Fix UnboundLocalError local variable 'start' referenced before assignment

CHANGELOG.md

@@ -7,6 +7,11 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## Unreleased
 
+### Fixed
+
+- `opentelemetry-instrumentation-asgi` Fix UnboundLocalError local variable 'start' referenced before assignment 
+ ([#1889](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1889))
+
 ## Version 1.19.0/0.40b0 (2023-07-13)
 - `opentelemetry-instrumentation-asgi` Add `http.server.request.size` metric
  ([#1867](https://github.com/open-telemetry/opentelemetry-python-contrib/pull/1867))

instrumentation/opentelemetry-instrumentation-asgi/src/opentelemetry/instrumentation/asgi/__init__.py

@@ -538,6 +538,7 @@ async def __call__(self, scope, receive, send):
  receive: An awaitable callable yielding dictionaries
  send: An awaitable callable taking a single dictionary as argument.
  """
+ start = default_timer()
  if scope["type"] not in ("http", "websocket"):
  return await self.app(scope, receive, send)
 
@@ -591,7 +592,6 @@ async def __call__(self, scope, receive, send):
  send,
  duration_attrs,
  )
- start = default_timer()
 
  await self.app(scope, otel_receive, otel_send)
  finally:

instrumentation/opentelemetry-instrumentation-asgi/tests/test_asgi_middleware.py

@@ -14,6 +14,7 @@
 
 # pylint: disable=too-many-lines
 
+import asyncio
 import sys
 import unittest
 from timeit import default_timer
@@ -796,5 +797,38 @@ async def wrapped_app(scope, receive, send):
  )
 
 
+class TestAsgiApplicationRaisingError(AsgiTestBase):
+ def tearDown(self):
+ pass
+
+ @mock.patch(
+ "opentelemetry.instrumentation.asgi.collect_custom_request_headers_attributes",
+ side_effect=ValueError("whatever"),
+ )
+ def test_asgi_issue_1883(
+ self, mock_collect_custom_request_headers_attributes
+ ):
+ """
+ Test that exception UnboundLocalError local variable 'start' referenced before assignment is not raised
+ See https://github.com/open-telemetry/opentelemetry-python-contrib/issues/1883
+ """
+ app = otel_asgi.OpenTelemetryMiddleware(simple_asgi)
+ self.seed_app(app)
+ self.send_default_request()
+ try:
+ asyncio.get_event_loop().run_until_complete(
+ self.communicator.stop()
+ )
+ except ValueError as exc_info:
+ self.assertEqual(exc_info.args[0], "whatever")
+ except Exception as exc_info: # pylint: disable=W0703
+ self.fail(
+ "expecting ValueError('whatever'), received instead: "
+ + str(exc_info)
+ )
+ else:
+ self.fail("expecting ValueError('whatever')")
+
+
 if __name__ == "__main__":
  unittest.main()