Fix 'double print bug' for unrecognized flags

We moved to using our own flagset in the previous commit, which lets us
then instantiate it with 'ContinueOnError', and catch the parsing error
ourselves and print it once, rather than being stuck with the pflag bug
that results in the error being double printed
(spf13/pflag#352).

core/runner.go

@@ -21,7 +21,7 @@ func NewRadRunner(runnerInput RunnerInput) *RadRunner {
 
 func (r *RadRunner) Run() error {
 	// don't fail on unknown flags. they may be intended for the script, which we won't have parsed initially
-	RFlagSet = pflag.NewFlagSet(os.Args[0], pflag.ExitOnError)
+	RFlagSet = pflag.NewFlagSet(os.Args[0], pflag.ContinueOnError)
 	RFlagSet.ParseErrorsWhitelist.UnknownFlags = true
 
 	RFlagSet.Usage = func() {
@@ -105,13 +105,13 @@ func (r *RadRunner) Run() error {
 	// help not explicitly invoked, so let's try parsing other args
 
 	// re-enable erroring on unknown flags. note: maybe remove for 'catchall' args?
-	// todo if unknown flag passed, pflag handles the error & prints a kinda ugly msg (twice, bug).
-	//  continue allowing unknown flags and then detect ourselves?
 	RFlagSet.ParseErrorsWhitelist.UnknownFlags = false
 
-	// todo apparently this is not recommended, I should be using flagsets? i.e. create new one? I THINK I DO, FOR TESTS?
-	//  RAD-67 will prevent double-error print (see https://github.com/spf13/pflag/issues/352)
-	RFlagSet.Parse(os.Args[1:])
+	// technically re-using the flagset is apparently discouraged, but i've yet to see where it goes wrong
+	err = RFlagSet.Parse(os.Args[1:])
+	if err != nil {
+		RP.UsageErrorExit(err.Error())
+	}
 
 	posArgsIndex := 0
 	if FlagStdinScriptName.Value == "" {
@@ -196,6 +196,7 @@ func (r *RadRunner) createRslArgsFromScript() []RslArg {
 
 	return flags
 }
+
 func readSource(scriptPath string) string {
 	source, err := os.ReadFile(scriptPath)
 	if err != nil {

core/testing/args_test.go

@@ -1,7 +1,6 @@
 package testing
 
 import (
-	"fmt"
 	"testing"
 )
 
@@ -414,22 +413,20 @@ Script args:
 	resetTestState()
 }
 
-// todo RAD-67 - pflag currently ExitsOnError, I think that's why this test doesn't work
 func TestArgs_InvalidFlagPrintsUsageAndReturnsError(t *testing.T) {
-	t.Skip("TODO: RAD-67")
 	rsl := `
 args:
 	name string
 	age int
 `
-	fmt.Println("hi")
 	setupAndRunCode(t, rsl, "alice", "2", "-s", "--NO-COLOR")
-	expected := `Usage:
- test <name> <age>
+	expected := `unknown shorthand flag: 's' in -s
+Usage:
+  test <name> <age>
 
 Script args:
-     --name string
-     --age int
+      --name string   
+      --age int       
 
 ` + globalFlagHelp
 	assertError(t, 1, expected)