From 72e6f93a790546c2a8871f596ddb14b5200b510b Mon Sep 17 00:00:00 2001
From: rmorshea <ryan.morshead@gmail.com>
Date: Sun, 13 Sep 2020 13:53:54 -0700
Subject: [PATCH] test dispatcher start and stop

---
 idom/client/app/package-lock.json  |  2 +-
 idom/core/dispatcher.py            | 14 ++++-----
 tests/test_core/test_dispatcher.py | 50 +++++++++++++++++++++++++++++-
 3 files changed, 57 insertions(+), 9 deletions(-)

diff --git a/idom/client/app/package-lock.json b/idom/client/app/package-lock.json
index ecc4cafda..d71b84e58 100644
--- a/idom/client/app/package-lock.json
+++ b/idom/client/app/package-lock.json
@@ -1,6 +1,6 @@
 {
   "name": "idom-client-react",
-  "version": "0.4.1",
+  "version": "0.4.2",
   "lockfileVersion": 1,
   "requires": true,
   "dependencies": {
diff --git a/idom/core/dispatcher.py b/idom/core/dispatcher.py
index 2b3c86f0d..cfe4c5c14 100644
--- a/idom/core/dispatcher.py
+++ b/idom/core/dispatcher.py
@@ -26,6 +26,13 @@ def __init__(self, layout: Layout) -> None:
         super().__init__()
         self._layout = layout
 
+    async def start(self) -> None:
+        await self.__aenter__()
+
+    async def stop(self) -> None:
+        await self.task_group.cancel_scope.cancel()
+        await self.__aexit__(None, None, None)
+
     @async_resource
     async def layout(self) -> AsyncIterator[Layout]:
         async with self._layout as layout:
@@ -99,13 +106,6 @@ def __init__(self, layout: Layout) -> None:
         self._model_state: Any = {}
         self._update_queues: Dict[str, asyncio.Queue[LayoutUpdate]] = {}
 
-    async def start(self) -> None:
-        await self.__aenter__()
-
-    async def stop(self):
-        self.task_group.cancel_scope.cancel()
-        await self.__aexit__(None, None, None)
-
     @async_resource
     async def task_group(self) -> AsyncIterator[TaskGroup]:
         async with create_task_group() as group:
diff --git a/tests/test_core/test_dispatcher.py b/tests/test_core/test_dispatcher.py
index 685613014..43d874edd 100644
--- a/tests/test_core/test_dispatcher.py
+++ b/tests/test_core/test_dispatcher.py
@@ -6,7 +6,11 @@
 
 import idom
 from idom.core.layout import Layout, LayoutEvent
-from idom.core.dispatcher import SharedViewDispatcher, AbstractDispatcher
+from idom.core.dispatcher import (
+    SharedViewDispatcher,
+    AbstractDispatcher,
+    SingleViewDispatcher,
+)
 
 
 async def test_shared_state_dispatcher():
@@ -120,3 +124,47 @@ async def recv():
     with pytest.raises(ExceptionGroup, match="this is a bug"):
         async with DispatcherWithBug(idom.Layout(AnyElement())) as dispatcher:
             await dispatcher.run(send, recv, None)
+
+
+async def test_dispatcher_start_stop():
+    cancelled_recv = False
+    cancelled_send = False
+
+    async def send(patch):
+        nonlocal cancelled_send
+        try:
+            await asyncio.sleep(100)
+        except asyncio.CancelledError:
+            cancelled_send = True
+            raise
+        else:
+            assert False, "this should never be reached"
+
+    async def recv():
+        nonlocal cancelled_recv
+        try:
+            await asyncio.sleep(100)
+        except asyncio.CancelledError:
+            cancelled_recv = True
+            raise
+        else:
+            assert False, "this should never be reached"
+
+    @idom.element
+    def AnElement():
+        return idom.html.div()
+
+    dispatcher = SingleViewDispatcher(Layout(AnElement()))
+
+    await dispatcher.start()
+
+    await dispatcher.run(send, recv, None)
+
+    # let it run until it hits the sleeping recv/send calls
+    for i in range(10):
+        await asyncio.sleep(0)
+
+    await dispatcher.stop()
+
+    assert cancelled_recv
+    assert cancelled_send