env GO111MODULE=on

# explicit get should report errors about bad names
! go get appengine
stderr '^go get appengine: package appengine is not in GOROOT \(.*\)$'
! go get x/y.z
stderr 'malformed module path "x/y.z": missing dot in first path element'

# 'go list -m' should report errors about module names, never GOROOT.
! go list -m -versions appengine
stderr 'malformed module path "appengine": missing dot in first path element'
! go list -m -versions x/y.z
stderr 'malformed module path "x/y.z": missing dot in first path element'

# build should report all unsatisfied imports,
# but should be more definitive about non-module import paths
! go build ./useappengine
stderr 'cannot find package'
! go build ./usenonexistent
stderr 'cannot find module providing package nonexistent.rsc.io'

# go mod vendor and go mod tidy should ignore appengine imports.
rm usenonexistent/x.go
go mod tidy
go mod vendor

-- go.mod --
module x

-- useappengine/x.go --
package useappengine
import _ "appengine" // package does not exist
-- usenonexistent/x.go --
package usenonexistent
import _ "nonexistent.rsc.io" // domain does not exist