And fix trio test.

Author: Carreau

ipykernel/kernelapp.py

@@ -730,15 +730,23 @@ def initialize(self, argv=None):
         sys.stdout.flush()
         sys.stderr.flush()
 
-    def start(self) -> None:
-        """Start the application."""
+    async def _start(self) -> None:
+        """
+        Async version of start, when the loop is not controlled by IPykernel
+
+        For example to be used in test suite with @pytest.mark.trio
+        """
         if self.subapp is not None:
             self.subapp.start()
-            return
+            return None
         if self.poller is not None:
             self.poller.start()
+        return await self.main()
+
+    def start(self) -> None:
+        """Start the application."""
         backend = "trio" if self.trio_loop else "asyncio"
-        run(self.main, backend=backend)
+        run(self._start, backend=backend)
         return
 
     async def _wait_to_enter_eventloop(self):

pyproject.toml

@@ -54,14 +54,15 @@ docs = [
   "trio"
 ]
 test = [
-    "pytest>=7.0,<9",
-    "pytest-cov",
     "flaky",
     "ipyparallel",
     "pre-commit",
+    "pytest-asyncio>=0.23.5",
+    "pytest-cov",
     "pytest-timeout",
+    "pytest-trio",
+    "pytest>=7.0,<9",
     "trio",
-    "pytest-asyncio>=0.23.5",
 ]
 cov = [
   "coverage[toml]",

tests/test_ipkernel_direct.py

@@ -1,6 +1,5 @@
 """Test IPythonKernel directly"""
 
-import asyncio
 import os
 
 import pytest

tests/test_kernel_direct.py

@@ -3,9 +3,7 @@
 # Copyright (c) IPython Development Team.
 # Distributed under the terms of the Modified BSD License.
 
-import asyncio
 import os
-import warnings
 
 import pytest
 

tests/test_kernelapp.py

@@ -117,23 +117,19 @@ def test_merge_connection_file():
         os.remove(cf)
 
 
-# FIXME: @pytest.mark.skipif(trio is None, reason="requires trio")
-@pytest.mark.skip(
-    "Cant run under pytest-trio as IPKernelApp is the one starting the loop"
-)
-def test_trio_loop():
+@pytest.mark.trio()
+async def test_trio_loop():
     app = IPKernelApp(trio_loop=True)
 
-    def trigger_stop():
-        time.sleep(1)
+    async def trigger_stop():
+        await trio.sleep(1)
         app.stop()
 
-    thread = threading.Thread(target=trigger_stop)
-    thread.start()
-
     app.kernel = MockKernel()
     app.init_sockets()
-    app.start()
+    async with trio.open_nursery() as nursery:
+        nursery.start_soon(app._start)
+        nursery.start_soon(trigger_stop)
     app.cleanup_connection_file()
     app.kernel.destroy()
     app.close()