import unittest
import launch
import launch.actions
import launch_ros.actions
import launch_testing.actions
import launch_testing.markers
import pytest
import rclpy
from rclpy.node import Node
from std_msgs.msg import String

from launch_testing_ros import WaitForTopics

def generate_node(i):
    return launch_ros.actions.Node(
        executable='talker',
        package='demo_nodes_cpp',
        name='demo_node_' + str(i),
        remappings = [('chatter', 'chatter_' + str(i))]
    )

@pytest.mark.launch_test
@launch_testing.markers.keep_alive
def generate_test_description():
    # 'n' changes the number of nodes and topics
    n = 5
    description = [generate_node(i) for i in range(n)] + [launch_testing.actions.ReadyToTest()]
    return launch.LaunchDescription(description), {'count':n}

class TestFixture(unittest.TestCase):

    def test_check_if_msgs_published(self, proc_output, count):

        topic_list = [('chatter_' + str(i), String) for i in range(count)]
        with WaitForTopics(topic_list, timeout=5.0):
            print("The topics are alive !")