graphql-codegen-typescript-mock-data

Description

GraphQL Codegen Plugin for building mock data based on the schema.

Installation

yarn add -D graphql-codegen-typescript-mock-data

Configuration

typesFile (string, defaultValue: null)

Defines the file path containing all GraphQL types. This file can also be generated through graphql-codgen

addTypename (boolean, defaultValue: false)

Adds __typename property to mock data

terminateCircularRelationships (boolean, defaultValue: false)

When enabled, prevents circular relationships from triggering infinite recursion. After the first resolution of a specific type in a particular call stack, subsequent resolutions will return an empty object cast to the correct type.

prefix (string, defaultValue: a for constants & an for vowels)

The prefix to add to the mock function name. Cannot be empty since it will clash with the associated typescript definition from @graphql-codegen/typescript

enumValues (string, defaultValue: pascal-case#pascalCase)

Changes the case of the enums. Accepts upper-case#upperCase, pascal-case#pascalCase or keep

typenames (string, defaultValue: pascal-case#pascalCase)

Changes the case of the enums. Accepts upper-case#upperCase, pascal-case#pascalCase or keep

scalars ({ [Scalar: string]: ScalarDefinition }, defaultValue: undefined)

Allows you to define mappings for your custom scalars. Allows you to map any GraphQL Scalar to a casual embedded generator (string or function key) with optional arguments

Examples With arguments

plugins:
  - typescript-mock-data:
      scalars:
        Date: # gets translated to casual.date('YYYY-MM-DD')
          generator: date
          arguments: 'YYYY-MM-DD'

With multiple arguments

plugins:
  - typescript-mock-data:
      scalars:
        PaginatedAmount: # gets translated to casual.integer(-100, 100)
          generator: integer
          arguments:
            - -100
            - 100

Shorthand if you don't have arguments

plugins:
  - typescript-mock-data:
      scalars:
        Date: date # gets translated to casual.date()

Custom value generator

plugins:
  - add: "import { arrayBufferGenerator } from '../generators';"
  - typescript-mock-data:
      scalars:
        ArrayBuffer: arrayBufferGenerator()

typesPrefix (string, defaultValue: '')

Useful if you have globally exported types under a certain namespace. e.g If the types file is something like this

declare namespace Api {
 type User {
  ...
 }
}

Setting the typesPrefix to Api. will create the following mock data

export const aUser = (overrides?: Partial<Api.User>): Api.User => {

Example of usage

codegen.yml

overwrite: true
schema: schema.graphql
generates:
  src/generated-types.ts:
    plugins:
      - 'typescript'
  src/mocks/generated-mocks.ts:
    plugins:
      - typescript-mock-data:
          typesFile: '../generated-types.ts'
          enumValues: upper-case#upperCase
          typenames: keep
          scalars:
            AWSTimestamp: unix_time # gets translated to casual.unix_time

Example or generated code

Given the following schema:

scalar AWSTimestamp

type Avatar {
  id: ID!
  url: String!
}

type User {
  id: ID!
  login: String!
  avatar: Avatar
  status: Status!
  updatedAt: AWSTimestamp
}

type Query {
  user: User!
}

input UpdateUserInput {
  id: ID!
  login: String
  avatar: Avatar
}

enum Status {
  ONLINE
  OFFLINE
}

type Mutation {
  updateUser(user: UpdateUserInput): User
}

The code generated will look like:

export const anAvatar = (overrides?: Partial<Avatar>): Avatar => {
  return {
    id: overrides && overrides.hasOwnProperty('id') ? overrides.id! : '0550ff93-dd31-49b4-8c38-ff1cb68bdc38',
    url: overrides && overrides.hasOwnProperty('url') ? overrides.url! : 'aliquid',
  };
};

export const anUpdateUserInput = (overrides?: Partial<UpdateUserInput>): UpdateUserInput => {
  return {
    id: overrides && overrides.hasOwnProperty('id') ? overrides.id! : '1d6a9360-c92b-4660-8e5f-04155047bddc',
    login: overrides && overrides.hasOwnProperty('login') ? overrides.login! : 'qui',
    avatar: overrides && overrides.hasOwnProperty('avatar') ? overrides.avatar! : anAvatar(),
  };
};

export const aUser = (overrides?: Partial<User>): User => {
  return {
    id: overrides && overrides.hasOwnProperty('id') ? overrides.id! : 'a5756f00-41a6-422a-8a7d-d13ee6a63750',
    login: overrides && overrides.hasOwnProperty('login') ? overrides.login! : 'libero',
    avatar: overrides && overrides.hasOwnProperty('avatar') ? overrides.avatar! : anAvatar(),
    status: overrides && overrides.hasOwnProperty('status') ? overrides.status! : Status.Online,
    updatedAt: overrides && overrides.hasOwnProperty('updatedAt') ? overrides.updatedAt! : 1458071232,
  };
};

Usage in tests

Those helper functions can be used in our unit tests:

const user = aUser({ login: 'johndoe' });

// will create a user object with `login` property overridden to `johndoe`

Dealing with Timezone

If some properties use generated dates, the result could different depending on the timezone of your machine.

To force a timezone, you can set environment variable TZ:

TZ=UTC graphql-codegen

This will force the timezone to UTC, whatever the timezone of your machine or CI

Contributing

Feel free to open issues and pull requests. We always welcome support from the community.

To run this project locally:

• Use Node >= 10
• Make sure that you have the latest Yarn version (https://yarnpkg.com/lang/en/docs/install/)
• Clone this repo using git clone
• Run yarn
• Run yarn build to build the package
• Run yarn test to make sure everything works

License

MIT