Apollo GraphQL Test Example with Jest

Movie-test.js

import fs from 'fs'
import { makeExecutableSchema } from 'graphql-tools'
import { graphql } from 'graphql'
// the actual resolvers
import resolvers from '../src/resolvers'
// the mock service
import mockMovieService from './mocks/mockMovieService'

// a nice structure for test cases
// found at https://hackernoon.com/extensive-graphql-testing-57e8760f1c25
const allMoviesTestCase = {
    id: 'All Movies and Related Directors Test Case',
    query: `
      query {
        allMovies {
           id 
           title
           year
           director{
                firstName
                lastName
           }
        }
      }
    `,
    variables: { },

    // injecting the mock movie service with canned responses
    context: { movieService: mockMovieService },

    // expected result 
    expected: { data: { allMovies: [
        {id: '1', title: 'Interstellar', year: '2014', director: { firstName: 'Christopher', lastName: 'Nolan' }},
        {id: '2', title: 'Mad Max: Fury Road', year: '2015', director: { firstName: 'George', lastName: 'Miller' }}] } }
}

describe('My Test Cases', () => {
    // array of all test cases, just 1 for now
    const cases = [allMoviesTestCase]
    // reading the actual schema
    const typeDefs = fs.readFileSync('./src/schemas/Movie.graphql', 'utf8')
    // make the actual schema and resolvers executable
    const schema = makeExecutableSchema({ typeDefs, resolvers })
    
    // running the test for each case in the cases array
    cases.forEach(obj => {
        const { id, query, variables, context, expected } = obj

        test(`query: ${id}`, async () => {
            const result = await graphql(schema, query, null, context, variables)
            return expect(result).toEqual(expected)
        })
    })
})

@nzaghini Thank you for this. Can you show me your './mocks/mockMovieService' file?

hey! here we go!

// ********* DUMMY DATA SOURCE *********  //

const directors = [
    {id: 1, firstName: 'Christopher', lastName: 'Nolan', movies: [1, 3]},
    {id: 2, firstName: 'George', lastName: 'Miller', movies: [2]}]
const movies = [
    {id: 1, title: 'Interstellar', year: 2014, directorId: 1},
    {id: 2, title: 'Mad Max: Fury Road', year: 2015, directorId: 2}]

const allDirectors = () => directors
const allMovies = () => movies

module.exports = { allDirectors, allMovies }

Thank you!

My last issue is that my resolvers expect data sources but there are none provided so the resolvers are failing to load as a result. Would you be also willing to share src/resolvers ? Apologies :)

Never mind, I believe I've sorted things out. dropping it here in case it helps anyone:

const { mockServer } = require('graphql-tools');
const { describe, it } = require('mocha');
const { expect } = require('chai');
const { makeExecutableSchema } = require('graphql-tools');
const { typeDefs } = require('./typeDefs');

const schema = makeExecutableSchema({ `
    type Query {
        """
            This returns an array of Tags from the database
        """
        tags: [Tag]
    }
    type Tag {
        id: Int!
        tag: String!
    }
`});

const tagString = 'Hello';

const mocks = {
    Tag: () => ({
        tag: tagString,
    }),
};

const server = mockServer(schema, mocks);

const query = `
query {
    tags {
        id
        tag
    }
}
`;
const variables = {};

server.query(query, variables).then((response) => {
    describe('Tags', () => {
        it('query should return data', () => {
            expect(response.data.tags).to.have.lengthOf(2);
        });
        it('tag name should match the mocked data', () => {
            expect(response.data.tags[0].tag).to.equal(tagString);
        });
    });
});