e2e: detect unexpected command line arguments

Invalid flags are detected by flag parsing, but optional arguments are just
passed through to the E2E suites. None of them support any, so rejecting them
with an error message is useful because it helps catch typos (like a missing
hyphen before a flag).

test/e2e/e2e_test.go

@@ -92,6 +92,11 @@ func TestMain(m *testing.M) {
 		os.Exit(0)
 	}
 
+	if flag.CommandLine.NArg() > 0 {
+		fmt.Fprintf(os.Stderr, "unknown additional command line arguments: %s", flag.CommandLine.Args())
+		os.Exit(1)
+	}
+
 	// Enable embedded FS file lookup as fallback
 	testfiles.AddFileSource(e2etestingmanifests.GetE2ETestingManifestsFS())
 	testfiles.AddFileSource(testfixtures.GetTestFixturesFS())

test/e2e_kubeadm/e2e_kubeadm_suite_test.go

@@ -18,6 +18,7 @@ package kubeadm
 
 import (
 	"flag"
+	"fmt"
 	"os"
 	"testing"
 
@@ -42,6 +43,10 @@ func TestMain(m *testing.M) {
 	framework.RegisterClusterFlags(flag.CommandLine)
 	pflag.CommandLine.AddGoFlagSet(flag.CommandLine)
 	pflag.Parse()
+	if pflag.CommandLine.NArg() > 0 {
+		fmt.Fprintf(os.Stderr, "unknown additional command line arguments: %s", pflag.CommandLine.Args())
+		os.Exit(1)
+	}
 	framework.AfterReadingAllFlags(&framework.TestContext)
 	os.Exit(m.Run())
 }

test/e2e_node/e2e_node_suite_test.go

@@ -130,6 +130,10 @@ func TestMain(m *testing.M) {
 
 	rand.Seed(time.Now().UnixNano())
 	pflag.Parse()
+	if pflag.CommandLine.NArg() > 0 {
+		fmt.Fprintf(os.Stderr, "unknown additional command line arguments: %s", pflag.CommandLine.Args())
+		os.Exit(1)
+	}
 	framework.AfterReadingAllFlags(&framework.TestContext)
 	if err := e2eskipper.InitFeatureGates(utilfeature.DefaultFeatureGate, featureGates); err != nil {
 		fmt.Fprintf(os.Stderr, "ERROR: initialize feature gates: %v", err)