1 files changed, 51 insertions, 0 deletions
diff --git a/rpc/client_test.go b/rpc/client_test.go
index 58dceada0..424d7f5bc 100644
--- a/rpc/client_test.go
+++ b/rpc/client_test.go
@@ -296,6 +296,57 @@ func TestClientSubscribeClose(t *testing.T) {
 	}
 }
 
+// This test checks that Client doesn't lock up when a single subscriber
+// doesn't read subscription events.
+func TestClientNotificationStorm(t *testing.T) {
+	server := newTestServer("eth", new(NotificationTestService))
+	defer server.Stop()
+
+	doTest := func(count int, wantError bool) {
+		client := DialInProc(server)
+		defer client.Close()
+		ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+		defer cancel()
+
+		// Subscribe on the server. It will start sending many notifications
+		// very quickly.
+		nc := make(chan int)
+		sub, err := client.EthSubscribe(nc, "someSubscription", count, 0)
+		if err != nil {
+			t.Fatal("can't subscribe:", err)
+		}
+		defer sub.Unsubscribe()
+
+		// Process each notification, try to run a call in between each of them.
+		for i := 0; i < count; i++ {
+			select {
+			case val := <-nc:
+				if val != i {
+					t.Fatalf("(%d/%d) unexpected value %d", i, count, val)
+				}
+			case err := <-sub.Err():
+				if wantError && err != ErrSubscriptionQueueOverflow {
+					t.Fatalf("(%d/%d) got error %q, want %q", i, count, err, ErrSubscriptionQueueOverflow)
+				} else if !wantError {
+					t.Fatalf("(%d/%d) got unexpected error %q", i, count, err)
+				}
+				return
+			}
+			var r int
+			err := client.CallContext(ctx, &r, "eth_echo", i)
+			if err != nil {
+				if !wantError {
+					t.Fatalf("(%d/%d) call error: %v", i, count, err)
+				}
+				return
+			}
+		}
+	}
+
+	doTest(8000, false)
+	doTest(10000, true)
+}
+
 func TestClientHTTP(t *testing.T) {
 	server := newTestServer("service", new(Service))
 	defer server.Stop()