try some more tsting

internal/fswatcher/inotify/inotify.go

@@ -0,0 +1,67 @@
+package inotify
+
+import (
+	"fmt"
+)
+
+type InotifySyscalls interface {
+	Init() (int, error)
+	AddWatch(int, string) (int, error)
+	Close(int) error
+}
+
+type Inotify struct {
+	FD       int
+	Watchers map[int]*Watcher
+	sys      InotifySyscalls
+}
+
+func NewInotify(isys InotifySyscalls) (*Inotify, error) {
+	fd, err := isys.Init()
+	if err != nil {
+		return nil, fmt.Errorf("initializing inotify: %v", err)
+	}
+
+	i := &Inotify{
+		FD:       fd,
+		Watchers: make(map[int]*Watcher),
+		sys:      isys,
+	}
+
+	return i, nil
+}
+
+func (i *Inotify) Watch(dir string) error {
+	wd, err := i.sys.AddWatch(i.FD, dir)
+	if err != nil {
+		return fmt.Errorf("adding watcher on %s: %v", dir, err)
+	}
+	i.Watchers[wd] = &Watcher{
+		WD:  wd,
+		Dir: dir,
+	}
+	return nil
+}
+
+func (i *Inotify) Close() error {
+	if err := i.sys.Close(i.FD); err != nil {
+		return fmt.Errorf("closing inotify file descriptor: %v", err)
+	}
+	return nil
+}
+
+func (i *Inotify) NumWatchers() int {
+	return len(i.Watchers)
+}
+
+func (i *Inotify) String() string {
+	if len(i.Watchers) < 20 {
+		dirs := make([]string, 0)
+		for _, w := range i.Watchers {
+			dirs = append(dirs, w.Dir)
+		}
+		return fmt.Sprintf("Watching: %v", dirs)
+	} else {
+		return fmt.Sprintf("Watching %d directories", len(i.Watchers))
+	}
+}