Add active waitForMesh proc.

tests/pubsub/utils.nim

@@ -147,6 +147,12 @@ proc subscribeRandom*(nodes: seq[PubSub]) {.async.} =
           await dialer.switch.connect(node.peerInfo.peerId, node.peerInfo.addrs)
           dialed.add(node.peerInfo.peerId)
 
+proc activeWait(
+    interval: Duration, maximum: Moment, timeoutErrorMessage = "Timeout on activeWait"
+) {.async.} =
+  await sleepAsync(interval)
+  doAssert Moment.now() < maximum, timeoutErrorMessage
+
 proc waitSub*(sender, receiver: auto, key: string) {.async.} =
   if sender == receiver:
     return
@@ -201,3 +207,19 @@ proc waitSubGraph*(nodes: seq[PubSub], key: string) {.async.} =
 
     await sleepAsync(5.milliseconds)
     doAssert Moment.now() < timeout, "waitSubGraph timeout!"
+
+proc waitForMesh*(
+    sender: auto, receiver: auto, key: string, timeoutDuration = 5.seconds
+) {.async.} =
+  if sender == receiver:
+    return
+
+  let
+    timeoutMoment = Moment.now() + timeoutDuration
+    gossipsubSender = GossipSub(sender)
+    receiverPeerId = receiver.peerInfo.peerId
+
+  while not gossipsubSender.mesh.hasPeerId(key, receiverPeerId):
+    trace "waitForMesh sleeping..."
+    await activeWait(5.milliseconds, timeoutMoment, "waitForMesh timeout!")
+  echo "waitForMesh done!"