feat(extension): expose host version and WebView page events

pkg/download/engine/webview/events_test.go

@@ -0,0 +1,52 @@
+package webview
+
+import (
+	"reflect"
+	"sync"
+	"testing"
+)
+
+func TestEventHubLifecycle(t *testing.T) {
+	var hub EventHub
+	var got []string
+	hub.Emit(Event{Name: "load"}) // Never replay pre-registration events.
+	off, err := hub.On("load", func(Event) { got = append(got, "first") })
+	if err != nil {
+		t.Fatal(err)
+	}
+	_, _ = hub.On("load", func(Event) { got = append(got, "second") })
+	_, _ = hub.On("closed", func(e Event) {
+		got = append(got, e.Data["reason"].(string))
+		off() // Unsubscription from a callback must not deadlock.
+	})
+	hub.Emit(Event{Name: "load"})
+	off()
+	off()
+	hub.Emit(Event{Name: "load"})
+	hub.Emit(Event{Name: "closed", Data: map[string]any{"reason": "api"}})
+	hub.Emit(Event{Name: "load"})
+	hub.Emit(Event{Name: "closed"})
+	if !reflect.DeepEqual(got, []string{"first", "second", "second", "api"}) {
+		t.Fatal(got)
+	}
+	if len(hub.listeners) != 0 {
+		t.Fatal("closed page retained listeners")
+	}
+	if _, err := hub.On("load", func(Event) {}); err == nil {
+		t.Fatal("registration on closed page succeeded")
+	}
+}
+
+func TestEventHubConcurrentUnsubscribe(t *testing.T) {
+	var hub EventHub
+	off, _ := hub.On("load", func(Event) {})
+	var wg sync.WaitGroup
+	for i := 0; i < 20; i++ {
+		wg.Add(1)
+		go func() { defer wg.Done(); off(); hub.Emit(Event{Name: "load"}) }()
+	}
+	wg.Wait()
+	if _, err := hub.On("invalid", func(Event) {}); err == nil {
+		t.Fatal("accepted invalid event")
+	}
+}