fixing mongoose disconnect using Jest

before.js

describe('User.formSubmit() Mutation', () => {
  beforeAll(async (done) => {
    await mongoose.connect(`${MONGO_URI}${MONGO_DB}`, { useNewUrlParser: true });
    done();
  });

  afterAll(async (done) => {
    await mongoose.disconnect();
    done();
  });

  test('suite setup ready', () => {
    // removed for brevity
  });
});