Fix launch fixture setup hanging before readiness

launch_pytest/launch_pytest/plugin.py

@@ -128,9 +128,17 @@ def pytest_fixture_setup(fixturedef, request):
         ))
         ready = get_ready_to_test_action(ld)
         asyncio.set_event_loop(event_loop)
-        event = asyncio.Event()
-        ready._add_callback(lambda: event.set())
-        run_until_complete(event_loop, event.wait())
+        ready_future = event_loop.create_future()
+
+        def wakeup(is_ready):
+            if not ready_future.done():
+                ready_future.set_result(is_ready)
+
+        ready._add_callback(functools.partial(wakeup, True))
+        run_async_task.add_done_callback(lambda _: wakeup(False))
+        run_until_complete(event_loop, ready_future)
+        if not ready_future.result():
+            fail(f'{eprefix} launch service stopped before ReadyToTest')
         # this is guaranteed by the current run_async() implementation, let's check it just in case
         # it changes in the future
         assert ls.event_loop is event_loop

launch_pytest/test/launch_pytest/test_plugin.py

@@ -15,6 +15,55 @@
 from pathlib import Path
 import shutil
 
+import pytest
+
+
+@pytest.mark.parametrize('action', [
+    "IncludeLaunchDescription(PythonLaunchDescriptionSource('missing.launch.py'))",
+    "GroupAction(actions=[ReadyToTest()], condition=IfCondition('false'))",
+])
+def test_launch_service_stops_before_ready(testdir, action):
+    testdir.makepyfile(f"""\
+from launch import LaunchDescription
+from launch.actions import GroupAction, IncludeLaunchDescription
+from launch.conditions import IfCondition
+from launch.launch_description_sources import PythonLaunchDescriptionSource
+import launch_pytest
+from launch_pytest.actions import ReadyToTest
+import pytest
+
+@launch_pytest.fixture
+def launch_description():
+    return LaunchDescription([{action}])
+
+@pytest.mark.launch(fixture=launch_description)
+def test_case():
+    pytest.fail('test body must not run before ReadyToTest')
+""")
+    result = testdir.runpytest_subprocess(timeout=10)
+    result.assert_outcomes(errors=1)
+    result.stdout.fnmatch_lines(['*launch service stopped before ReadyToTest*'])
+
+
+def test_launch_fixture_waits_for_delayed_ready(testdir):
+    testdir.makepyfile("""\
+from launch import LaunchDescription
+from launch.actions import TimerAction
+import launch_pytest
+from launch_pytest.actions import ReadyToTest
+import pytest
+
+@launch_pytest.fixture
+def launch_description():
+    return LaunchDescription([TimerAction(period=0.01, actions=[ReadyToTest()])])
+
+@pytest.mark.launch(fixture=launch_description)
+def test_case():
+    pass
+""")
+    result = testdir.runpytest_subprocess(timeout=10)
+    result.assert_outcomes(passed=1)
+
 
 def test_launch_fixture_is_not_a_launch_description(testdir):
     testdir.makepyfile("""\