test: add test for injecting custom buildservice into gateway

lib/interfaces/gql-gateway-module-options.interface.ts

@@ -22,7 +22,7 @@ export interface GatewayOptionsFactory {
 export interface GatewayModuleAsyncOptions extends Pick<ModuleMetadata, 'imports'> {
   useExisting?: Type<GatewayOptionsFactory>;
   useClass?: Type<GatewayOptionsFactory>;
-  useFactory?: (...args: any[]) => Promise<GqlModuleOptions> | GqlModuleOptions;
+  useFactory?: (...args: any[]) => Promise<GatewayModuleOptions> | GatewayModuleOptions;
   inject?: any[];
 }
 

tests/e2e/graphql-gateway-buildservice.spec.ts

@@ -0,0 +1,87 @@
+import { INestApplication } from '@nestjs/common';
+import { Test } from '@nestjs/testing';
+import * as request from 'supertest';
+import { AppModule as PostsModule } from '../graphql-federation/posts-service/federation-posts.module';
+import { AppModule as UsersModule } from '../graphql-federation/users-service/federation-users.module';
+import { AppModule as GatewayModule } from '../graphql-federation/gateway/gateway-buildservice.module';
+import { RemoteGraphQLDataSource } from '@apollo/gateway';
+import { GRAPHQL_GATEWAY_BUILD_SERVICE } from '../../lib/graphql.constants';
+
+describe('GraphQL Gateway buildservice', () => {
+  let postsApp: INestApplication;
+  let usersApp: INestApplication;
+  let gatewayApp: INestApplication;
+  let buildServiceHook: Function;
+
+  beforeEach(async () => {
+    buildServiceHook = jest.fn();
+    const usersModule = await Test.createTestingModule({
+      imports: [UsersModule],
+    }).compile();
+
+    usersApp = usersModule.createNestApplication();
+    await usersApp.listenAsync(3001);
+
+    const postsModule = await Test.createTestingModule({
+      imports: [PostsModule],
+    }).compile();
+
+    postsApp = postsModule.createNestApplication();
+    await postsApp.listenAsync(3002);
+
+    const gatewayModule = await Test.createTestingModule({
+      imports: [GatewayModule],
+    })
+      .overrideProvider(GRAPHQL_GATEWAY_BUILD_SERVICE)
+      .useValue(({ url }) => {
+        return new RemoteGraphQLDataSource({ url, willSendRequest: buildServiceHook as any });
+      })
+      .compile();
+
+    gatewayApp = gatewayModule.createNestApplication();
+    await gatewayApp.init();
+  });
+
+  it(`should run query through build service`, async () => {
+    await request(gatewayApp.getHttpServer())
+      .post('/graphql')
+      .send({
+        operationName: null,
+        variables: {},
+        query: `
+        {
+          getPosts {
+            id,
+            title,
+            body,
+            user {
+              id,
+              name,
+            }
+          }
+        }`,
+      })
+      .expect(200, {
+        data: {
+          getPosts: [
+            {
+              id: '1',
+              title: 'Hello world',
+              body: 'Lorem ipsum dolor sit amet, consectetur adipiscing elit.',
+              user: {
+                id: '5',
+                name: 'GraphQL',
+              },
+            },
+          ],
+        },
+      });
+    expect(buildServiceHook).toHaveBeenCalled();
+  });
+
+  afterEach(async () => {
+    await postsApp.close();
+    await usersApp.close();
+    await gatewayApp.close();
+  });
+});

tests/graphql-federation/gateway/gateway-buildservice.module.ts

@@ -0,0 +1,34 @@
+import { Module } from '@nestjs/common';
+import { GraphQLGatewayModule } from '../../../lib/graphql-gateway.module';
+import { GRAPHQL_GATEWAY_BUILD_SERVICE } from '../../../lib/graphql.constants';
+import { RemoteGraphQLDataSource } from '@apollo/gateway';
+
+@Module({
+  providers: [
+    {
+      provide: GRAPHQL_GATEWAY_BUILD_SERVICE,
+      useValue: ({ name, url }) => {
+        console.log('BuildService: %s', name);
+        return new RemoteGraphQLDataSource({ url });
+      },
+    },
+  ],
+  exports: [GRAPHQL_GATEWAY_BUILD_SERVICE],
+})
+class BuildServiceModule {}
+
+@Module({
+  imports: [
+    GraphQLGatewayModule.forRootAsync({
+      useFactory: async () => ({
+        serviceList: [
+          { name: 'users', url: 'http://localhost:3001/graphql' },
+          { name: 'posts', url: 'http://localhost:3002/graphql' },
+        ],
+      }),
+      imports: [BuildServiceModule],
+      inject: [GRAPHQL_GATEWAY_BUILD_SERVICE],
+    }),
+  ],
+})
+export class AppModule {}