mock-resource.js

import { configs } from '../mappersmith'
import MockRequest from './mock-request'
import Request from '../request'

const VALUE_NOT_MATCHED = '<MAPPERSMITH_VALUE_NOT_MATCHED>'

/**
 * @param {Integer} id
 * @param {Object} client - the client generated by {@link forge}
 */
function MockResource(id, client) {
  if (!client || !client._manifest) {
    throw new Error('[Mappersmith Test] "mockClient" received an invalid client')
  }

  this.id = id
  this.manifest = client._manifest
  this.resourceName = null
  this.mockName = null
  this.methodName = null
  this.requestParams = {}
  this.responseData = null
  this.responseHandler = null
  this.responseHeaders = {}
  this.responseStatus = 200
  this.responseStatusHandler = null
  this.mockRequest = null
  this.asyncFinalRequest = null
  this.pendingMiddlewareExecution = true
}

MockResource.prototype = {
  /**
   * @return {MockResource}
   */
  resource(resourceName) {
    this.resourceName = resourceName
    return this
  },

  /**
   * Names you mock instance for debugging purposes.
   * @return {MockResource}
   */
  named(mockName) {
    this.mockName = mockName
    return this
  },

  /**
   * Creates a name for the mock based on the client id and the resource name.
   * @returns {String}
   */
  getName() {
    const { mockName, manifest, resourceName, id } = this
    const { clientId } = manifest || {}
    if (mockName) return mockName

    const resourcePart = resourceName || id
    if (clientId) {
      return `${clientId} - ${resourcePart}`
    }

    return resourceName ? `${resourceName} - ${id}` : id
  },

  /**
   * @return {MockResource}
   */
  method(methodName) {
    this.methodName = methodName
    return this
  },

  /**
   * @return {MockResource}
   */
  with(requestParams) {
    this.requestParams = requestParams
    return this
  },

  /**
   * @return {MockResource}
   */
  headers(responseHeaders) {
    this.responseHeaders = responseHeaders
    return this
  },

  /**
   * @return {MockResource}
   */
  status(responder) {
    if (typeof responder === 'function') {
      this.responseStatusHandler = responder
    } else {
      this.responseStatus = responder
    }
    return this
  },

  /**
   * @return {MockResource}
   */
  response(responder) {
    if (typeof responder === 'function') {
      this.responseHandler = responder
    } else {
      this.responseData = responder
    }
    return this
  },

  /**
   * @return {Promise<MockAssert>}
   */
  assertObjectAsync() {
    return this.createAsyncRequest().then((finalRequest) => {
      this.asyncFinalRequest = finalRequest
      this.pendingMiddlewareExecution = false
      return this.toMockRequest().assertObject()
    })
  },

  /**
   * @return {MockAssert}
   */
  assertObject() {
    // The middleware "prepareRequest" phase is always async, so the middleware
    // stack will never run when assertObject is used
    return this.toMockRequest().assertObject()
  },

  /**
   * @return {MockRequest}
   */
  toMockRequest() {
    const finalRequest = this.asyncFinalRequest ? this.asyncFinalRequest : this.createRequest()

    const responseStatus = this.responseStatusHandler || this.responseStatus

    if (!this.mockRequest) {
      this.mockRequest = new MockRequest(this.id, {
        mockName: this.getName(),
        method: finalRequest.method(),
        url: this.generateUrlMatcher(finalRequest),
        body: finalRequest.body(),
        headers: finalRequest.headers(),
        response: {
          status: responseStatus,
          headers: this.responseHeaders,
          body: this.responseData,
          handler: this.responseHandler,
        },
      })
    }

    return this.mockRequest
  },

  /**
   * @private
   */
  generateUrlMatcher(finalRequest) {
    const params = finalRequest.params()
    const hasParamMatchers = Object.keys(params).find((key) => typeof params[key] === 'function')

    if (!hasParamMatchers) {
      return finalRequest.url()
    }

    const urlMatcher = (requestUrl, requestParams) => {
      const additionalParams = this.evaluateParamMatchers(params, requestParams)
      const testRequest = finalRequest.enhance({ params: additionalParams })
      return testRequest.url() === requestUrl
    }

    return urlMatcher
  },

  /**
   * @private
   */
  executeMiddlewareStack() {
    return this.createAsyncRequest().then((finalRequest) => {
      this.asyncFinalRequest = finalRequest

      if (this.mockRequest) {
        const urlMatcher = this.generateUrlMatcher(finalRequest)
        this.mockRequest.url = urlMatcher
        this.mockRequest.body = finalRequest.body()
        this.pendingMiddlewareExecution = false
      }
    })
  },

  /**
   * @private
   */
  evaluateParamMatchers(mockParams, requestParams) {
    return Object.keys(mockParams).reduce((obj, key) => {
      const matcher = mockParams[key]

      if (typeof matcher !== 'function') {
        return obj
      }

      const value = requestParams[key]
      // Only evaluate if key was provided in request params.
      // Otherwise we always consider it not to match.
      if (key in requestParams && matcher(value)) {
        obj[key] = value
      } else {
        obj[key] = VALUE_NOT_MATCHED
      }

      return obj
    }, {})
  },

  /**
   * @private
   * It never runs the middleware stack
   */
  createRequest() {
    const methodDescriptor = this.manifest.createMethodDescriptor(
      this.resourceName,
      this.methodName
    )
    return new Request(methodDescriptor, this.requestParams)
  },

  /**
   * @private
   * Always runs the middleware stack
   */
  createAsyncRequest() {
    const methodDescriptor = this.manifest.createMethodDescriptor(
      this.resourceName,
      this.methodName
    )
    const initialRequest = new Request(methodDescriptor, this.requestParams)
    const middleware = this.manifest.createMiddleware({
      resourceName: this.resourceName,
      resourceMethod: this.methodName,
      mockRequest: true,
    })
    const abort = (error) => {
      throw error
    }
    const getInitialRequest = () => configs.Promise.resolve(initialRequest)
    const prepareRequest = middleware.reduce(
      (next, middleware) => () =>
        configs.Promise.resolve().then(() => middleware.prepareRequest(next, abort)),
      getInitialRequest
    )

    return prepareRequest()
  },
}

export default MockResource