pubsub: Fix flaky unit test

Bug: 358132653
Change-Id: I0166090b786c7e0b68d3ced6fc79841c769ada9d
Reviewed-on: https://pigweed-internal-review.git.corp.google.com/c/pigweed/showcase/rp2/+/74409
Reviewed-by: Wyatt Hepler <hepler@google.com>
Pigweed-Auto-Submit: Aaron Green <aarongreen@google.com>
Commit-Queue: Aaron Green <aarongreen@google.com>
diff --git a/modules/pubsub/pubsub_test.cc b/modules/pubsub/pubsub_test.cc
index f300e60..750f8c3 100644
--- a/modules/pubsub/pubsub_test.cc
+++ b/modules/pubsub/pubsub_test.cc
@@ -36,10 +36,10 @@
  public:
   void SetNotifyAfter(size_t num_events) PW_LOCKS_EXCLUDED(lock_) {
     std::lock_guard lock(lock_);
-    if (num_events < events_seen_) {
+    if (num_events <= events_seen_) {
       notification_.release();
+      events_seen_ = 0;
     }
-    events_seen_ = 0;
     notify_after_ = num_events;
   }