Reduce interface expansion for types contained to a single service

packages/apollo-gateway/CHANGELOG.md

@@ -5,6 +5,7 @@
 > The changes noted within this `vNEXT` section have not been released yet.  New PRs and commits which introduce changes should include an entry in this `vNEXT` section as part of their development.  When a release is being prepared, a new header will be (manually) created below and the the appropriate changes within that release will be moved into the new section.
 
 * Fix onSchemaChange callbacks for unmanaged configs [#3605](https://github.com/apollographql/apollo-server/pull/3605)
+* Reduce interface expansion for types contained to a single service [#3582](https://github.com/apollographql/apollo-server/pull/3582)
 
 # v0.11.4
 

packages/apollo-gateway/src/__tests__/__fixtures__/schemas/product.ts

@@ -8,6 +8,7 @@ export const typeDefs = gql`
 
   extend type Query {
     product(upc: String!): Product
+    vehicle(id: String!): Vehicle
     topProducts(first: Int = 5): [Product]
     topCars(first: Int = 5): [Car]
   }
@@ -65,11 +66,32 @@ export const typeDefs = gql`
     details: ProductDetailsBook
   }
 
-  type Car @key(fields: "id") {
+  interface Vehicle {
     id: String!
+    description: String
     price: String
   }
 
+  type Car implements Vehicle @key(fields: "id") {
+    id: String!
+    description: String
+    price: String
+  }
+
+  type Van implements Vehicle @key(fields: "id") {
+    id: String!
+    description: String
+    price: String
+  }
+
+  union Thing = Car | Ikea
+
+  extend type User @key(fields: "id") {
+    id: ID! @external
+    vehicle: Vehicle
+    thing: Thing
+  }
+
   # Value type
   type KeyValue {
     key: String!
@@ -131,17 +153,25 @@ const products = [
   { __typename: 'Book', isbn: '0987654321', price: 29 },
 ];
 
-const cars = [
+const vehicles = [
   {
     __typename: 'Car',
     id: '1',
+    description: 'Humble Toyota',
     price: 9990,
   },
   {
     __typename: 'Car',
     id: '2',
+    description: 'Awesome Tesla',
     price: 12990,
   },
+  {
+    __typename: 'Van',
+    id: '3',
+    description: 'Just a van...',
+    price: 15990,
+  },
 ];
 
 export const resolvers: GraphQLResolverMap<any> = {
@@ -176,13 +206,34 @@ export const resolvers: GraphQLResolverMap<any> = {
   },
   Car: {
     __resolveReference(object) {
-      return cars.find(car => car.id === object.id);
+      return vehicles.find(vehicles => vehicles.id === object.id);
+    },
+  },
+  Van: {
+    __resolveReference(object) {
+      return vehicles.find(vehicles => vehicles.id === object.id);
+    },
+  },
+  Thing: {
+    __resolveType(object) {
+      return 'id' in object ? 'Car' : 'Ikea';
+    },
+  },
+  User: {
+    vehicle(user) {
+      return vehicles.find(vehicles => vehicles.id === user.id);
+    },
+    thing(user) {
+      return vehicles.find(vehicles => vehicles.id === user.id);
     },
   },
   Query: {
     product(_, args) {
       return products.find(product => product.upc === args.upc);
     },
+    vehicle(_, args) {
+      return vehicles.find(vehicles => vehicles.id === args.id);
+    },
     topProducts(_, args) {
       return products.slice(0, args.first);
     },

packages/apollo-gateway/src/__tests__/__fixtures__/schemas/reviews.ts

@@ -52,7 +52,17 @@ export const typeDefs = gql`
     relatedReviews: [Review!]! @requires(fields: "similarBooks { isbn }")
   }
 
