import Promise from 'bluebird'
import {EventEmitter} from 'events'
import mocks from 'mocks'
import proxyquire from 'proxyquire'
import pathLib from 'path'
import _ from 'lodash'
import from from 'core-js/library/fn/array/from'

import helper from '../../lib/helper'
import config from '../../lib/config'

// create an array of pattern objects from given strings
var patterns = (...strings) => strings.map((str) => new config.Pattern(str))

function pathsFrom (files) {
  return _.map(from(files), 'path')
}

function findFile (path, files) {
  return from(files).find((file) => file.path === path)
}

var PATTERN_LIST = {
  '/some/*.js': ['/some/a.js', '/some/b.js'],
  '*.txt': ['/c.txt', '/a.txt', '/b.txt'],
  '/a.*': ['/a.txt']
}

var MG = {
  statCache: {
    '/some/a.js': {mtime: new Date()},
    '/some/b.js': {mtime: new Date()},
    '/a.txt': {mtime: new Date()},
    '/b.txt': {mtime: new Date()},
    '/c.txt': {mtime: new Date()}
  }
}
var mockFs = mocks.fs.create({
  some: {
    '0.js': mocks.fs.file('2012-04-04'),
    'a.js': mocks.fs.file('2012-04-04'),
    'b.js': mocks.fs.file('2012-05-05'),
    'd.js': mocks.fs.file('2012-05-05')
  },
  folder: {
    'x.js': mocks.fs.file(0)
  },
  'a.txt': mocks.fs.file(0),
  'b.txt': mocks.fs.file(0),
  'c.txt': mocks.fs.file(0),
  'a.js': mocks.fs.file('2012-01-01')
})

describe('FileList', () => {
  var list
  var emitter
  var preprocess
  var patternList
  var mg
  var modified
  var glob
  var List = list = emitter = preprocess = patternList = mg = modified = glob = null

  beforeEach(() => {})

  describe('files', () => {
    beforeEach(() => {
      patternList = PATTERN_LIST
      mg = MG
      preprocess = sinon.spy((file, done) => process.nextTick(done))
      emitter = new EventEmitter()

      glob = {
        Glob: (pattern, opts) => ({
          found: patternList[pattern],
          statCache: mg.statCache
        })
      }

      List = proxyquire('../../lib/file-list', {
        helper: helper,
        glob: glob,
        path: pathLib.posix,
        'graceful-fs': mockFs
      })
    })

    it('returns a flat array of served files', () => {
      list = new List(patterns('/some/*.js'), [], emitter, preprocess)

      return list.refresh().then(() => {
        expect(list.files.served).to.have.length(2)
      })
    })

    it('returns a unique set', () => {
      list = new List(patterns('/a.*', '*.txt'), [], emitter, preprocess)

      return list.refresh().then(() => {
        expect(list.files.served).to.have.length(3)
        expect(pathsFrom(list.files.served)).to.contain('/a.txt', '/b.txt', '/c.txt')
      })
    })

    it('returns only served files', () => {
      var files = [
        new config.Pattern('/a.*', true),        // served: true
        new config.Pattern('/some/*.js', false) // served: false
      ]

      list = new List(files, [], emitter, preprocess)

      return list.refresh().then(() => {
        expect(pathsFrom(list.files.served)).to.eql(['/a.txt'])
      })
    })

    it('marks no cache files', () => {
      var files = [
        new config.Pattern('/a.*'),        // nocach: false
        new config.Pattern('/some/*.js', true, true, true, true) // nocache: true
      ]

      list = new List(files, [], emitter, preprocess)

      return list.refresh().then(() => {
        expect(pathsFrom(list.files.served)).to.deep.equal([
          '/a.txt',
          '/some/a.js',
          '/some/b.js'
        ])
        expect(preprocess).to.have.been.calledOnce
        expect(list.files.served[0].doNotCache).to.be.false
        expect(list.files.served[1].doNotCache).to.be.true
        expect(list.files.served[2].doNotCache).to.be.true
      })
    })

    it('returns a flat array of included files', () => {
      var files = [
        new config.Pattern('/a.*', true, false), // included: false
        new config.Pattern('/some/*.js') // included: true
      ]

      list = new List(files, [], emitter, preprocess)

      return list.refresh().then(() => {
        expect(pathsFrom(list.files.included)).not.to.contain('/a.txt')
        expect(pathsFrom(list.files.included)).to.deep.equal([
          '/some/a.js',
          '/some/b.js'
        ])
      })
    })
  })

  describe('_isExcluded', () => {
    beforeEach(() => {
      preprocess = sinon.spy((file, done) => process.nextTick(done))
      emitter = new EventEmitter()
    })

    it('returns undefined when no match is found', () => {
      list = new List([], ['hello.js', 'world.js'], emitter, preprocess)
      expect(list._isExcluded('hello.txt')).to.be.undefined
      expect(list._isExcluded('/hello/world/i.js')).to.be.undefined
    })

    it('returns the first match if it finds one', () => {
      list = new List([], ['*.js', '**/*.js'], emitter, preprocess)
      expect(list._isExcluded('world.js')).to.be.eql('*.js')
      expect(list._isExcluded('/hello/world/i.js')).to.be.eql('**/*.js')
    })
  })

  describe('_isIncluded', () => {
    beforeEach(() => {
      preprocess = sinon.spy((file, done) => process.nextTick(done))
      emitter = new EventEmitter()
    })

