Fix issue in async generator wrapper

Author: TimPansino

newrelic/common/async_wrapper.py

@@ -93,7 +93,7 @@ async def wrapper(*args, **kwargs):
         with trace:
             while True:
                 try:
-                    g.asend(value).send(None)
+                    yielded = await g.asend(value)
                 except StopAsyncIteration as e:
                     # The underlying async generator has finished, return propagates a new StopAsyncIteration
                     return
@@ -107,7 +107,7 @@ async def wrapper(*args, **kwargs):
                     # An exception was thrown with .athrow(), propagate to the original async generator.
                     # Return value logic must be identical to .asend()
                     try:
-                        g.athrow(type(e), e).send(None)
+                        value = yield await g.athrow(type(e), e)
                     except StopAsyncIteration as e:
                         # The underlying async generator has finished, return propagates a new StopAsyncIteration
                         return

tests/agent_features/_test_async_generator_trace.py

@@ -260,6 +260,37 @@ async def _test():
     assert full_metrics[key].total_exclusive_call_time < 0.2
 
 
+@validate_transaction_metrics(
+    "test_asend_receives_a_value",
+    background_task=True,
+    scoped_metrics=[("Function/agen", 1)],
+    rollup_metrics=[("Function/agen", 1)],
+)
+def test_asend_receives_a_value(event_loop):
+    _received = []
+    @function_trace(name="agen")
+    async def agen():
+        value = yield
+        _received.append(value)
+        yield value
+
+    @background_task(name="test_asend_receives_a_value")
+    async def _test():
+        gen = agen()
+
+        # kickstart the coroutine
+        await anext(gen)
+
+        assert await gen.asend("foobar") == "foobar"
+        assert _received and _received[0] == "foobar"
+
+        # finish consumption of the coroutine if necessary
+        async for _ in gen:
+            pass
+
+    event_loop.run_until_complete(_test())
+
+
 @validate_transaction_metrics(
     "test_athrow_yields_a_value",
     background_task=True,