merge-options.js

// @flow

function getStubs (optionStubs, config) {
  if (optionStubs ||
    (config.stubs && Object.keys(config.stubs).length > 0)) {
    if (Array.isArray(optionStubs)) {
      return [
        ...optionStubs,
        ...Object.keys(config.stubs || {})]
    } else {
      return {
        ...config.stubs,
        ...optionStubs
      }
    }
  }
}

function getMocks (optionMocks, config) {
  if (optionMocks ||
    (config.mocks && Object.keys(config.mocks).length > 0)) {
    if (Array.isArray(optionMocks)) {
      return [
        ...optionMocks,
        ...Object.keys(config.mocks || {})]
    } else {
      return {
        ...config.mocks,
        ...optionMocks
      }
    }
  }
}

export function mergeOptions (
  options: Options,
  config: Options
): Options {
  return {
    ...options,
    stubs: getStubs(options.stubs, config),
    mocks: getMocks(options.mocks, config)
  }
}