extend type is not working in importSchema

app.js

# const { importSchema } = require("graphql-import");
#  importSchema("app/graphql/schema.graphql")

# Fixed
const {
  ApolloServer,
  gql
} = require("apollo-server-express");
const fs = require("fs");
const typeDefs = gql`
  ${fs.readFileSync(__dirname.concat("/schema.graphql"), "utf8")}
`;