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# ServiceMock

ServiceMock is a simple JavaScript object:

const myServiceMock = {
  graphql: {
    typeDefs: `
      type Query {
        books: [Book]
      }
      type Book {
        id: Int
        title: String
      }
    `
  }
}

# graphql

The only required keys are either graphql.typeDefs or graphql.typeDefsPath.

# typeDefs or typeDefsPath

One of these two keys is required:

# typeDefs

string

A string containing a GraphQL Schema definition in GSL.

# typeDefsPath

string | URL

A string or URL pointing to a file containing a GraphQL Schema definition in GSL.

# mocks

Record<string, Record<string, () => any>>

The mocks object can provide a function for each type field. The object's keys must be Typenames, and values are objects with field names as keys.

Example (assuming the types Book and User exist in the schema):

const mocks = {
  Book: {
    title: () => faker.random.words(4)
  },
  User: {
    email: () => faker.internet.email(),
    username: () => faker.internet.userName()
  }
}

# resolvers

(Store) => Record<string, Record<string, (src, args, ctx, info) => any>>

The resolvers object, like the mocks object, can provide a function for each type field. In addition to type fields, resolvers can also specify fields for the Query and Mutation types.

Example:

function resolvers(store) {
  return {
    Query: {
      bookById: () => store.get('Book', id);
    },
    Mutation: {
      updateBookTitle: (_, { bookId, title }) => {
        store.set('Book', id, 'title', title);
        return store.get('Book', id);
      }
    }
  }
}

# fixtures

{ [typeName: string]: Array<any> }

Fixtures allow you to pre-populate the store with entities. Fields not set in fixtures will be generated as usual.

const fixtures = {
  Book: [
    { id: 1, title: 'The amazing story' },
    { id: 2, title: 'A great story' },
    { id: 3, title: 'Greatest letters assembled into words' }
  ],
  User: [
    { id: 1, email: '1@datacamp.com', username: 'User One' },
    { id: 2, email: '2@datacamp.com', username: 'User Two' },
    { id: 3, email: '3@datacamp.com', username: 'User Three' },
  ]
}

# typeDefsExtra

string

typeDefsExtra is an optional property of graphql. It allows to "extend" the graphQL schema with additional types.

This is useful when the schema does not expose enough types and fields for mocking.

# router

(router: Router, store?: Store) => void

The router option can be used to register custom URLs to mock rest endpoints.

The first argument is an Express Router.

If a graphql schema is setup (via graphql.typeDefs or graphql.typeDepsPath), the store will be passed as a second argument.


const myService = {
  router: (router, store) => {
    router.get('/foo', (req, res) => {
      res.send({
        foo: 'bar'
      })
    })
  }
}

Read more about mocking rest endpoints in REST.

# disableFrontpage

Boolean

When set to true, the service's "front page" (ie. the page at http://localhost:1000/{serviceName}) is disabled.

This option allows a router to handle that url itself, when mocking the root url is required.

Datacamp