Add tests for watch_for_kitty_config_changes Go function

Fixes #9882

tools/watch/api.go

@@ -81,24 +81,44 @@ func get_unique_directories(paths []string) []string {
 	return result
 }
 
+// resolve_path resolves symlinks in the directory component of path so the result
+// matches what the OS-level file-system watcher (FSEvents on macOS, inotify on Linux)
+// reports. This is important on macOS where /tmp is a symlink to /private/tmp.
+// If the directory cannot be resolved (e.g. it doesn't exist yet) the path is
+// returned cleaned but unresolved.
+func resolve_path(path string) string {
+	dir := filepath.Dir(path)
+	if resolved, err := filepath.EvalSymlinks(dir); err == nil {
+		return filepath.Join(resolved, filepath.Base(path))
+	}
+	return filepath.Clean(path)
+}
+
 func get_set_of_config_files(config_paths []string) *utils.Set[string] {
 	cp := config.ConfigParser{
 		AllIncludedFiles: utils.NewSet[string](), LineHandler: func(k, v string) error { return nil }}
 	cp.ParseFiles(config_paths...)
+	// Resolve symlinks in all paths collected by the parser (important on macOS
+	// where /tmp -> /private/tmp causes mismatches with FSEvents-reported paths).
+	result := utils.NewSet[string](cp.AllIncludedFiles.Len() + len(config_paths)*4)
+	for _, p := range cp.AllIncludedFiles.AsSlice() {
+		result.Add(resolve_path(p))
+	}
 	for _, path := range config_paths {
-		path = filepath.Clean(path)
-		cp.AllIncludedFiles.Add(path)
+		path = resolve_path(path)
+		result.Add(path)
+		dir := filepath.Dir(path)
 		for _, q := range []string{"dark-theme.auto.conf", "light-theme.auto.conf", "no-preference-theme.auto.conf"} {
-			q = filepath.Join(filepath.Dir(path), q)
-			cp.AllIncludedFiles.Add(filepath.Clean(q))
+			result.Add(resolve_path(filepath.Join(dir, q)))
 		}
 	}
-	return cp.AllIncludedFiles
+	return result
 }
 
-func watch_for_kitty_config_changes(action func() error, debounce_time time.Duration, config_paths []string) error {
-	ctx, cancel := context.WithCancel(context.Background())
-	defer cancel()
+// watch_for_config_changes watches the directories derived from config_paths and calls action
+// whenever a watched config file (including includes and auto color scheme files) changes.
+// It runs until ctx is cancelled.
+func watch_for_config_changes(ctx context.Context, action func() error, debounce_time time.Duration, config_paths []string) error {
 	event_chan := make(chan fswatcher.WatchEvent)
 	all_paths := get_set_of_config_files(config_paths)
 	dirs_to_watch := get_unique_directories(all_paths.AsSlice())
@@ -108,7 +128,7 @@ func watch_for_kitty_config_changes(action func() error, debounce_time time.Dura
 
 	filtered_action := func(ev fswatcher.WatchEvent) error {
 		all_paths := get_set_of_config_files(config_paths)
-		if all_paths.Has(filepath.Clean(ev.Path)) {
+		if all_paths.Has(resolve_path(ev.Path)) {
 			return action()
 		}
 		return nil
@@ -117,25 +137,30 @@ func watch_for_kitty_config_changes(action func() error, debounce_time time.Dura
 	if err := watch_dirs(ctx, dirs_to_watch, debounce_time, event_chan); err != nil {
 		return err
 	}
-	stdinClosed := make(chan struct{})
-	go func() {
-		scanner := bufio.NewScanner(os.Stdin)
-		for scanner.Scan() {
-		}
-		close(stdinClosed)
-	}()
 	for {
 		select {
 		case event := <-event_chan:
 			if err := filtered_action(event); err != nil {
 				fmt.Fprintf(os.Stderr, "failed to signal kitty in event: %s with error: %s\n", event, err)
 			}
-		case <-stdinClosed:
+		case <-ctx.Done():
 			return nil
 		}
 	}
 }
 
+func watch_for_kitty_config_changes(action func() error, debounce_time time.Duration, config_paths []string) error {
+	ctx, cancel := context.WithCancel(context.Background())
+	defer cancel()
+	go func() {
+		scanner := bufio.NewScanner(os.Stdin)
+		for scanner.Scan() {
+		}
+		cancel()
+	}()
+	return watch_for_config_changes(ctx, action, debounce_time, config_paths)
+}
+
 func signal_kitty_to_reload_config(kitty_pid int) error {
 	return unix.Kill(kitty_pid, unix.SIGUSR1)
 }