godog: failed to compile testmain package:

I am getting a compilation error when running godog on example folder.

Go version:

$ go version
go version go1.7.4 darwin/amd64

I installed godog:

$ go get -u github.com/DATA-DOG/godog

Then I go into the godogs example directory:

$ cd $GOPATH
$ cd src/go/src/github.com/DATA-DOG/godog/examples/godogs

And run godog:

$ godog
failed to compile testmain package: