fix: setup middleware without client argument for starlette (elastic#1952)

Author: gabriel-f-santos

.ci/.matrix_exclude.yml

@@ -279,3 +279,5 @@ exclude:
  FRAMEWORK: pyodbc-newest # error on wheel
  - VERSION: python-3.12
  FRAMEWORK: cassandra-newest # c extension issue
+ - VERSION: python-3.12
+ FRAMEWORK: starlette-newest # waiting for 3.12.2 for this fix: https://github.com/python/cpython/pull/111221

elasticapm/contrib/starlette/__init__.py

@@ -105,7 +105,7 @@ class ElasticAPM:
  >>> elasticapm.capture_message('hello, world!')
  """
 
- def __init__(self, app: ASGIApp, client: Optional[Client], **kwargs) -> None:
+ def __init__(self, app: ASGIApp, client: Optional[Client] = None, **kwargs) -> None:
  """
 
  Args:

tests/contrib/asyncio/starlette_tests.py

@@ -534,3 +534,11 @@ def test_transaction_active_in_base_exception_handler(app, elasticapm_client):
  assert exc.transaction_id
 
  assert len(elasticapm_client.events[constants.TRANSACTION]) == 1
+
+
+def test_middleware_without_client_arg():
+ with mock.patch.dict("os.environ", {"ELASTIC_APM_SERVICE_NAME": "foo"}):
+ app = Starlette()
+ elasticapm = ElasticAPM(app)
+
+ assert elasticapm.client.config.service_name == "foo"