The original approach of running version, but that seems to bypass wrappedMain entirely

command/exec_test.go

@@ -95,6 +95,8 @@ func TestHelperProcess(*testing.T) {
 		os.Exit((&BuildCommand{Meta: commandMeta()}).Run(args))
 	case "hcl2_upgrade":
 		os.Exit((&HCL2UpgradeCommand{Meta: commandMeta()}).Run(args))
+	case "version":
+		os.Exit((&VersionCommand{Meta: commandMeta()}).Run(args))
 	default:
 		fmt.Fprintf(os.Stderr, "Unknown command %q\n", cmd)
 		os.Exit(2)

command/version_test.go

 package command
 
 import (
+	"fmt"
 	"testing"
 
+	"github.com/hashicorp/packer/version"
 	"github.com/mitchellh/cli"
+	"github.com/stretchr/testify/assert"
 )
 
 func TestVersionCommand_implements(t *testing.T) {
 	var _ cli.Command = &VersionCommand{}
 }
+
+func Test_version(t *testing.T) {
+	tc := []struct {
+		command  []string
+		env      []string
+		expected string
+	}{
+		{[]string{"version"}, nil, fmt.Sprintf("Packer v%s", version.FormattedVersion()) + "\n"},
+		{[]string{"version", "&"}, nil, fmt.Sprintf("Packer v%s", version.FormattedVersion()) + "\n"},
+	}
+
+	for _, tc := range tc {
+		t.Run(fmt.Sprintf("packer %s", tc.command), func(t *testing.T) {
+			p := helperCommand(t, tc.command...)
+			bs, err := p.Output()
+			fmt.Println(err)
+			if err != nil {
+				t.Fatalf("%v: %s", err, bs)
+			}
+			assert.Equal(t, tc.expected, string(bs))
+		})
+	}
+}