An example of how to test graphql subscriptions with jest

UserAddedSubscription.spec.ts

import { graphql, subscribe, parse } from 'graphql';

import {
  connectMongoose,
  disconnectMongoose,
  clearDbAndRestartCounters,
  getContext,
} from '../../../../../test/helpers';
import { schema } from '../../../../schema/schema';

beforeAll(connectMongoose);
beforeEach(clearDbAndRestartCounters);
afterAll(disconnectMongoose);

describe('UserAdded Subscription', () => {
  it('should complete a user subscription after UserAddMutation', async () => {
    const mutation = `
      mutation M($input: UserAddInput!) {
        UserAdd(input: $input) {
          token
          error
        }
      }
    `;

    const subscription = `
      subscription S($input: UserAddedInput!) {
        UserAdded(input: $input) {
          user {
            name
            username
            email
            isActive
            followers {
              totalCount
            }
            following {
              totalCount
            }
          }
        }
      }
    `;

    const rootValue = {};
    const contextValue = await getContext({});
    const variablesMutation = {
      input: {
        name: 'Awesome Name',
        username: 'awesomeusername',
        email: 'awesome@email.com',
        password: '12345',
      },
    };
    const variablesSubscription = {
      input: {},
    };

    const triggerSubscription = graphql(schema, mutation, rootValue, contextValue, variablesMutation);
    const result = await subscribe(schema, parse(subscription), triggerSubscription, contextValue, variablesSubscription);

    expect((await result.next()).value.data).toEqual({
      UserAdded: {
        user: {
          name: 'Awesome Name',
          username: 'awesomeusername',
          email: null,
          isActive: true,
          followers: {
            totalCount: 0,
          },
          following: {
            totalCount: 0,
          },
        },
      },
    });
  });
});