graphql-typed-client/src/testHelpers/render.ts

A tool that generates a strongly typed client library for any GraphQL endpoint. The client allows writing GraphQL queries as plain JS objects (with type safety, awesome code completion experience, custom scalar type mapping, type guards and more)

import {
  buildClientSchema,
  buildSchema,
  getIntrospectionQuery,
  graphql,
  GraphQLNamedType,
  GraphQLSchema,
  IntrospectionQuery,
} from 'graphql'
import { BuiltInParserName } from 'prettier'
import { RenderContext } from '../render/common/RenderContext'
import { readFileFromPath } from '../helpers/files'

export interface TypeRenderer {
  (type: GraphQLNamedType, ctx: RenderContext): void
}

export interface SchemaRenderer {
  (schema: GraphQLSchema, ctx: RenderContext): void
}

export const toClientSchema = async (schemaGql: string) => {
  const schema = buildSchema(schemaGql)

  const introspectionResponse = await graphql<IntrospectionQuery>(schema, getIntrospectionQuery())

  if (!introspectionResponse.data) {
    throw new Error(JSON.stringify(introspectionResponse.errors))
  }

  return buildClientSchema(introspectionResponse.data)
}

export const schemaRenderTest = async (schemaGql: string, renderer: SchemaRenderer, parser?: BuiltInParserName) => {
  const schema = await toClientSchema(schemaGql)

  const ctx = new RenderContext(schema)

  renderer(schema, ctx)

  return ctx.toCode(parser)
}

export const typeRenderTest = async (
  schemaGql: string,
  renderer: TypeRenderer,
  typeNames: string[],
  parser?: BuiltInParserName,
) => {
  const schema = await toClientSchema(schemaGql)

  const ctx = new RenderContext(schema)

  typeNames.forEach(typeName => {
    const type = schema.getType(typeName)

    if (!type) {
      throw new Error(`type ${typeName} is not defined in the schema`)
    }

    renderer(type, ctx)
  })

  return ctx.toCode(parser)
}

export const typeRenderTestCase = async (
  dirName: string,
  file: string,
  renderer: TypeRenderer,
  typeNames: string[],
  output = false,
) => {
  const [gql, ts] = await Promise.all([
    readFileFromPath([dirName, `cases/${file}.graphql`]),
    readFileFromPath([dirName, `cases/${file}.case.ts`]),
  ])

  const actualTs = await typeRenderTest(gql, renderer, typeNames, 'typescript')

  if (output) {
    console.log(actualTs)
    throw new Error('test case did not run')
  } else {
    expect(actualTs).toBe(ts)
  }
}