Copy async_lru for Python 3.7 compatibility

tests/external/test_exception.py

@@ -0,0 +1,48 @@
+import asyncio
+
+import pytest
+from great_ai.external.async_lru import alru_cache
+
+pytestmark = pytest.mark.asyncio
+
+
+async def test_alru_cache_exception(check_lru, loop):
+    @alru_cache(cache_exceptions=True)
+    async def coro(val):
+        1 / 0
+
+    inputs = [1, 1, 1]
+    coros = [coro(v) for v in inputs]
+
+    ret = await asyncio.gather(*coros, return_exceptions=True)
+
+    check_lru(coro, hits=2, misses=1, cache=1, tasks=0)
+
+    for item in ret:
+        assert isinstance(item, ZeroDivisionError)
+
+    with pytest.raises(ZeroDivisionError):
+        await coro(1)
+
+    check_lru(coro, hits=3, misses=1, cache=1, tasks=0)
+
+
+async def test_alru_not_cache_exception(check_lru, loop):
+    @alru_cache(cache_exceptions=False)
+    async def coro(val):
+        1 / 0
+
+    inputs = [1, 1, 1]
+    coros = [coro(v) for v in inputs]
+
+    ret = await asyncio.gather(*coros, return_exceptions=True)
+
+    check_lru(coro, hits=2, misses=1, cache=1, tasks=0)
+
+    for item in ret:
+        assert isinstance(item, ZeroDivisionError)
+
+    with pytest.raises(ZeroDivisionError):
+        await coro(1)
+
+    check_lru(coro, hits=2, misses=2, cache=1, tasks=0)