Fix panic handling and add a new exit code and a test for panics

cmd/root.go

@@ -6,6 +6,7 @@ import (
 	"fmt"
 	"io"
 	stdlog "log"
+	"runtime/debug"
 	"strconv"
 	"strings"
 	"sync"
@@ -17,6 +18,7 @@ import (
 
 	"go.k6.io/k6/cmd/state"
 	"go.k6.io/k6/errext"
+	"go.k6.io/k6/errext/exitcodes"
 	"go.k6.io/k6/lib/consts"
 	"go.k6.io/k6/log"
 )
@@ -88,6 +90,17 @@ func (c *rootCommand) execute() {
 		c.globalState.OSExit(exitCode)
 	}()
 
+	defer func() {
+		if r := recover(); r != nil {
+			exitCode = int(exitcodes.GoPanic)
+			err := fmt.Errorf("unexpected k6 panic: %s\n%s", r, debug.Stack())
+			if c.loggerIsRemote {
+				c.globalState.FallbackLogger.Error(err)
+			}
+			c.globalState.Logger.Error(err)
+		}
+	}()
+
 	err := c.cmd.Execute()
 	if err == nil {
 		exitCode = 0

cmd/root_test.go

@@ -5,8 +5,10 @@ import (
 	"testing"
 
 	"github.com/sirupsen/logrus"
+	"github.com/spf13/cobra"
 	"github.com/stretchr/testify/assert"
 	"go.k6.io/k6/cmd/tests"
+	"go.k6.io/k6/errext/exitcodes"
 	"go.k6.io/k6/lib/testutils"
 )
 
@@ -37,3 +39,25 @@ func TestDeprecatedOptionWarning(t *testing.T) {
 	assert.False(t, testutils.LogContains(logMsgs, logrus.InfoLevel, "logformat"))
 	assert.Contains(t, ts.Stdout.String(), `--logformat has been deprecated`)
 }
+
+func TestPanicHandling(t *testing.T) {
+	t.Parallel()
+
+	ts := tests.NewGlobalTestState(t)
+	ts.CmdArgs = []string{"k6", "panic"}
+	ts.ExpectedExitCode = int(exitcodes.GoPanic)
+
+	rootCmd := newRootCommand(ts.GlobalState)
+	rootCmd.cmd.AddCommand(&cobra.Command{
+		Use: "panic",
+		RunE: func(cmd *cobra.Command, args []string) error {
+			panic("oh no, oh no, oh no,no,no,no,no")
+		},
+	})
+	rootCmd.execute()
+
+	t.Log(ts.Stderr.String())
+	logMsgs := ts.LoggerHook.Drain()
+	assert.True(t, testutils.LogContains(logMsgs, logrus.ErrorLevel, "unexpected k6 panic: oh no"))
+	assert.True(t, testutils.LogContains(logMsgs, logrus.ErrorLevel, "cmd.TestPanicHandling")) // check stacktrace
+}

errext/exitcodes/codes.go

@@ -20,4 +20,5 @@ const (
 	CannotStartRESTAPI       ExitCode = 106
 	ScriptException          ExitCode = 107
 	ScriptAborted            ExitCode = 108
+	GoPanic                  ExitCode = 109
 )