Fix reference parameter/response with MarshmallowPlugin

src/apispec/ext/marshmallow/__init__.py

@@ -83,7 +83,9 @@ def init_spec(self, spec):
     def resolve_parameters(self, parameters):
         resolved = []
         for parameter in parameters:
-            if not isinstance(parameter.get("schema", {}), dict):
+            if isinstance(parameter, dict) and not isinstance(
+                parameter.get("schema", {}), dict
+            ):
                 schema_instance = resolve_schema_instance(parameter["schema"])
                 if "in" in parameter:
                     del parameter["schema"]
@@ -109,8 +111,12 @@ def resolve_schema(self, data):
         corresponding dict to convert Marshmallow Schema object or class into dict
 
         :param APISpec spec: `APISpec` containing refs.
-        :param dict data: the parameter or response dictionary that may contain a schema
+        :param dict|str data: either a parameter or response dictionary that may
+            contain a schema, or a reference provided as string
         """
+        if not isinstance(data, dict):
+            return
+
         # OAS 2 component or OAS 3 header
         if "schema" in data:
             data["schema"] = self.openapi.resolve_schema_dict(data["schema"])

tests/test_ext_marshmallow.py

@@ -571,7 +571,7 @@ def test_schema_array_uses_ref_if_available_v2(self, spec_fixture):
             },
         )
         get = get_paths(spec_fixture.spec)["/pet"]["get"]
-        len(get["parameters"]) == 1
+        assert len(get["parameters"]) == 1
         resolved_schema = {
             "type": "array",
             "items": {"$ref": ref_path(spec_fixture.spec) + "Pet"},
@@ -608,16 +608,15 @@ def test_schema_array_uses_ref_if_available_v3(self, spec_fixture):
                 }
             },
         )
-        p = get_paths(spec_fixture.spec)["/pet"]
-        assert "get" in p
-        op = p["get"]
+        get = get_paths(spec_fixture.spec)["/pet"]["get"]
+        assert len(get["parameters"]) == 1
         resolved_schema = {
             "type": "array",
             "items": {"$ref": ref_path(spec_fixture.spec) + "Pet"},
         }
-        request_schema = op["parameters"][0]["content"]["application/json"]["schema"]
+        request_schema = get["parameters"][0]["content"]["application/json"]["schema"]
         assert request_schema == resolved_schema
-        response_schema = op["responses"][200]["content"]["application/json"]["schema"]
+        response_schema = get["responses"][200]["content"]["application/json"]["schema"]
         assert response_schema == resolved_schema
 
     @pytest.mark.parametrize("spec_fixture", ("2.0",), indirect=True)
@@ -684,6 +683,34 @@ def test_schema_partially_v3(self, spec_fixture):
             },
         }
 
+    def test_parameter_reference(self, spec_fixture):
+        if spec_fixture.spec.openapi_version.major < 3:
+            param = {"schema": PetSchema}
+            reference = "#/parameters/Pet"
+        else:
+            param = {"content": {"application/json": {"schema": PetSchema}}}
+            reference = "#/components/parameters/Pet"
+        spec_fixture.spec.components.parameter("Pet", "body", param)
+        spec_fixture.spec.path(
+            path="/parents", operations={"get": {"parameters": ["Pet"]}}
+        )
+        get = get_paths(spec_fixture.spec)["/parents"]["get"]
+        assert get["parameters"] == [{"$ref": reference}]
+
+    def test_response_reference(self, spec_fixture):
+        if spec_fixture.spec.openapi_version.major < 3:
+            resp = {"schema": PetSchema}
+            reference = "#/responses/Pet"
+        else:
+            resp = {"content": {"application/json": {"schema": PetSchema}}}
+            reference = "#/components/responses/Pet"
+        spec_fixture.spec.components.response("Pet", resp)
+        spec_fixture.spec.path(
+            path="/parents", operations={"get": {"responses": {"200": "Pet"}}}
+        )
+        get = get_paths(spec_fixture.spec)["/parents"]["get"]
+        assert get["responses"] == {"200": {"$ref": reference}}
+
     def test_schema_global_state_untouched_2json(self, spec_fixture):
         assert RunSchema._declared_fields["sample"]._Nested__schema is None
         data = spec_fixture.openapi.schema2jsonschema(RunSchema)