Simple input object intersection

src/index.ts

@@ -11,6 +11,7 @@ import unavailableOverrideTestCase from "./test-cases/unavailable-override";
 import overrideWithRequiresTestCase from "./test-cases/override-with-requires";
 import simpleInaccessible from "./test-cases/simple-inaccessible";
 import enumIntersection from "./test-cases/enum-intersection";
+import inputObjectIntersection from "./test-cases/input-object-intersection";
 
 const testCases = [
   unionIntersectionTestCase,
@@ -25,6 +26,7 @@ const testCases = [
   overrideWithRequiresTestCase,
   simpleInaccessible,
   enumIntersection,
+  inputObjectIntersection,
 ];
 
 function routerFetch(request: Request) {

src/supergraph.ts

@@ -38,7 +38,13 @@ export function serve(
   return {
     id,
     createRoutes(router: ReturnType<typeof createRouter>) {
+      let subgraphNames = new Set<string>();
       for (const subgraph of subgraphs) {
+        if (subgraphNames.has(subgraph.name)) {
+          throw new Error(`Duplicate subgraph name ${subgraph.name}`);
+        }
+
+        subgraphNames.add(subgraph.name);
         subgraph.createRoutes(id, router);
       }
 

src/test-cases/input-object-intersection/a.subgraph.ts

@@ -0,0 +1,47 @@
+import { createSubgraph } from "../../subgraph";
+import { users } from "./data";
+
+export default createSubgraph("a", {
+  typeDefs: /* GraphQL */ `
+    extend schema
+      @link(
+        url: "https://specs.apollo.dev/federation/v2.3"
+        import: ["@key", "@shareable"]
+      )
+
+    input UsersFilter {
+      first: Int!
+    }
+
+    type User @key(fields: "id") {
+      id: ID!
+      name: String! @shareable
+    }
+
+    type Query {
+      usersInA(filter: UsersFilter!): [User!]
+    }
+  `,
+  resolvers: {
+    Query: {
+      usersInA(_: {}, { filter }: { filter: { first: number } }) {
+        if ("offset" in filter) {
+          return [];
+        }
+
+        return users;
+      },
+    },
+    User: {
+      __resolveReference(key: { id: string }) {
+        const user = users.find((user) => user.id === key.id);
+
+        if (!user) {
+          return null;
+        }
+
+        return user;
+      },
+    },
+  },
+});

src/test-cases/input-object-intersection/b.subgraph.ts

@@ -0,0 +1,51 @@
+import { createSubgraph } from "../../subgraph";
+import { users } from "./data";
+
+export default createSubgraph("b", {
+  typeDefs: /* GraphQL */ `
+    extend schema
+      @link(
+        url: "https://specs.apollo.dev/federation/v2.3"
+        import: ["@key", "@shareable"]
+      )
+
+    input UsersFilter {
+      offset: Int
+      first: Int!
+    }
+
+    type User @key(fields: "id") {
+      id: ID!
+      name: String! @shareable
+    }
+
+    type Query {
+      usersInB(filter: UsersFilter!): [User!]
+    }
+  `,
+  resolvers: {
+    Query: {
+      usersInB(
+        _: {},
+        { filter }: { filter: { offset?: number; first: number } }
+      ) {
+        if (typeof filter.offset !== "undefined") {
+          return [];
+        }
+
+        return users;
+      },
+    },
+    User: {
+      __resolveReference(key: { id: string }) {
+        const user = users.find((user) => user.id === key.id);
+
+        if (!user) {
+          return null;
+        }
+
+        return user;
+      },
+    },
+  },
+});

src/test-cases/input-object-intersection/data.ts

@@ -0,0 +1,10 @@
+export const users = [
+  {
+    id: "u1",
+    name: "u1-name",
+  },
+  {
+    id: "u2",
+    name: "u2-name",
+  },
+];

src/test-cases/input-object-intersection/index.ts

@@ -0,0 +1,6 @@
+import { serve } from "../../supergraph";
+import a from "./a.subgraph";
+import b from "./b.subgraph";
+import test from "./test";
+
+export default serve("input-object-intersection", [a, b], test);

src/test-cases/input-object-intersection/test.ts

@@ -0,0 +1,49 @@
+import { createTest } from "../../test";
+
+export default [
+  createTest(
+    /* GraphQL */ `
+      query {
+        usersInA(filter: { first: 1 }) {
+          id
+        }
+      }
+    `,
+    {
+      data: {
+        usersInA: [
+          {
+            id: "u1",
+          },
+          {
+            id: "u2",
+          },
+        ],
+      },
+    }
+  ),
+  createTest(
+    /* GraphQL */ `
+      query {
+        usersInA(filter: { first: 1, offset: 2 }) {
+          id
+        }
+      }
+    `,
+    {
+      errors: true,
+    }
+  ),
+  createTest(
+    /* GraphQL */ `
+      query {
+        usersInB(filter: { first: 1, offset: 2 }) {
+          id
+        }
+      }
+    `,
+    {
+      errors: true,
+    }
+  ),
+];