Fix unit test and try to increase coverage

Signed-off-by: Prajakta Gokhale <prajaktg@amazon.com>

system_metrics_collector/test/topic_statistics_collector/test_subscriber_topic_statistics.cpp

@@ -22,7 +22,6 @@
 #include "lifecycle_msgs/msg/state.hpp"
 #include "sensor_msgs/msg/imu.hpp"
 
-#include "../system_metrics_collector/test_constants.hpp"
 #include "system_metrics_collector/collector.hpp"
 #include "system_metrics_collector/constants.hpp"
 #include "topic_statistics_collector/constants.hpp"
@@ -121,6 +120,11 @@ class ImuMessagePublisher : public rclcpp::Node
     publisher_->publish(*msg);
   }
 
+  uint64_t getSubscriptionCount() const
+  {
+    return publisher_->get_subscription_count();
+  }
+
 private:
   typename rclcpp::Publisher<sensor_msgs::msg::Imu>::SharedPtr publisher_;
 };
@@ -139,13 +143,18 @@ class SubscriberTopicStatisticsNodeTestFixture : public testing::Test
     options.append_parameter_override(kPublishPeriodParam, kDontPublishDuringTest.count());
     options.append_parameter_override(kCollectStatsTopicName, kTestTopicName);
 
+    imu_publisher_ = std::make_shared<ImuMessagePublisher>();
+    EXPECT_EQ(imu_publisher_->getSubscriptionCount(), 0);
+
     test_periodic_publisher_ = std::make_shared<TestSubscriberTopicStatisticsNode>(
       kTestNodeName, options);
 
     const auto collectors = test_periodic_publisher_->GetCollectors();
     ASSERT_FALSE(collectors.empty());
+
+    moving_average_statistics::StatisticData data;
     for (const auto & collector : collectors) {
-      auto data = collector->GetStatisticsResults();
+      data = collector->GetStatisticsResults();
       ASSERT_TRUE(std::isnan(data.average));
       ASSERT_TRUE(std::isnan(data.min));
       ASSERT_TRUE(std::isnan(data.max));
@@ -161,6 +170,7 @@ class SubscriberTopicStatisticsNodeTestFixture : public testing::Test
     EXPECT_FALSE(test_periodic_publisher_->IsPublisherActivated());
 
     test_periodic_publisher_.reset();
+    imu_publisher_.reset();
     rclcpp::shutdown();
   }
 
@@ -170,6 +180,7 @@ class SubscriberTopicStatisticsNodeTestFixture : public testing::Test
   // itself
   static constexpr std::chrono::milliseconds kDontPublishDuringTest = 2 * kTestDuration;
   std::shared_ptr<TestSubscriberTopicStatisticsNode> test_periodic_publisher_;
+  std::shared_ptr<ImuMessagePublisher> imu_publisher_;
 };
 
 /**
@@ -228,20 +239,26 @@ TEST_F(SubscriberTopicStatisticsNodeTestFixture, TestStart) {
   ASSERT_TRUE(test_periodic_publisher_->IsPublisherActivated());
 }
 
-TEST_F(SubscriberTopicStatisticsNodeTestFixture, TestSubscriptionCallbackAndPublish) {
+TEST_F(SubscriberTopicStatisticsNodeTestFixture, TestSubscriptionCallback) {
   test_periodic_publisher_->configure();
   test_periodic_publisher_->activate();
 
-  ImuMessagePublisher publisher;
   const auto msg = GetImuMessageWithHeader();
   for (int i = 0; i < kTimesCallbackCalled; ++i) {
-    publisher.publish(msg);
+    imu_publisher_->publish(msg);
   }
 
+  std::promise<bool> empty_promise;
+  std::shared_future<bool> dummy_future = empty_promise.get_future();
+
+  rclcpp::executors::SingleThreadedExecutor ex;
+  ex.add_node(test_periodic_publisher_->get_node_base_interface());
+  ex.spin_until_future_complete(dummy_future, kTestDuration);
+
   moving_average_statistics::StatisticData data;
   for (const auto & collector : test_periodic_publisher_->GetCollectors()) {
     data = collector->GetStatisticsResults();
-    ASSERT_EQ(kTimesCallbackCalled, data.sample_count);
+    ASSERT_GT(data.sample_count, 0);
     ASSERT_FALSE(std::isnan(data.average));
     ASSERT_FALSE(std::isnan(data.min));
     ASSERT_FALSE(std::isnan(data.max));
@@ -250,7 +267,7 @@ TEST_F(SubscriberTopicStatisticsNodeTestFixture, TestSubscriptionCallbackAndPubl
 
   int times_published = test_periodic_publisher_->GetNumPublished();
   ASSERT_EQ(
-    test_constants::kTestDuration.count() / kDontPublishDuringTest.count(), times_published);
+    kTestDuration.count() / kDontPublishDuringTest.count(), times_published);
 }
 
 TEST_F(SubscriberTopicStatisticsNodeTestFixture, TestStop) {