fix(cli): return failure for invalid commands

cmd/root.go

@@ -1,6 +1,8 @@
 package cmd
 
 import (
+	"os"
+
 	"github.com/amp-labs/cli/flags"
 	"github.com/amp-labs/cli/logger"
 	"github.com/spf13/cobra"
@@ -21,7 +23,7 @@ var rootCmd = &cobra.Command{ //nolint:gochecknoglobals
 func Execute() {
 	err := rootCmd.Execute()
 	if err != nil {
-		return
+		os.Exit(1)
 	}
 }
 

cmd/root_test.go

@@ -0,0 +1,49 @@
+package cmd
+
+import (
+	"errors"
+	"os"
+	"os/exec"
+	"strings"
+	"testing"
+)
+
+const executeUnknownCommandEnv = "AMP_TEST_EXECUTE_UNKNOWN_COMMAND"
+
+func TestExecuteExitsWithFailureForUnknownCommand(t *testing.T) {
+	t.Parallel()
+
+	if os.Getenv(executeUnknownCommandEnv) == "1" {
+		os.Args = []string{"amp", "definitely-not-a-command"}
+
+		Execute()
+
+		return
+	}
+
+	// This test intentionally executes the current test binary.
+	//nolint:gosec
+	command := exec.CommandContext(
+		t.Context(), os.Args[0], "-test.run=^TestExecuteExitsWithFailureForUnknownCommand$",
+	)
+
+	command.Env = append(os.Environ(), executeUnknownCommandEnv+"=1")
+
+	output, err := command.CombinedOutput()
+	if err == nil {
+		t.Fatalf("Execute() exited successfully for an unknown command: %s", output)
+	}
+
+	var exitError *exec.ExitError
+	if !errors.As(err, &exitError) {
+		t.Fatalf("Execute() returned %T, want an exit error", err)
+	}
+
+	if exitError.ExitCode() != 1 {
+		t.Fatalf("Execute() returned exit code %d, want 1", exitError.ExitCode())
+	}
+
+	if !strings.Contains(string(output), `unknown command "definitely-not-a-command"`) {
+		t.Fatalf("Execute() output = %q, want unknown command error", output)
+	}
+}