snapshot of https://github.com/grpc/grpc-go.git (master, 2026-09-15; blobs > 131072B omitted)

internal/grpcsync/pubsub_test.go

@@ -0,0 +1,196 @@
+/*
+ *
+ * Copyright 2023 gRPC authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ *
+ */
+
+package grpcsync
+
+import (
+	"context"
+	"sync"
+	"testing"
+	"time"
+)
+
+type testSubscriber struct {
+	onMsgCh chan int
+}
+
+func newTestSubscriber(chSize int) *testSubscriber {
+	return &testSubscriber{onMsgCh: make(chan int, chSize)}
+}
+
+func (ts *testSubscriber) OnMessage(msg any) {
+	select {
+	case ts.onMsgCh <- msg.(int):
+	default:
+	}
+}
+
+func (s) TestPubSub_PublishNoMsg(t *testing.T) {
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+	pubsub := NewPubSub(ctx)
+
+	ts := newTestSubscriber(1)
+	pubsub.Subscribe(ts)
+
+	select {
+	case <-ts.onMsgCh:
+		t.Fatal("Subscriber callback invoked when no message was published")
+	case <-time.After(defaultTestShortTimeout):
+	}
+}
+
+func (s) TestPubSub_PublishMsgs_RegisterSubs_And_Stop(t *testing.T) {
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+	pubsub := NewPubSub(ctx)
+
+	const numPublished = 10
+
+	ts1 := newTestSubscriber(numPublished)
+	pubsub.Subscribe(ts1)
+
+	var wg sync.WaitGroup
+	wg.Add(2)
+	// Publish ten messages on the pubsub and ensure that they are received in order by the subscriber.
+	go func() {
+		for i := 0; i < numPublished; i++ {
+			pubsub.Publish(i)
+		}
+		wg.Done()
+	}()
+
+	go func() {
+		defer wg.Done()
+		for i := 0; i < numPublished; i++ {
+			select {
+			case m := <-ts1.onMsgCh:
+				if m != i {
+					t.Errorf("Received unexpected message: %q; want: %q", m, i)
+					return
+				}
+			case <-time.After(defaultTestTimeout):
+				t.Error("Timeout when expecting the onMessage() callback to be invoked")
+				return
+			}
+		}
+	}()
+	wg.Wait()
+	if t.Failed() {
+		t.FailNow()
+	}
+
+	// Register another subscriber and ensure that it receives the last published message.
+	ts2 := newTestSubscriber(numPublished)
+	pubsub.Subscribe(ts2)
+
+	select {
+	case m := <-ts2.onMsgCh:
+		if m != numPublished-1 {
+			t.Fatalf("Received unexpected message: %q; want: %q", m, numPublished-1)
+		}
+	case <-time.After(defaultTestShortTimeout):
+		t.Fatal("Timeout when expecting the onMessage() callback to be invoked")
+	}
+
+	wg.Add(3)
+	// Publish ten messages on the pubsub and ensure that they are received in order by the subscribers.
+	go func() {
+		for i := 0; i < numPublished; i++ {
+			pubsub.Publish(i)
+		}
+		wg.Done()
+	}()
+	go func() {
+		defer wg.Done()
+		for i := 0; i < numPublished; i++ {
+			select {
+			case m := <-ts1.onMsgCh:
+				if m != i {
+					t.Errorf("Received unexpected message: %q; want: %q", m, i)
+					return
+				}
+			case <-time.After(defaultTestTimeout):
+				t.Error("Timeout when expecting the onMessage() callback to be invoked")
+				return
+			}
+		}
+
+	}()
+	go func() {
+		defer wg.Done()
+		for i := 0; i < numPublished; i++ {
+			select {
+			case m := <-ts2.onMsgCh:
+				if m != i {
+					t.Errorf("Received unexpected message: %q; want: %q", m, i)
+					return
+				}
+			case <-time.After(defaultTestTimeout):
+				t.Error("Timeout when expecting the onMessage() callback to be invoked")
+				return
+			}
+		}
+	}()
+	wg.Wait()
+	if t.Failed() {
+		t.FailNow()
+	}
+
+	cancel()
+	<-pubsub.Done()
+
+	go func() {
+		pubsub.Publish(99)
+	}()
+	// Ensure that the subscriber callback is not invoked as instantiated
+	// pubsub has already closed.
+	select {
+	case <-ts1.onMsgCh:
+		t.Fatal("The callback was invoked after pubsub being stopped")
+	case <-ts2.onMsgCh:
+		t.Fatal("The callback was invoked after pubsub being stopped")
+	case <-time.After(defaultTestShortTimeout):
+	}
+}
+
+func (s) TestPubSub_PublishMsgs_BeforeRegisterSub(t *testing.T) {
+	ctx, cancel := context.WithTimeout(context.Background(), defaultTestTimeout)
+	defer cancel()
+	pubsub := NewPubSub(ctx)
+
+	const numPublished = 3
+	for i := 0; i < numPublished; i++ {
+		pubsub.Publish(i)
+	}
+
+	ts := newTestSubscriber(numPublished)
+	pubsub.Subscribe(ts)
+
+	// Ensure that the subscriber callback is invoked with a previously
+	// published message.
+	select {
+	case d := <-ts.onMsgCh:
+		if d != numPublished-1 {
+			t.Fatalf("Unexpected message received: %q; %q", d, numPublished-1)
+		}
+
+	case <-time.After(defaultTestShortTimeout):
+		t.Fatal("Timeout when expecting the onMessage() callback to be invoked")
+	}
+}