Mimic your graphql API by quickly and easily generating mock graphql data in the browser and node.js
You want to write maintainable tests in a codebase that interacts with a graphql API and you need mock data. You need mocked data to match the structure of your document which can be a pain given the dynamic and nested nature of graphql queries. You want to have sensible data generated for you by default and the ability to customize on a case by case basis.
MimicQL
is a small but robust solution for generating mocked graphql data. It
provides functions for generating mock data that will match your query,
mutation, and fragment definition structures. It gives you the ability to define
the way your graphql schema should resolve and execute queries, mutations, AND
fragments against it.
This module is distributed via npm which is bundled with node and
should be installed as one of your project's devDependencies
:
npm install --save-dev mimicQL
or
for installation via yarn
yarn add --dev mimicQL
First create a file where your mocker instance will live. To initialize your mocker you need to pass a JSON schema into the mock factory generator exposed from mimicQL.
// mocker.js
import MockFactory from "mimicQL"
import schemaJson from "path/to/schema.json"
export default new MockFactory(schemaJson)
At this point you can generate mock data but without supplying default mock resolvers but your data will consist of only default values for each type. You will more than likely want to have some sensible defaults.
To do that we'll want to define mock resolvers. The documentation on what constitutes a mock resolver can be found here.
// resolvers/Rocket.js
import faker from "faker"
const MockRocket = () => {
return {
id: () => `rocket-${faker.random.uuid()}`,
name: () => `rocket-${faker.random.word()}`,
type: () => `rocket-${faker.random.word()}`,
}
}
export default MockRocket
Generally you only want to define values for the shallow properties on an
object. You'll leave value definition for nested types to the resolver in charge
of that type. For example if a Launch
has a rocket: Rocket
field you should
leave the definition for rocket
to the Rocket
resolver.
Head back to the mocker and add the new mock Rocket
resolver so it can use it
for its defaults.
// mocker.js
import MockFactory from 'mimicQL'
import schemaJson from 'path/to/schema.json'
import Rocket from './resolvers/Rocket'
export default new MockFactory(
schemaJson,
{ mocks: { Rocket }
)
Now with a valid graphql document we can generate some sensible mock data.
import gql from "graphql-tag"
import mocker from "./mocker"
const query = gql`
query Rockets($id: ID!) {
rockets {
id
name
type
}
}
`
const mockedRocketsQuery = mocker.mockQuery(query)
/**
* [
* {
* id: 'rocket-<uuid>',
* name: 'rocket-<word>',
* type: 'rocket-<word>',
* __typename: 'Rocket'
* },
* {
* id: 'rocket-<uuid>',
* name: 'rocket-<word>',
* type: 'rocket-<word>',
* __typename: 'Rocket'
* },
* ]
*/
TODO