try some more tsting

internal/fswatcher/inotify/sys/syscalls.go

@@ -0,0 +1,36 @@
+// +build linux
+
+package sys
+
+import (
+	"fmt"
+
+	"golang.org/x/sys/unix"
+)
+
+const events = unix.IN_ALL_EVENTS
+
+type InotifySyscallsUNIX struct{}
+
+func (isu *InotifySyscallsUNIX) Init() (int, error) {
+	fd, errno := unix.InotifyInit1(unix.IN_CLOEXEC)
+	if fd < 0 {
+		return fd, fmt.Errorf("errno: %d", errno)
+	}
+	return fd, nil
+}
+
+func (isu *InotifySyscallsUNIX) AddWatch(fd int, dir string) (int, error) {
+	wd, errno := unix.InotifyAddWatch(fd, dir, events)
+	if wd < 0 {
+		return wd, fmt.Errorf("errno: %d", errno)
+	}
+	return wd, nil
+}
+
+func (isu *InotifySyscallsUNIX) Close(fd int) error {
+	if err := unix.Close(fd); err != nil {
+		return err
+	}
+	return nil
+}

internal/fswatcher/inotify/sys/syscalls_test.go

@@ -0,0 +1,45 @@
+// +build linux
+
+package sys
+
+import (
+	"testing"
+)
+
+func TestSyscalls(t *testing.T) {
+	is := &InotifySyscallsUNIX{}
+
+	fd, err := is.Init()
+	if err != nil {
+		t.Fatalf("Unexpected error for inotify init: %v", err)
+	}
+
+	_, err = is.AddWatch(fd, "testdata")
+	if err != nil {
+		t.Fatalf("Unexpected error adding watch to dir 'testdata': %v", err)
+	}
+
+	err = is.Close(fd)
+	if err != nil {
+		t.Fatalf("Unexpected error closing inotify: %v", err)
+	}
+}
+
+func TestSyscallsError(t *testing.T) {
+	is := &InotifySyscallsUNIX{}
+
+	fd, err := is.Init()
+	if err != nil {
+		t.Fatalf("Unexpected error for inotify init: %v", err)
+	}
+
+	_, err = is.AddWatch(fd, "non-existing-dir")
+	if err == nil || err.Error() != "errno: 2" {
+		t.Fatalf("Expected errno 2 for non-existing-dir but got: %v", err)
+	}
+
+	err = is.Close(fd)
+	if err != nil {
+		t.Fatalf("Unexpected error closing inotify: %v", err)
+	}
+}