env GO111MODULE=on
env proxy=$GOPROXY

# Proxy that can't serve should fail.
env GOPROXY=$proxy/404
! go get rsc.io/[email protected]
stderr '404 Not Found'

# get should walk down the proxy list past 404 and 410 responses.
env GOPROXY=$proxy/404,$proxy/410,$proxy
go get rsc.io/[email protected]

# get should not walk past other 4xx errors if proxies are separated with ','.
env GOPROXY=$proxy/403,$proxy
! go get rsc.io/[email protected]
stderr 'reading.*/403/rsc.io/.*: 403 Forbidden'

# get should not walk past non-4xx errors if proxies are separated with ','.
env GOPROXY=$proxy/500,$proxy
! go get rsc.io/[email protected]
stderr 'reading.*/500/rsc.io/.*: 500 Internal Server Error'

# get should walk past other 4xx errors if proxies are separated with '|'.
env GOPROXY=$proxy/403|https://0.0.0.0|$proxy
go get rsc.io/[email protected]

# get should walk past non-4xx errors if proxies are separated with '|'.
env GOPROXY=$proxy/500|https://0.0.0.0|$proxy
go get rsc.io/[email protected]

# get should return the final error if that's all we have.
env GOPROXY=$proxy/404,$proxy/410
! go get rsc.io/[email protected]
stderr 'reading.*/410/rsc.io/.*: 410 Gone'

-- go.mod --
module x