Merge pull request #246 from apollo-server-integrations/trevor/defer-support

Implement `@defer` support

Author: olyop

.circleci/config.yml

@@ -43,6 +43,18 @@ jobs:
       - run: npm run test:ci
       - store_test_results:
           path: junit.xml
+  Incremental Delivery:
+    docker:
+      - image: cimg/base:stable
+    environment:
+      INCREMENTAL_DELIVERY_TESTS_ENABLED: t
+    steps:
+      - setup-node:
+          node-version: "18"
+      # Install a prerelease of graphql-js 17 with incremental delivery support.
+      # --legacy-peer-deps because nothing expects v17 yet.
+      - run: npm i --legacy-peer-deps graphql@17.0.0-alpha.1.canary.pr.3361.04ab27334641e170ce0e05bc927b972991953882
+      - run: npm run test:ci
   Lint:
     docker:
       - image: cimg/base:stable
@@ -69,3 +81,4 @@ workflows:
                 - "16"
                 - "18"
                 - "20"
+      - Incremental Delivery

src/handler.ts

@@ -1,3 +1,5 @@
+import { Readable } from "node:stream";
+
 import { ApolloServer, BaseContext } from "@apollo/server";
 import type { WithRequired } from "@apollo/utils.withrequired";
 import type {
@@ -114,8 +116,10 @@ export function fastifyApolloHandler<
 
 		if (body.kind === "complete") {
 			return body.string;
-		} else {
-			throw new Error("Incremental delivery not implemented yet.");
 		}
+
+		const readable = Readable.from(body.asyncIterator);
+		// @ts-ignore something wrong with the `ReplyType` but not sure what
+		return reply.send(readable);
 	};
 }

tests/handler.test.ts

@@ -34,7 +34,4 @@ defineIntegrationTestSuite(
 			url,
 		};
 	},
-	{
-		noIncrementalDelivery: true,
-	},
 );

tests/plugin.test.ts

@@ -34,7 +34,4 @@ defineIntegrationTestSuite(
 			url,
 		};
 	},
-	{
-		noIncrementalDelivery: true,
-	},
 );