Is it possible to mock GraphQL services at the gateway level?

Help
1

I would like to mock my graphql subgraph at the gateway level.
Right now each subgraph mock its own service independently.
e.g of one subgraph :

const {buildSubgraphSchema} = require(‘@apollo/subgraph’);
const { addMocksToSchema } = require(‘@graphql-tools/mock’);
  
const server = new ApolloServer({
   schema: addMocksToSchema({
      schema: buildSubgraphSchema({ typeDefs, resolvers }),
   }),
});
try {
   const { url } = await startStandaloneServer(server);
   console.log(🚀 Subgraph ${subgraphName} running at ${url});
} catch (err) {
   console.error(err);
}

But to have a consistent data result across the supergraphql schema, i would need to have a similar above setup at the gateway level.

Is there any apolloGateway parameter that could mock my service such as :

const supergraphSdl = readFileSync(‘./src/supergraph.graphql’).toString()
const gateway = new ApolloGateway({
   supergraphSdl,
   mocks:true
});
const server = new ApolloServer({
   gateway,
});
const { url } = await startStandaloneServer(server);
console.log(🚀 Server ready at ${url});

Thank you in advance for your help

2

I have found a way of doing it
Below the code of my gateway index.js :

import { ApolloServer } from ‘@apollo/server’;
import { startStandaloneServer } from ‘@apollo/server/standalone’;
import { ApolloGateway } from ‘@apollo/gateway’;
import { readFileSync } from ‘fs’;
import { addMocksToSchema } from ‘@graphql-tools/mock’;
import { mocks } from “./mocks.js”;
 
const supergraphSdl = readFileSync(‘./src/supergraph.graphql’).toString()
const gateway = new ApolloGateway({
  supergraphSdl,
});
const {schema, executor} = await gateway.load();
const server = new ApolloServer({
  schema: addMocksToSchema({
    schema: schema,
    mocks : mocks,
  }),
  executor,
});
const { url } = await startStandaloneServer(server);
console.log(🚀 Server ready at ${url});

mocks.js :

import { faker } from “@faker-js/faker”;
 
export const mocks = {
   Int: () => faker.datatype.number(100),
   Float: () => faker.datatype.float({ min: 10, max: 100, precision: 0.001 }),
   String: () => faker.random.words(),
   Boolean: () => faker.datatype.boolean(),
};

If you want to use the default graphql mocking just replace the line

delete line 6 : import { mocks } from “./mocks.js”;
replace line 16 : mocks : mocks by mocks : true

3

I give additional information just in case you want to use mocks with gateway federation and express
Here is my code

import { ApolloServer } from ‘@apollo/server’;
import { ApolloGateway } from ‘@apollo/gateway’;
import { readFileSync } from ‘fs’;
import { addMocksToSchema } from ‘@graphql-tools/mock’;
import bodyParser from ‘body-parser’;
const { json } = bodyParser;
import { mocks } from “./mocks.js”;
import { expressMiddleware } from ‘@apollo/server/express4’;
import express from ‘express’;
import http from ‘http’;
import cookieParser from ‘cookie-parser’

const supergraphSdl = readFileSync(‘./src/supergraph.graphql’).toString()

const gateway = new ApolloGateway({
  supergraphSdl,
  debug:true,
});
const {schema, executor} = await gateway.load();

const app = express();
const httpServer = http.createServer(app);

const server = new ApolloServer({
  schema: addMocksToSchema({
    schema: schema,
    mocks : mocks,
  }),
  executor,
});
await server.start();

app.use(
  ‘/’,
  cookieParser(),
  json(),
  expressMiddleware(server)
);

app.set(‘trust proxy’,true);

let port = 4000
await new Promise((resolve) => httpServer.listen({ port: port }, resolve));

console.log(🚀 Server ready at http://localhost:${port}/);

I hope i can help