Support mocking GraphQL API

[kettanaito]

I suggest that MSW would provide a standard set of request handlers for mocking a GraphQL API.

Motivation

• GraphQL is an adopted technology, mocking which would be beneficial for users
• Mock-driven GraphQL development may be a good try-out for the technology, as you don't have to write any server-side code before deciding to fully adopt GraphQL

Features

• Ability to target GraphQL operations based on type (query/mutation) and name
• Ability to mock response data and errors according to GraphQL specification

Usage

Mocking a query

import { composeMocks, graphql } from 'msw'

const { start } = composeMocks(
  graphql.query({ operation: 'GetProjectDetail' }, (req, res, ctx) => {
    const { projectPath } = req.variables

    return res(
      ctx.data({
        data: {
          name: 'mocked-project'
        },
      }),
    )
  }),
)

start()

Mocking a mutation

import { composeMocks, graphql } from 'msw'

const { start } = composeMocks(
  graphql.mutation({ operation: 'GetProjectDetail' }, (req, res, ctx) => {
    return res(
      ctx.data({
        data: {
          name: 'mocked-project'
        },
      }),
    )
  }),
)

start()