command: placeholder for <none> in kv output

command/helpers.go

@@ -8,6 +8,7 @@ import (
 // aligned k = v pairs using the columnize library.
 func formatKV(in []string) string {
 	columnConf := columnize.DefaultConfig()
+	columnConf.Empty = "<none>"
 	columnConf.Glue = " = "
 	return columnize.Format(in, columnConf)
 }

command/helpers_test.go

@@ -5,11 +5,12 @@ import (
 )
 
 func TestHelpers_FormatKV(t *testing.T) {
-	in := []string{"alpha|beta", "charlie|delta"}
+	in := []string{"alpha|beta", "charlie|delta", "echo|"}
 	out := formatKV(in)
 
 	expect := "alpha   = beta\n"
-	expect += "charlie = delta"
+	expect += "charlie = delta\n"
+	expect += "echo    = <none>"
 
 	if out != expect {
 		t.Fatalf("expect: %s, got: %s", expect, out)