watch_test.go

package whatnot

import (
	"testing"
	"time"

	"github.com/stretchr/testify/assert"
)

func TestWatchNotifications(t *testing.T) {
	t.Run("Create new watch subscription on PathElement", createNewWatchOnElement)
	t.Run("Changing a path element creates notification", changeElementAndNotify)
}

func createNewWatchOnElement(t *testing.T) {
	t.Log("creating a new watch on existing path element")

	gns := createTestNamespace(t)
	testPathString := PathString("/path/to/test/data")
	testpath := testPathString.ToAbsolutePath()
	err := gns.RegisterAbsolutePath(testpath)
	if !assert.Nil(t, err, "registerabsolute path returned error") {
		t.Error(err.Error())
		return
	}

	elem := gns.FetchAbsolutePath(testPathString)

	sub := elem.SubscribeToEvents(false)
	select {
	case <-sub.Events():
	default:
		// we instantly pass here, because there is no waiting message on the channel
	}

}

func changeElementAndNotify(t *testing.T) {
	t.Log("testing that a notification is received when modifying a watched element")
	gns := createTestNamespace(t)

	testPathString := PathString("/path/to/test/data")
	testpath := testPathString.ToAbsolutePath()
	err := gns.RegisterAbsolutePath(testpath)
	if !assert.Nil(t, err, "registerabsolute path returned error") {
		t.Error(err.Error())
		return
	}

	t.Log("Creating a subscription to change notifications on the test element")
	elem := gns.FetchAbsolutePath(testPathString)
	// create a local subscription to the element itself
	elemsub := elem.SubscribeToEvents(false)

	parentelement := elem.Parent()
	// create a prefix subscription to the parent element, which should also receive the same notification
	parsub := parentelement.SubscribeToEvents(true)

	go func() {
		t.Log("waiting 1 second for notifier channel to attach")
		time.Sleep(time.Second)
		t.Log("locking the element to create a change notification")
		elem.Lock()
	}()

	e := <-elemsub.Events()
	t.Logf("received update event %d from element subscription", e.id)
	assert.Equal(t, elem, e.OnElement(), "watch event did not indicate original element")

	e = <-parsub.Events()
	t.Logf("received update event %d from parent element subscription", e.id)
	assert.Equal(t, elem, e.OnElement(), "watch event did not indicate original element")

	time.Sleep(time.Second)

}