Failing test: stitching fails when all selections on a field are delegated

packages/stitch/tests/__snapshots__/blah.test.ts.snap

@@ -0,0 +1,13 @@
+// Jest Snapshot v1, https://goo.gl/fbAQLP
+
+exports[`Blah creates expected schema 1`] = `
+"type Query {
+  thingA(id: ID!): String
+  namespaceInB: NamespaceInB
+}
+
+type NamespaceInB {
+  dummy: ID!
+  thingA(id: ID!): String
+}"
+`;

packages/stitch/tests/blah.test.ts

@@ -0,0 +1,116 @@
+import { graphql, OperationTypeNode, printSchema } from 'graphql/index';
+import { delegateToSchema } from '@graphql-tools/delegate';
+import { makeExecutableSchema } from '@graphql-tools/schema';
+import { stitchSchemas } from '@graphql-tools/stitch';
+
+describe('Blah', () => {
+  const aResolvers = {
+    Query: {
+      thingA: async (_source: any, args: { id: string }) => {
+        return args.id;
+      },
+    },
+  };
+
+  const bResolvers = {
+    Query: {
+      namespaceInB: () => true,
+    },
+  };
+
+  const aggSchema = makeExecutableSchema({
+    typeDefs: /* GraphQL */ `
+      type Query {
+        thingA(id: ID!): String
+      }
+    `,
+    resolvers: aResolvers,
+  });
+
+  const bbfSchema = makeExecutableSchema({
+    typeDefs: /* GraphQL */ `
+      type Query {
+        namespaceInB: NamespaceInB
+      }
+
+      type NamespaceInB {
+        dummy: ID!
+      }
+    `,
+    resolvers: bResolvers,
+  });
+
+  const stitchedSchema = stitchSchemas({
+    subschemas: [{ schema: aggSchema }, { schema: bbfSchema }],
+    typeDefs: /* GraphQL */ `
+      extend type NamespaceInB {
+        thingA(id: ID!): String
+      }
+    `,
+    resolvers: {
+      NamespaceInB: {
+        thingA: {
+          resolve: async (_parent, args, context, info) => {
+            const result = await delegateToSchema({
+              schema: aggSchema,
+              operation: OperationTypeNode.QUERY,
+              fieldName: 'thingA',
+              args,
+              context,
+              info,
+            });
+            return result;
+          },
+        },
+      },
+    },
+  });
+
+  it('creates expected schema', () => {
+    expect(printSchema(stitchedSchema)).toMatchSnapshot();
+  });
+
+  it('executes stitched query with dummy field', async () => {
+    const query = /* GraphQL */ `
+      query {
+        namespaceInB {
+          __typename
+          thingA(id: "abc")
+        }
+      }
+    `;
+
+    const result = await graphql({
+      schema: stitchedSchema,
+      source: query,
+    });
+    expect(result.errors).toBe(undefined);
+    expect(result.data).toEqual({
+      namespaceInB: {
+        __typename: 'NamespaceInB',
+        thingA: 'abc',
+      },
+    });
+  });
+
+  it('executes stitched query without dummy field', async () => {
+    const query = /* GraphQL */ `
+      query {
+        namespaceInB {
+          thingA(id: "abc")
+        }
+      }
+    `;
+
+    const result = await graphql({
+      schema: stitchedSchema,
+      source: query,
+    });
+    expect(result.errors).toBe(undefined);
+    expect(result.data).toEqual({
+      namespaceInB: {
+        thingA: 'abc',
+      },
+    });
+  });
+});