-  extend type Car @key(fields: "id") {
+  extend interface Vehicle {
+    retailPrice: String
+  }
+
+  extend type Car implements Vehicle @key(fields: "id") {
+    id: String! @external
+    price: String @external
+    retailPrice: String @requires(fields: "price")
+  }
+
+  extend type Van implements Vehicle @key(fields: "id") {
     id: String! @external
     price: String @external
     retailPrice: String @requires(fields: "price")
@@ -217,6 +227,11 @@ export const resolvers: GraphQLResolverMap<any> = {
       return car.price;
     },
   },
+  Van: {
+    retailPrice(van) {
+      return van.price;
+    },
+  },
   MetadataOrError: {
     __resolveType(object) {
       return 'key' in object ? 'KeyValue' : 'Error';

packages/apollo-gateway/src/__tests__/executeQueryPlan.test.ts

@@ -15,6 +15,10 @@ import { buildQueryPlan, buildOperationContext } from '../buildQueryPlan';
 import { executeQueryPlan } from '../executeQueryPlan';
 import { LocalGraphQLDataSource } from '../datasources/LocalGraphQLDataSource';
 
+import { astSerializer, queryPlanSerializer } from '../snapshotSerializers';
+expect.addSnapshotSerializer(astSerializer);
+expect.addSnapshotSerializer(queryPlanSerializer);
+
 function buildLocalService(modules: GraphQLSchemaModule[]) {
   const schema = buildFederatedSchema(modules);
   return new LocalGraphQLDataSource(schema);
@@ -434,6 +438,119 @@ describe('executeQueryPlan', () => {
     expect(response.errors).toBeUndefined();
   });
 
+  it(`can execute queries on interface types`, async () => {
+    const query = gql`
+      query {
+        vehicle(id: "1") {
+          description
+          price
+          retailPrice
+        }
+      }
+    `;
+
+    const operationContext = buildOperationContext(schema, query);
+    const queryPlan = buildQueryPlan(operationContext);
+
+    const response = await executeQueryPlan(
+      queryPlan,
+      serviceMap,
+      buildRequestContext(),
+      operationContext,
+    );
+
+    expect(response.data).toMatchInlineSnapshot(`
+      Object {
+        "vehicle": Object {
+          "description": "Humble Toyota",
+          "price": "9990",
+          "retailPrice": "9990",
+        },
+      }
+    `);
+  });
+
+  it(`can execute queries whose fields are interface types`, async () => {
+    const query = gql`
+      query {
+        user(id: "1") {
+          name
+          vehicle {
+            description
+            price
+            retailPrice
+          }
+        }
+      }
+    `;
+
+    const operationContext = buildOperationContext(schema, query);
+    const queryPlan = buildQueryPlan(operationContext);
+
+    const response = await executeQueryPlan(
+      queryPlan,
+      serviceMap,
+      buildRequestContext(),
+      operationContext,
+    );
+
+    expect(response.data).toMatchInlineSnapshot(`
+      Object {
+        "user": Object {
+          "name": "Ada Lovelace",
+          "vehicle": Object {
+            "description": "Humble Toyota",
+            "price": "9990",
+            "retailPrice": "9990",
+          },
+        },
+      }
+    `);
+  });
+
+  it(`can execute queries whose fields are union types`, async () => {
+    const query = gql`
+      query {
+        user(id: "1") {
+          name
+          thing {
+            ... on Vehicle {
+              description
+              price
+              retailPrice
+            }
+            ... on Ikea {
+              asile
+            }
+          }
+        }
+      }
+    `;
+
+    const operationContext = buildOperationContext(schema, query);
+    const queryPlan = buildQueryPlan(operationContext);
+
+    const response = await executeQueryPlan(
+      queryPlan,
+      serviceMap,
+      buildRequestContext(),
+      operationContext,
+    );
+
+    expect(response.data).toMatchInlineSnapshot(`
+      Object {
+        "user": Object {
+          "name": "Ada Lovelace",
+          "thing": Object {
+            "description": "Humble Toyota",
+            "price": "9990",
+            "retailPrice": "9990",
+          },
+        },
+      }
+    `);
+  });
+
   it('can execute queries with falsey @requires (except undefined)', async () => {
     const query = gql`
       query {