[short] skip env GO111MODULE=off # test folder should work go test github.com/clsung/go-vendor-issue-14613 # test with specified _test.go should work too cd $GOPATH/src go test github.com/clsung/go-vendor-issue-14613/vendor_test.go # test with imported and not used ! go test github.com/clsung/go-vendor-issue-14613/vendor/mylibtesttest/myapp/myapp_test.go stderr 'imported and not used' -- $GOPATH/src/github.com/clsung/go-vendor-issue-14613/./vendor_test.go -- package main import ( "testing" "github.com/clsung/fake" ) func TestVendor(t *testing.T) { ret := fake.DoNothing() expected := "Ok" if expected != ret { t.Errorf("fake returned %q, expected %q", ret, expected) } } -- $GOPATH/src/github.com/clsung/go-vendor-issue-14613/./vendor/mylibtesttest/myapp/myapp_test.go -- package myapp import ( "mylibtesttest/rds" ) -- $GOPATH/src/github.com/clsung/go-vendor-issue-14613/./vendor/mylibtesttest/rds/rds.go -- package rds -- $GOPATH/src/github.com/clsung/go-vendor-issue-14613/./vendor/github.com/clsung/fake/fake.go -- package fake func DoNothing() string { return "Ok" } -- $GOPATH/src/github.com/clsung/go-vendor-issue-14613/./m.go -- package main func main() {}