# When finding the latest version of a module, we should not download version
# contents. Previously, we downloaded .zip files to determine whether a real
# .mod file was present in order to decide whether +incompatible versions
# could be "latest".
#
# Verifies #47377.

# rsc.io/breaker has two versions, neither of which has a .mod file.
go list -m -versions rsc.io/breaker
stdout '^rsc.io/breaker v1.0.0 v2.0.0\+incompatible$'
go mod download rsc.io/[email protected]
! grep '^go' $GOPATH/pkg/mod/cache/download/rsc.io/breaker/@v/v1.0.0.mod
go mod download rsc.io/[email protected]+incompatible
! grep '^go' $GOPATH/pkg/mod/cache/download/rsc.io/breaker/@v/v2.0.0+incompatible.mod

# Delete downloaded .zip files.
go clean -modcache

# Check for updates.
go list -m -u rsc.io/breaker
stdout '^rsc.io/breaker v1.0.0 \[v2.0.0\+incompatible\]$'

# We should not have downloaded zips.
! exists $GOPATH/pkg/mod/cache/download/rsc.io/breaker/@v/v1.0.0.zip
! exists $GOPATH/pkg/mod/cache/download/rsc.io/breaker/@v/v2.0.0+incompatible.zip

-- go.mod --
module m

go 1.16

require rsc.io/breaker v1.0.0
-- go.sum --
rsc.io/breaker v1.0.0/go.mod h1:s5yxDXvD88U1/ESC23I2FK3Lkv4YIKaB1ij/Hbm805g=