text: // Copyright (C) 2018, 2019 Kevin Hallenbeck, Joshua Whitley
  // All rights reserved.
  //
  // Software License Agreement (BSD License 2.0)
  //
  // Redistribution and use in source and binary forms, with or without
  // modification, are permitted provided that the following conditions
  // are met:
  //
  //  * Redistributions of source code must retain the above copyright
  //    notice, this list of conditions and the following disclaimer.
  //  * Redistributions in binary form must reproduce the above
  //    copyright notice, this list of conditions and the following
  //    disclaimer in the documentation and/or other materials provided
  //    with the distribution.
  //  * Neither the name of {copyright_holder} nor the names of its
  //    contributors may be used to endorse or promote products derived
  //    from this software without specific prior written permission.
  //
  // THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
  // "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
  // LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
  // FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE
  // COPYRIGHT OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT,
  // INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING,
  // BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
  // LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
  // CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  // LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN
  // ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  // POSSIBILITY OF SUCH DAMAGE.
  
  #include <gtest/gtest.h>
  
  #include <ros/ros.h>
  #include <sensor_msgs/PointCloud2.h>
  #include <sensor_msgs/LaserScan.h>
  
  // Subscriber receive callback
  void recv(const sensor_msgs::LaserScanConstPtr& msg) {}
  
  // Build and publish a minimal PointCloud2 message
  void publish(const ros::Publisher &pub)
  {
    const uint32_t POINT_STEP = 32;
    sensor_msgs::PointCloud2 msg;
    msg.header.frame_id = "";
    msg.header.stamp = ros::Time::now();
    msg.fields.resize(5);
    msg.fields[0].name = "x";
    msg.fields[0].offset = 0;
    msg.fields[0].datatype = sensor_msgs::PointField::FLOAT32;
    msg.fields[0].count = 1;
    msg.fields[1].name = "y";
    msg.fields[1].offset = 4;
    msg.fields[1].datatype = sensor_msgs::PointField::FLOAT32;
    msg.fields[1].count = 1;
    msg.fields[2].name = "z";
    msg.fields[2].offset = 8;
    msg.fields[2].datatype = sensor_msgs::PointField::FLOAT32;
    msg.fields[2].count = 1;
    msg.fields[3].name = "intensity";
    msg.fields[3].offset = 16;
    msg.fields[3].datatype = sensor_msgs::PointField::FLOAT32;
    msg.fields[3].count = 1;
    msg.fields[4].name = "ring";
    msg.fields[4].offset = 20;
    msg.fields[4].datatype = sensor_msgs::PointField::UINT16;
    msg.fields[4].count = 1;
    msg.data.resize(1 * POINT_STEP, 0x00);
    msg.point_step = POINT_STEP;
    msg.row_step = msg.data.size();
    msg.height = 1;
    msg.width = msg.row_step / POINT_STEP;
    msg.is_bigendian = false;
    msg.is_dense = true;
    pub.publish(msg);
  }
  
  // Verify correct handling of subscribe and unsubscribe events
  TEST(Main, subscribe_unsubscribe)
  {
    ros::NodeHandle nh;
    ros::Publisher pub = nh.advertise<sensor_msgs::PointCloud2>("velodyne_points", 2);
  
    // Wait for node to startup
    ros::WallDuration(2.0).sleep();
    ros::spinOnce();
    EXPECT_EQ(0, pub.getNumSubscribers());
  
    // Subscribe to 'scan' and expect the node to subscribe to 'velodyne_points'
    ros::Subscriber sub = nh.subscribe("scan", 2, recv);
  
    for (size_t i = 10; i > 0; i--)
    {
      publish(pub);
      ros::WallDuration(0.1).sleep();
      ros::spinOnce();
    }
  
    EXPECT_EQ(1, sub.getNumPublishers());
    EXPECT_EQ(1, pub.getNumSubscribers());
  
    // Unsubscribe from 'scan' and expect the node to unsubscribe from 'velodyne_points'
    sub.shutdown();
  
    for (size_t i = 10; i > 0; i--)
    {
      publish(pub);
      ros::WallDuration(0.1).sleep();
      ros::spinOnce();
    }
  
    EXPECT_EQ(0, sub.getNumPublishers());
    EXPECT_EQ(0, pub.getNumSubscribers());
  }
  
  // Run all the tests that were declared with TEST()
  int main(int argc, char **argv)
  {
    testing::InitGoogleTest(&argc, argv);
    ros::init(argc, argv, "test_lazy_subscriber");
    return RUN_ALL_TESTS();
  }
  