fix: async_to_sync tests (#72)

* add async_to_sync test

* fix async_to_sync test

* extend async_to_sync tests

Author: stepansergeevitch

src/firebolt/common/util.py

@@ -1,4 +1,4 @@
-from asyncio import get_event_loop
+from asyncio import get_event_loop, new_event_loop
 from functools import lru_cache, wraps
 from typing import TYPE_CHECKING, Any, Callable, Type, TypeVar
 
@@ -39,6 +39,15 @@ def fix_url_schema(url: str) -> str:
 def async_to_sync(f: Callable) -> Callable:
     @wraps(f)
     def sync(*args: Any, **kwargs: Any) -> Any:
-        return get_event_loop().run_until_complete(f(*args, **kwargs))
+        close = False
+        try:
+            loop = get_event_loop()
+        except RuntimeError:
+            loop = new_event_loop()
+            close = True
+        res = loop.run_until_complete(f(*args, **kwargs))
+        if close:
+            loop.close()
+        return res
 
     return sync

tests/unit/common/__init__.py

@@ -0,0 +1,52 @@
+from asyncio import run
+from threading import Thread
+
+from pytest import raises
+
+from firebolt.common.util import async_to_sync
+
+
+def test_async_to_sync_happy_path():
+    """async_to_sync properly converts coroutine to sync function"""
+
+    class JobMarker(Exception):
+        pass
+
+    async def task():
+        raise JobMarker()
+
+    for i in range(3):
+        with raises(JobMarker):
+            async_to_sync(task)()
+
+
+def test_async_to_sync_thread():
+    """async_to_sync properly works in threads"""
+
+    marks = [False] * 3
+
+    async def task(id: int):
+        marks[id] = True
+
+    ts = [Thread(target=async_to_sync(task), args=[i]) for i in range(3)]
+    [t.start() for t in ts]
+    [t.join() for t in ts]
+    assert all(marks)
+
+
+def test_async_to_sync_after_run():
+    """async_to_sync properly runs after asyncio.run"""
+
+    class JobMarker(Exception):
+        pass
+
+    async def task():
+        raise JobMarker()
+
+    with raises(JobMarker):
+        run(task())
+
+    # Here local event loop is closed by run
+
+    with raises(JobMarker):
+        async_to_sync(task)()