httpx: instrument transport instead of client

Author: Kludex

instrumentation/opentelemetry-instrumentation-httpx/tests/test_httpx_integration.py

@@ -14,6 +14,8 @@
 
 # pylint: disable=too-many-lines
 
+from __future__ import annotations
+
 import abc
 import asyncio
 import typing
@@ -593,10 +595,10 @@ def create_transport(
         @abc.abstractmethod
         def create_client(
             self,
-            transport: typing.Union[
-                SyncOpenTelemetryTransport, AsyncOpenTelemetryTransport, None
-            ] = None,
-            **kwargs,
+            transport: SyncOpenTelemetryTransport
+            | AsyncOpenTelemetryTransport
+            | None = None,
+            **kwargs: typing.Any,
         ):
             pass
 
@@ -730,9 +732,9 @@ class BaseInstrumentorTest(BaseTest, metaclass=abc.ABCMeta):
         @abc.abstractmethod
         def create_client(
             self,
-            transport: typing.Union[
-                SyncOpenTelemetryTransport, AsyncOpenTelemetryTransport, None
-            ] = None,
+            transport: SyncOpenTelemetryTransport
+            | AsyncOpenTelemetryTransport
+            | None = None,
             **kwargs,
         ):
             pass
@@ -926,6 +928,17 @@ def test_instrument_client_called_on_the_class(self):
             self.assertEqual(result.text, "Hello!")
             self.assert_span(num_spans=1)
 
+        def test_instrument_multiple_clients_with_the_same_transport(self):
+            client1 = typing.cast(httpx.Client, self.create_client())
+            client2 = self.create_client(client1._transport)
+
+            HTTPXClientInstrumentor().instrument_client(client1)
+            HTTPXClientInstrumentor().instrument_client(client2)
+
+            result = self.perform_request(self.URL, client=client1)
+            self.assertEqual(result.text, "Hello!")
+            self.assert_span(num_spans=1)
+
         def test_instrumentation_without_client(self):
             HTTPXClientInstrumentor().instrument()
             results = [