Making sure all endpoints define at least the minimum common responses

A common pitfall when using this package is the following: you define
an endpoint that can result in 400 Bad Request, but you forget to list 400
in the `responses` section of your endpoint in openapi.yaml. This package
then instead returns 500 Internal Server error, because it keeps the promise
that only defined responses will be allowed (unless you set
`enable_request_validation` to `False`, that is).

With this commit, all endpoints, by default need to have 200, 400 and 500
on the list of `responses` in openapi.yaml, otherwise the app won't start. Additionally, all
endpoints that accept a parameter, also need to have 404 on the list of
`responses`.

You can skip this check by setting `enable_endpoint_validation` to `False`.

Refs #22
Refs #49 (comment)
Refs #36

README.md

@@ -103,7 +103,7 @@ Some notes:
 Provided with `pyramid_openapi3` are a few validation features:
  * incoming request validation (i.e. what a client sends to your app)
  * outgoing response validation (i.e. what your app sends to a client)
- * endpoint validation (i.e. your app registers routes for all defined API endpoints)
+ * endpoint validation (i.e. all endpoints define minimal responses and have routes registered)
 
 These features are enabled as a default, but you can disable them if you need to:
 

pyramid_openapi3/__init__.py

@@ -42,7 +42,8 @@ def includeme(config: Configurator) -> None:
     config.add_directive("pyramid_openapi3_spec", add_spec_view)
     config.add_directive("pyramid_openapi3_spec_directory", add_spec_view_directory)
     config.add_tween("pyramid_openapi3.tween.response_tween_factory", over=EXCVIEW)
-    config.add_subscriber(check_all_routes, ApplicationCreated)
+    config.add_subscriber(validate_routes, ApplicationCreated)
+    config.add_subscriber(validate_minimal_responses, ApplicationCreated)
 
     if not config.registry.settings.get(  # pragma: no branch
         "pyramid_openapi3_extract_errors"
@@ -293,11 +294,11 @@ def openapi_validation_error(
     return exception_response(status_code, json_body=errors)
 
 
-def check_all_routes(event: ApplicationCreated):
-    """Assert all endpoints in the spec are registered as routes.
+def validate_routes(event: ApplicationCreated):
+    """Assert all endpoints in the spec have a route registered for them.
 
     Listen for ApplicationCreated event and assert all endpoints defined in
-    the API spec have been registered as Pyramid routes.
+    the API spec have been assigned a Pyramid route.
     """
 
     app = event.app
@@ -313,7 +314,7 @@ def check_all_routes(event: ApplicationCreated):
     if not app.registry.settings.get(
         "pyramid_openapi3.enable_endpoint_validation", True
     ):
-        logger.info("Endpoint validation against specification is disabled")
+        logger.info("Endpoint validation is disabled")
         return
 
     # Sometimes api routes are prefixed with `/api/v1` and similar, using
@@ -338,3 +339,28 @@ def remove_prefixes(path):
     missing = [r for r in paths if r not in routes]
     if missing:
         raise MissingEndpointsError(missing)
+
+
+def validate_minimal_responses(event: ApplicationCreated):
+    """Assert all endpoints in the spec have defined at least minimal responses.
+
+    By default this makes sure that all endpoints have the minimal required
+    responses defined in the spec: 200, 400 and 500
+
+    Additionally, all endpoints with parameters need to have 404 defined in the
+    spec.
+
+    Finally, it is possible to override the minimal required responses for
+    each endpoint by setting "pyramid_openapi3.endpoint_validation_overrides"
+    to {'/endpoint/path': {'post': [202, 400, 500]}}
+    """
+    app = event.app
+    minimal_responses = app.registry.settings.get(  # noqa
+        "pyramid_openapi3.endpoint_validation_minimal_responses", [200, 400, 500]
+    )
+    minimal_responses_with_parameters = app.registry.settings.get(  # noqa
+        "pyramid_openapi3.endpoint_validation_minimal_responses_with_parameters", [404]
+    )
+    overrides = app.registry.settings.get(  # noqa
+        "pyramid_openapi3.endpoint_validation_overrides", [404]
+    )

pyramid_openapi3/tests/test_app_construction.py

@@ -139,7 +139,7 @@ def test_disable_endpoint_validation(
 
     app_config.make_wsgi_app()
 
-    assert "Endpoint validation against specification is disabled" in caplog.text
+    assert "Endpoint validation is disabled" in caplog.text
 
 
 def test_unconfigured_app(