loopback-context/test/main.test.js

// Copyright IBM Corp. 2016,2018. All Rights Reserved.
// Node module: loopback-context
// This file is licensed under the MIT License.
// License text available at https://opensource.org/licenses/MIT

'use strict';

var asyncV152 = require('async-1.5.2');
var whenV377 = require('when-3.7.7');
var LoopBackContext = require('..');
var Domain = require('domain');
var EventEmitter = require('events').EventEmitter;
var expect = require('./helpers/expect');
var loopback = require('loopback');
var request = require('supertest');

describe('LoopBack Context', function() {
  var runInOtherDomain, runnerInterval;

  before(function setupRunInOtherDomain() {
    var emitterInOtherDomain = new EventEmitter();
    Domain.create().add(emitterInOtherDomain);

    runInOtherDomain = function(fn) {
      emitterInOtherDomain.once('run', fn);
    };

    runnerInterval = setInterval(function() {
      emitterInOtherDomain.emit('run');
    }, 10);
  });

  after(function tearDownRunInOtherDomain() {
    clearInterval(runnerInterval);
  });

  // See the following two items for more details:
  // https://github.com/strongloop/loopback/issues/809
  // https://github.com/strongloop/loopback/pull/337#issuecomment-61680577
  it('preserves callback domain', function(done) {
    var app = loopback({localRegistry: true, loadBuiltinModels: true});
    app.set('remoting', {context: false});
    app.set('legacyExplorer', false);
    app.use(LoopBackContext.perRequest());
    app.use(loopback.rest());
    app.dataSource('db', {connector: 'memory'});

    var TestModel = loopback.createModel({name: 'TestModel'});
    app.model(TestModel, {dataSource: 'db', public: true});

    // function for remote method
    TestModel.test = function(inst, cb) {
      var tmpCtx = LoopBackContext.getCurrentContext();
      if (tmpCtx) tmpCtx.set('data', 'a value stored in context');
      if (process.domain) cb = process.domain.bind(cb); // IMPORTANT
      runInOtherDomain(cb);
    };

    // remote method
    TestModel.remoteMethod('test', {
      accepts: {arg: 'inst', type: 'TestModel'},
      returns: {root: true},
      http: {path: '/test', verb: 'get'},
    });

    // after remote hook
    TestModel.afterRemote('**', function(ctxx, inst, next) {
      var tmpCtx = LoopBackContext.getCurrentContext();
      if (tmpCtx) {
        ctxx.result.data = tmpCtx.get('data');
      } else {
        ctxx.result.data = 'context not available';
      }

      next();
    });

    request(app)
      .get('/TestModels/test')
      .end(function(err, res) {
        if (err) return done(err);

        expect(res.body.data).to.equal('a value stored in context');

        done();
      });
  });

  it('works outside REST middleware', function(done) {
    LoopBackContext.runInContext(function() {
      var ctx = LoopBackContext.getCurrentContext();
      expect(ctx).is.an('object');
      ctx.set('test-key', 'test-value');
      process.nextTick(function() {
        var ctx = LoopBackContext.getCurrentContext();
        expect(ctx).is.an('object');
        expect(ctx.get('test-key')).to.equal('test-value');

        done();
      });
    });
  });

  // Credits for the original idea for this test case to @marlonkjoseph
  // Original source of the POC gist of the idea:
  // https://gist.github.com/marlonkjoseph/f42f3c71f746896a0d4b7279a34ea753
  // Heavily edited by others
  it('keeps context when using waterfall() from async 1.5.2',
    function(done) {
      LoopBackContext.runInContext(function() {
      // Trigger async waterfall callbacks
        asyncV152.waterfall([
          function pushToContext(next) {
            var ctx = LoopBackContext.getCurrentContext();
            expect(ctx).is.an('object');
            ctx.set('test-key', 'test-value');
            next();
          },
          function pullFromContext(next) {
            var ctx = LoopBackContext.getCurrentContext();
            expect(ctx).is.an('object');
            var testValue = ctx && ctx.get('test-key', 'test-value');
            next(null, testValue);
          },
          function verify(testValue, next) {
            expect(testValue).to.equal('test-value');
            next();
          },
        ], done);
      });
    });

  it('handles concurrent then() calls with when v3.7.7 promises & bind option',
    function() {
      return Promise.all([
        runWithPushedValue('test-value-1', {bind: true}),
        runWithPushedValue('test-value-2', {bind: true}),
      ])
        .then(function verify(values) {
          var failureCount = getFailureCount(values);
          expect(failureCount).to.equal(0);
        });
    });

  it('fails once without bind option and when v3.7.7 promises',
    function() {
      return Promise.all([
        runWithPushedValue('test-value-3'),
        runWithPushedValue('test-value-4'),
      ])
        .then(function verify(values) {
          var failureCount = getFailureCount(values);
          expect(failureCount).to.equal(1);
        });
    });

  var timeout = 100;

  function runWithPushedValue(pushedValue, options) {
    return new Promise(function concurrentExecutor(outerResolve, reject) {
      LoopBackContext.runInContext(function pushToContext() {
        var ctx = LoopBackContext.getCurrentContext(options);
        expect(ctx).is.an('object');
        ctx.set('test-key', pushedValue);
        var whenPromise = whenV377().delay(timeout);
        whenPromise.then(function pullFromContextAndReturn() {
          var pulledValue = ctx && ctx.get('test-key');
          outerResolve({
            pulledValue: pulledValue,
            pushedValue: pushedValue,
          });
        }).catch(reject);
      });
    });
  }

  function getFailureCount(values) {
    var failureCount = 0;
    values.forEach(function(v) {
      if (v.pulledValue !== v.pushedValue) {
        failureCount++;
      }
    });
    return failureCount;
  }

  it('doesn\'t mix up req\'s in chains of ' +
  'Express-middleware-like func\'s if next() cb is bound',
  function() {
    return Promise.all([
      runWithRequestId('test-value-5', true),
      runWithRequestId('test-value-6', true),
    ])
      .then(function verify(values) {
        var failureCount = getFailureCount(values);
        expect(failureCount).to.equal(0);
      });
  });

  it('fails & mixes up ctx among requests in mw chains if next() cb is unbound',
    function() {
      return Promise.all([
        runWithRequestId('test-value-7'),
        runWithRequestId('test-value-8'),
      ])
        .then(function verify(values) {
          var failureCount = getFailureCount(values);
          expect(failureCount).to.equal(1);
        });
    });

  function runWithRequestId(pushedValue, bindNextCb) {
    return new Promise(function chainExecutor(outerResolve, reject) {
      LoopBackContext.runInContext(function concurrentChain() {
        function middlewareBreakingCls(req, res, next) {
          var ctx = LoopBackContext.getCurrentContext({bind: true});
          if (bindNextCb) {
            next = ctx.bind(next);
          }
          ctx.set('test-key', pushedValue);
          var whenPromise = whenV377().delay(timeout);
          whenPromise.then(next).catch(reject);
        };

        function middlewareReadingContext(req, res, next) {
          var ctx = LoopBackContext.getCurrentContext({bind: true});
          var pulledValue = ctx && ctx.get('test-key');
          next(null, pulledValue);
        };

        // Run the chain
        var req = null;
        var res = null;
        middlewareBreakingCls(req, res, function(err) {
          if (err) return reject(err);

          middlewareReadingContext(req, res, function(err, result) {
            if (err) return reject(err);

            outerResolve({
              pulledValue: result,
              pushedValue: pushedValue,
            });
          });
        });
      });
    });
  }
});