node.js 代理从另一个模块所需的模块获取存根异步函数

Question

测试中的模块：

'use strict';
const config = require('config');
const q      = require('q');
class RedisAccess {
    static getValue(key) {
        let deferred = q.defer();
        if (config.redis.disableInteraction) {
            deferred.resolve();
            return deferred.promise;
        }
        config.redisClient.get(key, function handleResults(err, result) {
        ...
        return deferred.promise;
    }        
}
exports = module.exports = RedisAccess;

测试：

var proxyquire = require('proxyquire').noPreserveCache();
var assert = require('assert');
var readdirError = new Error('some error');
var redisClientStub = { };
var calledBack;
// Override redisClient used by RedisAccess.js.
var redisClientProxy = proxyquire('../../../lib/data/redis/RedisAccess.js', { 'config' : redisClientStub });
// Test redisClient.get(...) to retrieve value given key using proxyquire for redisClient.
redisClientStub.redisClient.get = function (key, cb) {
    cb(null, 'hello world'); 
};
calledBack = false;
// Test redisClient getValue async function.
redisClientProxy.getValue('some_key', function (err, value) {
    assert.equal(err, null);
    assert.equal('value', 'hello world');
    callback = true;
});

执行测试时的错误是：

redisClientStub.redisClient.get = function （key， cb） { ^

类型错误： 无法设置未定义的属性"get"

如何正确存根 config.redisClient.get（...） 函数？

Answer 1

我想

通了。我不得不放一个"存根中的存根"来存根config.redisClient.get（）函数：

// Proxyquire allows unobstrusively overriding dependencies during testing. 
// Override config used by RedisAccess.js.
var configStub = { 
  redisClient : {
    createClient : function (port, address) {
      // redis-mock-js used instead.
    },
    get : function (key, cb) {
      if(key === 'test-rejected') {
        cb(new Error('test-rejected'), 'rejected-promise');
      } 
      else if(key === 'test-true') {
        cb(null, true);
      }
      else if(key === 'test-get-valid') {
        cb(null, 'valid-value');
      }
      else {
        cb(new Error('Should not have gotten here!'), 'value');
      }
    },
  }
};

这允许我构建这个代理：

var redisAccessProxy = proxyquire('lib/data/redis/RedisAccess.js', { 'config' : configStub });

并使用 redisClient.get（...） 的代理函数运行此测试，该函数在 RedisAccess.getValue（...） 中调用：

var val = redisAccessProxy.getValue('test-get-valid');
assert.equal(val.isFulfilled(), true);
assert.equal(val.isRejected(), false);
assert.equal(val, 'valid-value');