text: ///////////////////////////////////////////////////////////////////////////////
  // Copyright (C) 2017, PAL Robotics.
  //
  // 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 PAL Robotics, Inc. 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
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  // ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
  // POSSIBILITY OF SUCH DAMAGE.
  //////////////////////////////////////////////////////////////////////////////
  
  /// \author Jeremie Deray
  
  #include "test_common.h"
  
  // TEST CASES
  TEST_F(DiffDriveControllerTest, testCmdVelOutTopic)
  {
  	// wait for ROS
  	while (!isControllerAlive())
  	{
  		ros::Duration(0.1).sleep();
  	}
  
  	EXPECT_TRUE(isPublishingCmdVelOut());
  
  	// zero everything before test
  	geometry_msgs::Twist cmd_vel;
  	cmd_vel.linear.x = 0.0;
  	cmd_vel.angular.z = 0.0;
  	publish(cmd_vel);
  	ros::Duration(0.1).sleep();
  
  	cmd_vel.linear.x = 0.1;
  	publish(cmd_vel);
  	ros::Duration(0.1).sleep();
  
  	EXPECT_TRUE(isPublishingCmdVelOut());
  
  	// get a twist message
  	geometry_msgs::TwistStamped odom_msg = getLastCmdVelOut();
  
  	EXPECT_GT(fabs(odom_msg.twist.linear.x), 0);
  }
  
  int main(int argc, char **argv)
  {
  	testing::InitGoogleTest(&argc, argv);
  	ros::init(argc, argv, "diff_drive_pub_cmd_vel_out_topic_test");
  
  	ros::AsyncSpinner spinner(1);
  	spinner.start();
  	int ret = RUN_ALL_TESTS();
  	spinner.stop();
  	ros::shutdown();
  	return ret;
  }
  