package state

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

// The test is on write itself: a state file is read before it is
// written, and a directory in its place fails that read first.
func TestFailedRenameLeavesNoTemporaryFile(t *testing.T) {
	t.Parallel()

	dir := t.TempDir()

	// A directory named bans.json cannot be renamed over.
	err := os.Mkdir(filepath.Join(dir, bansJSON), 0o700)
	if err != nil {
		t.Fatalf("mkdir: %v", err)
	}

	err = write(dir, bansJSON, []byte("{}\n"))
	if err == nil {
		t.Error("writing over a directory did not fail")
	}

	entries, err := os.ReadDir(dir)
	if err != nil {
		t.Fatalf("read %s: %v", dir, err)
	}

	if len(entries) != 1 || entries[0].Name() != bansJSON {
		t.Errorf("%s holds %v, want only bans.json", dir, entries)
	}
}