//go:build linux

package hostfloor

import (
	"context"
	"os"
	"path/filepath"
	"strings"
	"testing"
)

// A guarded run returns the image's stdout only. A candidate that writes
// progress or an alert to stderr must not corrupt the version or JSON the
// updater parses from stdout (an armed box refused every router update that
// way); stderr still explains a failure.
func TestRunImageReturnsStdoutOnly(t *testing.T) {
	dir := t.TempDir()
	script := filepath.Join(dir, "img")
	if err := os.WriteFile(script, []byte("#!/bin/sh\necho noise >&2\necho '{\"ok\":true}'\n[ \"$1\" = fail ] && { echo why >&2; exit 3; }\nexit 0\n"), 0o755); err != nil {
		t.Fatal(err)
	}
	f, err := os.Open(script)
	if err != nil {
		t.Fatal(err)
	}
	defer f.Close()
	out, err := runImage(context.Background(), f, "ok")
	if err != nil || out != "{\"ok\":true}\n" {
		t.Fatalf("out %q err %v", out, err)
	}
	if _, err = f.Seek(0, 0); err != nil {
		t.Fatal(err)
	}
	_, err = runImage(context.Background(), f, "fail")
	if err == nil || !strings.Contains(err.Error(), "why") {
		t.Fatalf("failure lost its stderr: %v", err)
	}
}