fix: defer urllib3 and grpc eager loading in transport modules

Author: hebaalazzeh

packages/google-auth/google/auth/transport/grpc.py

@@ -36,7 +36,7 @@
 __lazy_modules__: Set[str] = {"grpc"}
 
 
-class AuthMetadataPlugin(grpc.AuthMetadataPlugin):
+class AuthMetadataPlugin(object):
     """A `gRPC AuthMetadataPlugin`_ that inserts the credentials into each
     request.
 
@@ -54,10 +54,6 @@ class AuthMetadataPlugin(grpc.AuthMetadataPlugin):
     """
 
     def __init__(self, credentials, request, default_host=None):
-        # pylint: disable=no-value-for-parameter
-        # pylint doesn't realize that the super method takes no arguments
-        # because this class is the same name as the superclass.
-        super(AuthMetadataPlugin, self).__init__()
         self._credentials = credentials
         self._request = request
         self._default_host = default_host

packages/google-auth/google/auth/transport/urllib3.py

@@ -66,10 +66,6 @@
     "packaging.version",
 }
 
-if version.parse(urllib3.__version__) >= version.parse("2.0.0"):  # pragma: NO COVER
-    RequestMethods = urllib3._request_methods.RequestMethods  # type: ignore
-else:  # pragma: NO COVER
-    RequestMethods = urllib3.request.RequestMethods  # type: ignore
 
 _LOGGER = logging.getLogger(__name__)
 
@@ -213,7 +209,7 @@ def _make_mutual_tls_http(cert, key):
     return http
 
 
-class AuthorizedHttp(RequestMethods):  # type: ignore
+class AuthorizedHttp(object):
     """A urllib3 HTTP class with credentials.
 
     This class is used to perform requests to API endpoints that require
@@ -296,6 +292,24 @@ def my_cert_callback():
             account credentials.
     """
 
+    _encode_url_methods = {"DELETE", "GET", "HEAD", "OPTIONS"}
+
+    def __getattr__(self, name):
+        if name in ("request", "request_encode_url", "request_encode_body"):
+            import types
+
+            if version.parse(urllib3.__version__) >= version.parse("2.0.0"):
+                rm = urllib3._request_methods.RequestMethods
+            else:
+                rm = urllib3.request.RequestMethods
+
+            method = getattr(rm, name)
+            return types.MethodType(method, self)
+
+        raise AttributeError(
+            f"'{self.__class__.__name__}' object has no attribute '{name}'"
+        )
+
     def __init__(
         self,
         credentials,