Golang Dep不会下载所有库文件

I use docker library in my $GOPATH/src/github.com/docker Now I try use dep. in my gopkg.toml, it has following description

[[constraint]]
  name = "github.com/docker/docker"
  version = "1.13.1"

But after dep init completed, all my codes tell me

Unresolved reference 'NewClientWithOpts'

But it works before I use dep.

client.NewClientWithOpts(client.WithVersion("1.38"))

When I look up my library from vendor. there are 105 files.

But from my src/github.com/docker/client, It has 212 items!!

My question: Why dep not download all library files? How I solve this problem?

You have version 1.13.1 as your constraint in the Gopkg.toml file, but NewClientWithOpts() was introduced after that version. You could either try setting the constraint as branch = "master" or revision = "<latest_commit_sha>", or use the v1.13.1 release and look at docs for that specific version.

dep doesn't necessarily include all the files from a package - it only keeps sub-packages that are actually being used. That's not a problem in this case though.