From the 1.17 release notes (https://golang.org/doc/go1.17#gofmt): gofmt (and go fmt) now synchronizes //go:build lines with // +build lines. More info about this change can be found at https://golang.org/design/draft-gobuild
By default, the prove(1) program looks for tests to run in the 't' directory at the repository root, so let's put existing tests there in order to remove a non-default argument from prove.