package authentication

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

func TestWriteFileAtomic(t *testing.T) {
	dir := t.TempDir()
	file := filepath.Join(dir, "authentication.json")

	if err := writeFileAtomic(file, []byte("{\"a\":1}"), 0600); err != nil {
		t.Fatal(err)
	}
	if err := writeFileAtomic(file, []byte("{\"a\":2}"), 0600); err != nil {
		t.Fatal(err)
	}

	got, err := os.ReadFile(file)
	if err != nil {
		t.Fatal(err)
	}
	if string(got) != "{\"a\":2}" {
		t.Errorf("content = %q", got)
	}

	fi, err := os.Stat(file)
	if err != nil {
		t.Fatal(err)
	}
	if fi.Mode().Perm() != 0600 {
		t.Errorf("mode = %o, want 0600", fi.Mode().Perm())
	}

	entries, err := os.ReadDir(dir)
	if err != nil {
		t.Fatal(err)
	}
	if len(entries) != 1 {
		t.Errorf("expected only the target file, found %d entries", len(entries))
	}
}