contrib/asgi: fix outcome for 500 responses without exception

Set the outcome based on the status code of the http.response.start
ASGI message instead of relying only on the raise of an exception.

elasticapm/contrib/asgi.py

@@ -50,6 +50,7 @@ async def wrapped_send(message) -> None:
             await set_context(lambda: middleware.get_data_from_response(message, constants.TRANSACTION), "response")
             result = "HTTP {}xx".format(message["status"] // 100)
             elasticapm.set_transaction_result(result, override=False)
+            elasticapm.set_transaction_outcome(http_status_code=message["status"], override=False)
         await send(message)
 
     return wrapped_send

tests/contrib/asgi/app.py

@@ -59,3 +59,8 @@ async def boom() -> None:
 @app.route("/body")
 async def json():
     return jsonify({"hello": "world"})
+
+
+@app.route("/500", methods=["GET"])
+async def error():
+    return "KO", 500

tests/contrib/asgi/asgi_tests.py

@@ -66,6 +66,23 @@ async def test_transaction_span(instrumented_app, elasticapm_client):
     assert span["sync"] == False
 
 
+@pytest.mark.asyncio
+async def test_transaction_span(instrumented_app, elasticapm_client):
+    async with async_asgi_testclient.TestClient(instrumented_app) as client:
+        resp = await client.get("/500")
+        assert resp.status_code == 500
+        assert resp.text == "KO"
+
+    assert len(elasticapm_client.events[constants.TRANSACTION]) == 1
+    assert len(elasticapm_client.events[constants.SPAN]) == 0
+    transaction = elasticapm_client.events[constants.TRANSACTION][0]
+    assert transaction["name"] == "GET unknown route"
+    assert transaction["result"] == "HTTP 5xx"
+    assert transaction["outcome"] == "failure"
+    assert transaction["context"]["request"]["url"]["full"] == "/500"
+    assert transaction["context"]["response"]["status_code"] == 500
+
+
 @pytest.mark.asyncio
 async def test_transaction_ignore_url(instrumented_app, elasticapm_client):
     elasticapm_client.config.update("1", transaction_ignore_urls="/foo*")