env GO111MODULE=on

go mod download rsc.io/quote@v1.5.0
exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.0.info
exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.0.mod
exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.0.zip

go clean -modcache -n
stdout '^rm -rf .*pkg.mod$'
exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.0.info
exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.0.mod
exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.0.zip

go clean -modcache
! exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.0.info
! exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.0.mod
! exists $GOPATH/pkg/mod/cache/download/rsc.io/quote/@v/v1.5.0.zip

-- go.mod --
module m

-- m.go --
package m