Fix validation error in for custom auth classes

dlt/common/typing.py

@@ -484,3 +484,18 @@ def decorator(
         return func
 
     return decorator
+
+
+def add_value_to_literal(literal: Any, value: Any) -> None:
+    """Extends a Literal at runtime with a new value.
+
+    Args:
+        literal (Type[Any]): Literal to extend
+        value (Any): Value to add
+
+    """
+    type_args = get_args(literal)
+
+    if value not in type_args:
+        type_args += (value,)
+        literal.__args__ = type_args

dlt/sources/rest_api/config_setup.py

@@ -20,6 +20,7 @@
 from dlt.common.configuration import resolve_configuration
 from dlt.common.schema.utils import merge_columns
 from dlt.common.utils import update_dict_nested, exclude_keys
+from dlt.common.typing import add_value_to_literal
 from dlt.common import jsonpath
 
 from dlt.extract.incremental import Incremental
@@ -64,6 +65,7 @@
     ResponseActionDict,
     Endpoint,
     EndpointResource,
+    AuthType,
 )
 
 
@@ -153,6 +155,8 @@ def register_auth(
         )
     AUTH_MAP[auth_name] = auth_class
 
+    add_value_to_literal(AuthType, auth_name)
+
 
 def get_auth_class(auth_type: str) -> Type[AuthConfigBase]:
     try:
@@ -285,7 +289,7 @@ def build_resource_dependency_graph(
             resolved_param_map[resource_name] = None
             break
         assert isinstance(endpoint_resource["endpoint"], dict)
-        # connect transformers to resources via resolved params
+        # find resolved parameters to connect dependent resources
         resolved_params = _find_resolved_params(endpoint_resource["endpoint"])
 
         # set of resources in resolved params

tests/sources/rest_api/configurations/test_custom_auth_config.py

@@ -5,7 +5,7 @@
 
 from dlt.sources import rest_api
 from dlt.sources.helpers.rest_client.auth import APIKeyAuth, OAuth2ClientCredentials
-from dlt.sources.rest_api.typing import ApiKeyAuthConfig, AuthConfig
+from dlt.sources.rest_api.typing import ApiKeyAuthConfig, AuthConfig, RESTAPIConfig
 
 
 class CustomOAuth2(OAuth2ClientCredentials):
@@ -77,3 +77,18 @@ class NotAuthConfigBase:
                 "not_an_auth_config_base", NotAuthConfigBase  # type: ignore
             )
         assert e.match("Invalid auth: NotAuthConfigBase.")
+
+    def test_validate_config_raises_no_error(self, custom_auth_config: AuthConfig) -> None:
+        rest_api.config_setup.register_auth("custom_oauth_2", CustomOAuth2)
+
+        valid_config: RESTAPIConfig = {
+            "client": {
+                "base_url": "https://example.com",
+                "auth": custom_auth_config,
+            },
+            "resources": ["test"],
+        }
+
+        rest_api.rest_api_source(valid_config)
+
+        del rest_api.config_setup.AUTH_MAP["custom_oauth_2"]