overleaf/libraries/metrics/test/unit/js/timeAsyncMethodTests.js

/*
 * decaffeinate suggestions:
 * DS102: Remove unnecessary code created because of implicit returns
 * DS207: Consider shorter variations of null checks
 * Full docs: https://github.com/decaffeinate/decaffeinate/blob/master/docs/suggestions.md
 */
const chai = require('chai')
const { expect } = chai
const path = require('path')
const modulePath = path.join(__dirname, '../../../timeAsyncMethod.js')
const SandboxedModule = require('sandboxed-module')
const sinon = require('sinon')

describe('timeAsyncMethod', function () {
  beforeEach(function () {
    this.Timer = { done: sinon.stub() }
    this.TimerConstructor = sinon.stub().returns(this.Timer)
    this.metrics = {
      Timer: this.TimerConstructor,
      inc: sinon.stub(),
    }
    this.timeAsyncMethod = SandboxedModule.require(modulePath, {
      requires: {
        './index': this.metrics,
      },
    })

    return (this.testObject = {
      nextNumber(n, callback) {
        return setTimeout(() => callback(null, n + 1), 100)
      },
    })
  })

  it('should have the testObject behave correctly before wrapping', function (done) {
    return this.testObject.nextNumber(2, (err, result) => {
      expect(err).to.not.exist
      expect(result).to.equal(3)
      return done()
    })
  })

  it('should wrap method without error', function (done) {
    this.timeAsyncMethod(
      this.testObject,
      'nextNumber',
      'someContext.TestObject'
    )
    return done()
  })

  it('should transparently wrap method invocation in timer', function (done) {
    this.timeAsyncMethod(
      this.testObject,
      'nextNumber',
      'someContext.TestObject'
    )
    return this.testObject.nextNumber(2, (err, result) => {
      expect(err).to.not.exist
      expect(result).to.equal(3)
      expect(this.TimerConstructor.callCount).to.equal(1)
      expect(this.Timer.done.callCount).to.equal(1)
      return done()
    })
  })

  it('should increment success count', function (done) {
    this.metrics.inc = sinon.stub()
    this.timeAsyncMethod(
      this.testObject,
      'nextNumber',
      'someContext.TestObject'
    )
    return this.testObject.nextNumber(2, (err, result) => {
      if (err) {
        return done(err)
      }
      expect(this.metrics.inc.callCount).to.equal(1)
      expect(
        this.metrics.inc.calledWith('someContext_result', 1, {
          method: 'TestObject_nextNumber',
          status: 'success',
        })
      ).to.equal(true)
      return done()
    })
  })

  describe('when base method produces an error', function () {
    beforeEach(function () {
      this.metrics.inc = sinon.stub()
      return (this.testObject.nextNumber = function (n, callback) {
        return setTimeout(() => callback(new Error('woops')), 100)
      })
    })

    it('should propagate the error transparently', function (done) {
      this.timeAsyncMethod(
        this.testObject,
        'nextNumber',
        'someContext.TestObject'
      )
      return this.testObject.nextNumber(2, (err, result) => {
        expect(err).to.exist
        expect(err).to.be.instanceof(Error)
        expect(result).to.not.exist
        return done()
      })
    })

    return it('should increment failure count', function (done) {
      this.timeAsyncMethod(
        this.testObject,
        'nextNumber',
        'someContext.TestObject'
      )
      return this.testObject.nextNumber(2, (err, result) => {
        expect(err).to.exist
        expect(this.metrics.inc.callCount).to.equal(1)
        expect(
          this.metrics.inc.calledWith('someContext_result', 1, {
            method: 'TestObject_nextNumber',
            status: 'failed',
          })
        ).to.equal(true)
        return done()
      })
    })
  })

  describe('when a logger is supplied', function () {
    beforeEach(function () {
      return (this.logger = { log: sinon.stub() })
    })

    return it('should also call logger.log', function (done) {
      this.timeAsyncMethod(
        this.testObject,
        'nextNumber',
        'someContext.TestObject',
        this.logger
      )
      return this.testObject.nextNumber(2, (err, result) => {
        expect(err).to.not.exist
        expect(result).to.equal(3)
        expect(this.TimerConstructor.callCount).to.equal(1)
        expect(this.Timer.done.callCount).to.equal(1)
        expect(this.logger.log.callCount).to.equal(1)
        return done()
      })
    })
  })

  describe('when the wrapper cannot be applied', function () {
    beforeEach(function () {})

    return it('should raise an error', function () {
      const badWrap = () => {
        return this.timeAsyncMethod(
          this.testObject,
          'DEFINITELY_NOT_A_REAL_METHOD',
          'someContext.TestObject'
        )
      }
      return expect(badWrap).to.throw(
        /^.*expected object property 'DEFINITELY_NOT_A_REAL_METHOD' to be a function.*$/
      )
    })
  })

  return describe('when the wrapped function is not using a callback', function () {
    beforeEach(function () {
      this.realMethod = sinon.stub().returns(42)
      return (this.testObject.nextNumber = this.realMethod)
    })

    it('should not throw an error', function () {
      this.timeAsyncMethod(
        this.testObject,
        'nextNumber',
        'someContext.TestObject'
      )
      const badCall = () => {
        return this.testObject.nextNumber(2)
      }
      return expect(badCall).to.not.throw(Error)
    })

    return it('should call the underlying method', function () {
      this.timeAsyncMethod(
        this.testObject,
        'nextNumber',
        'someContext.TestObject'
      )
      const result = this.testObject.nextNumber(12)
      expect(this.realMethod.callCount).to.equal(1)
      expect(this.realMethod.calledWith(12)).to.equal(true)
      return expect(result).to.equal(42)
    })
  })
})