Add function and test for processing sub command args

main.go

@@ -8,7 +8,6 @@ import (
 	"net"
 	"net/url"
 	"os"
-	"strings"
 
 	"github.com/nats-io/gnatsd/auth"
 	"github.com/nats-io/gnatsd/logger"
@@ -138,16 +137,13 @@ func main() {
 
 	// Process args looking for non-flag options,
 	// 'version' and 'help' only for now
-	if len(flag.Args()) > 0 {
-		switch strings.ToLower(flag.Args()[0]) {
-		case "version":
-			server.PrintServerAndExit()
-		case "help":
-			usage()
-		default:
-			// Unrecognized command
-			usage()
-		}
+	showVersion, showHelp, err := server.ProcessCommandLineArgs(flag.CommandLine)
+	if err != nil {
+		server.PrintAndDie(err.Error() + usageStr)
+	} else if showVersion {
+		server.PrintServerAndExit()
+	} else if showHelp {
+		usage()
 	}
 
 	// Parse config if given

server/server.go

@@ -6,6 +6,7 @@ import (
 	"bufio"
 	"crypto/tls"
 	"encoding/json"
+	"flag"
 	"fmt"
 	"io/ioutil"
 	"net"
@@ -13,6 +14,7 @@ import (
 	"os"
 	"runtime"
 	"strconv"
+	"strings"
 	"sync"
 	"time"
 
@@ -180,6 +182,25 @@ func PrintServerAndExit() {
 	os.Exit(0)
 }
 
+// ProcessCommandLineArgs takes the command line arguments
+// validating and setting flags for handling in case any
+// sub command was present.
+func ProcessCommandLineArgs(cmd *flag.FlagSet) (showVersion bool, showHelp bool, err error) {
+	if len(cmd.Args()) > 0 {
+		arg := cmd.Args()[0]
+		switch strings.ToLower(arg) {
+		case "version":
+			return true, false, nil
+		case "help":
+			return false, true, nil
+		default:
+			return false, false, fmt.Errorf("Unrecognized command: %q\n", arg)
+		}
+	}
+
+	return false, false, nil
+}
+
 // Protected check on running state
 func (s *Server) isRunning() bool {
 	s.mu.Lock()

server/server_test.go

@@ -8,6 +8,7 @@ import (
 	"strings"
 	"testing"
 	"time"
+	"flag"
 
 	"github.com/nats-io/go-nats"
 )
@@ -246,3 +247,50 @@ func TestMaxConnections(t *testing.T) {
 		t.Fatal("Expected connection to fail")
 	}
 }
+
+func TestProcessCommandLineArgs(t *testing.T) {
+	var host string
+	var port int
+	cmd := flag.NewFlagSet("gnatsd", flag.ExitOnError)
+	cmd.StringVar(&host, "a", "0.0.0.0", "Host.")
+	cmd.IntVar(&port, "p", 4222, "Port.")
+
+	cmd.Parse([]string{"-a", "127.0.0.1", "-p", "9090"})
+	showVersion, showHelp, err := ProcessCommandLineArgs(cmd)
+	if err != nil {
+		t.Errorf("Expected no errors, got: %s", err)
+	}
+	if showVersion || showHelp {
+		t.Errorf("Expected not having to handle subcommands")
+	}
+
+	cmd.Parse([]string{"version"})
+	showVersion, showHelp, err = ProcessCommandLineArgs(cmd)
+	if err != nil {
+		t.Errorf("Expected no errors, got: %s", err)
+	}
+	if !showVersion {
+		t.Errorf("Expected having to handle version command")
+	}
+	if showHelp {
+		t.Errorf("Expected not having to handle help command")
+	}
+
+	cmd.Parse([]string{"help"})
+	showVersion, showHelp, err = ProcessCommandLineArgs(cmd)
+	if err != nil {
+		t.Errorf("Expected no errors, got: %s", err)
+	}
+	if showVersion {
+		t.Errorf("Expected not having to handle version command")
+	}
+	if !showHelp {
+		t.Errorf("Expected having to handle help command")
+	}
+
+	cmd.Parse([]string{"foo", "-p", "9090"})
+	_, _, err = ProcessCommandLineArgs(cmd)
+	if err == nil {
+		t.Errorf("Expected an error handling the command arguments")
+	}
+}