Improve coroutine provider tests

tests/unit/providers/test_coroutines_py3.py

@@ -1,6 +1,7 @@
 """Dependency injector coroutine providers unit tests."""
 
 import asyncio
+from asyncio import coroutines, events, tasks
 
 import unittest2 as unittest
 
@@ -18,9 +19,48 @@ def _example(arg1, arg2, arg3, arg4):
     return arg1, arg2, arg3, arg4
 
 
-def _run(coro):
-    loop = asyncio.get_event_loop()
-    return loop.run_until_complete(coro)
+def _run(coro, debug=False):
+    if events._get_running_loop() is not None:
+        raise RuntimeError(
+            "asyncio.run() cannot be called from a running event loop")
+
+    if not coroutines.iscoroutine(coro):
+        raise ValueError("a coroutine was expected, got {!r}".format(coro))
+
+    loop = events.new_event_loop()
+    try:
+        events.set_event_loop(loop)
+        loop.set_debug(debug)
+        return loop.run_until_complete(coro)
+    finally:
+        try:
+            _cancel_all_tasks(loop)
+            loop.run_until_complete(loop.shutdown_asyncgens())
+        finally:
+            events.set_event_loop(None)
+            loop.close()
+
+
+def _cancel_all_tasks(loop):
+    to_cancel = tasks.all_tasks(loop)
+    if not to_cancel:
+        return
+
+    for task in to_cancel:
+        task.cancel()
+
+    loop.run_until_complete(
+        tasks.gather(*to_cancel, loop=loop, return_exceptions=True))
+
+    for task in to_cancel:
+        if task.cancelled():
+            continue
+        if task.exception() is not None:
+            loop.call_exception_handler({
+                'message': 'unhandled exception during asyncio.run() shutdown',
+                'exception': task.exception(),
+                'task': task,
+            })
 
 
 class CoroutineTests(unittest.TestCase):