This directory holds Go modules served by a Go module proxy
that runs on localhost during tests, both to make tests avoid
requiring specific network servers and also to make them 
significantly faster.

A small go get'able test module can be added here by running

	cd cmd/go/testdata
	go run addmod.go path@vers

where path and vers are the module path and version to add here.

For interactive experimentation using this set of modules, run:

	cd cmd/go
	go test -proxy=localhost:1234 &
	export GOPROXY=http://localhost:1234/mod

and then run go commands as usual.

Modules saved to this directory should be small: a few kilobytes at most.
It is acceptable to edit the archives created by addmod.go to remove
or shorten files. It is also acceptable to write module archives by hand: 
they need not be backed by some public git repo.

Each module archive is named path_vers.txt, where slashes in path
have been replaced with underscores. The archive must contain
two files ".info" and ".mod", to be served as the info and mod files
in the proxy protocol (see https://research.swtch.com/vgo-module).
The remaining files are served as the content of the module zip file.
The path@vers prefix required of files in the zip file is added
automatically by the proxy: the files in the archive have names without
the prefix, like plain "go.mod", "x.go", and so on.

See ../addmod.go and ../savedir.go for tools to generate txtar files,
although again it is also fine to write them by hand.