interactive user input for dns-01 challenge types and needs to flush logs to stderr during its run. Change-Id: Ia324b08b30308441cc0705648e30c0112b0fa0c8 Reviewed-on: https://go-review.googlesource.com/c/crypto/+/194681 Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>