env GO111MODULE=on
env GOSUMDB=off

go mod download example.com/join@v1.1.0

# If the proxy serves a bogus result for the @latest version,
# reading that version should cause 'go get' to fail.
env GOPROXY=file:///$WORK/badproxy
cp go.mod.orig go.mod
! go get -d example.com/join/subpkg
stderr 'go get: example.com/join/subpkg@v0.0.0-20190624000000-123456abcdef: .*'

# If @v/list is empty, the 'go' command should still try to resolve
# other module paths.
env GOPROXY=file:///$WORK/emptysub
cp go.mod.orig go.mod
go get -d example.com/join/subpkg
go list -m example.com/join/...
! stdout 'example.com/join/subpkg'
stdout 'example.com/join v1.1.0'

# If @v/list includes a version that the proxy does not actually serve,
# that version is treated as nonexistent.
env GOPROXY=file:///$WORK/notfound
cp go.mod.orig go.mod
go get -d example.com/join/subpkg
go list -m example.com/join/...
! stdout 'example.com/join/subpkg'
stdout 'example.com/join v1.1.0'

# If the proxy provides an empty @v/list but rejects @latest with
# some other explicit error (for example, a "permission denied" error),
# that error should be reported to the user (and override a successful
# result for other possible module paths).
#
# Depending on how the specific platform enforces permissions, the 'go get' may
# fail either due to the intended permission error or due to a parse error.
# We accept either failure message.
env GOPROXY=file:///$WORK/gatekeeper
chmod 0000 $WORK/gatekeeper/example.com/join/subpkg/@latest
cp go.mod.orig go.mod
! go get -d example.com/join/subpkg
stderr 'go get: module example.com/join/subpkg: (invalid response from proxy ".+": invalid character .+|reading file://.*/gatekeeper/example.com/join/subpkg/@latest: .+)'

-- go.mod.orig --
module example.com/othermodule
go 1.13
-- $WORK/badproxy/example.com/join/subpkg/@v/list --
v0.0.0-20190624000000-123456abcdef
-- $WORK/badproxy/example.com/join/subpkg/@v/v0.0.0-20190624000000-123456abcdef.info --
This file is not valid JSON.
-- $WORK/badproxy/example.com/join/@v/list --
v1.1.0
-- $WORK/badproxy/example.com/join/@v/v1.1.0.info --
{"Version": "v1.1.0"}
-- $WORK/emptysub/example.com/join/subpkg/@v/list --
-- $WORK/emptysub/example.com/join/@v/list --
v1.1.0
-- $WORK/emptysub/example.com/join/@v/v1.1.0.info --
{"Version": "v1.1.0"}
-- $WORK/notfound/example.com/join/subpkg/@v/list --
v1.0.0-does-not-exist
-- $WORK/notfound/example.com/join/@v/list --
v1.1.0
-- $WORK/notfound/example.com/join/@v/v1.1.0.info --
{"Version": "v1.1.0"}
-- $WORK/gatekeeper/example.com/join/subpkg/@v/list --
-- $WORK/gatekeeper/example.com/join/subpkg/@latest --
ERROR: Latest version is forbidden.
-- $WORK/gatekeeper/example.com/join/@v/list --
v1.1.0
-- $WORK/gatekeeper/example.com/join/@v/v1.1.0.info --
{"Version": "v1.1.0"}