    it('returns undefined when no match is found', () => {
      list = new List(patterns('*.js'), [], emitter, preprocess)
      expect(list._isIncluded('hello.txt')).to.be.undefined
      expect(list._isIncluded('/hello/world/i.js')).to.be.undefined
    })

    it('returns the first match if it finds one', () => {
      list = new List(patterns('*.js', '**/*.js'), [], emitter, preprocess)
      expect(list._isIncluded('world.js').pattern).to.be.eql('*.js')
      expect(list._isIncluded('/hello/world/i.js').pattern).to.be.eql('**/*.js')
    })
  })

  describe('_exists', () => {
    beforeEach(() => {
      patternList = _.cloneDeep(PATTERN_LIST)
      mg = _.cloneDeep(MG)

      preprocess = sinon.spy((file, done) => process.nextTick(done))
      emitter = new EventEmitter()

      glob = {
        Glob: (pattern, opts) => ({
          found: patternList[pattern],
          statCache: mg.statCache
        })
      }

      List = proxyquire('../../lib/file-list', {
        helper: helper,
        glob: glob,
        path: pathLib.posix,
        'graceful-fs': mockFs
      })

      list = new List(patterns('/some/*.js', '*.txt'), [], emitter, preprocess)

      return list.refresh()
    })

    it('returns false when no match is found', () => {
      expect(list._exists('/some/s.js')).to.be.false
      expect(list._exists('/hello/world.ex')).to.be.false
    })

    it('returns true when a match is found', () => {
      expect(list._exists('/some/a.js')).to.be.true
      expect(list._exists('/some/b.js')).to.be.true
    })
  })

  describe('refresh', () => {
    beforeEach(() => {
      patternList = _.cloneDeep(PATTERN_LIST)
      mg = _.cloneDeep(MG)
      preprocess = sinon.spy((file, done) => process.nextTick(done))
      emitter = new EventEmitter()

      glob = {
        Glob: (pattern, opts) => ({
          found: patternList[pattern],
          statCache: mg.statCache
        })
      }

      List = proxyquire('../../lib/file-list', {
        helper: helper,
        glob: glob,
        path: pathLib.posix,
        'graceful-fs': mockFs
      })

      list = new List(patterns('/some/*.js', '*.txt'), [], emitter, preprocess, 100)
    })

    it('resolves patterns', () => {
      return list.refresh().then((files) => {
        expect(list.buckets.size).to.equal(2)

        var first = pathsFrom(list.buckets.get('/some/*.js'))
        var second = pathsFrom(list.buckets.get('*.txt'))

        expect(first).to.contain('/some/a.js', '/some/b.js')
        expect(second).to.contain('/a.txt', '/b.txt', '/c.txt')
      })
    })

    it('uses the file from the first matcher if two matchers match the same file', () => {
      list = new List(patterns('/a.*', '*.txt'), [], emitter, preprocess, 100)
      return list.refresh().then(() => {
        var first = pathsFrom(list.buckets.get('/a.*'))
        var second = pathsFrom(list.buckets.get('*.txt'))

        expect(first).to.contain('/a.txt')
        expect(second).not.to.contain('/a.txt')
      })
    })

    it('cancels refreshs', () => {
      var checkResult = (files) => {
        expect(_.map(files.served, 'path')).to.contain('/some/a.js', '/some/b.js', '/some/c.js')
      }

      var p1 = list.refresh().then(checkResult)
      patternList['/some/*.js'].push('/some/c.js')
      mg.statCache['/some/c.js'] = {mtime: new Date(Date.now() + 5000)}
      var p2 = list.refresh().then(checkResult)
      var called = false
      var callback = (data) => {
        expect(called).to.be.false
        expect(data.served[0].mtime.toString()).to.not.equal(data.served[2].mtime.toString())
        expect(data.served[0].mtime.toString()).to.equal(data.served[1].mtime.toString())
        called = true
      }
      list._emitter.on('file_list_modified', callback)

      return Promise.all([p1, p2]).then(() => {
        list._emitter.removeListener('file_list_modified', callback)
      })
    })

    it('sets the mtime for all files', () => {
      return list.refresh().then((files) => {
        var bucket = list.buckets.get('/some/*.js')

        var file1 = findFile('/some/a.js', bucket)
        var file2 = findFile('/some/b.js', bucket)

        expect(file1.mtime).to.be.eql(mg.statCache['/some/a.js'].mtime)
        expect(file2.mtime).to.be.eql(mg.statCache['/some/b.js'].mtime)
      })
    })

    it('sets the mtime for relative patterns', () => {
      list = new List(patterns('/some/world/../*.js', '*.txt'), [], emitter, preprocess)

      return list.refresh().then((files) => {
        var bucket = list.buckets.get('/some/world/../*.js')

        var file1 = findFile('/some/a.js', bucket)
        var file2 = findFile('/some/b.js', bucket)

        expect(file1.mtime).to.be.eql(mg.statCache['/some/a.js'].mtime)
        expect(file2.mtime).to.be.eql(mg.statCache['/some/b.js'].mtime)
      })
    })

    it('should sort files within buckets and keep order of patterns (buckets)', () => {
      // /(a.*      ) => /a.txt                   [MATCH in *.txt as well]
      // /some/*.(js) => /some/a.js, /some/b.js   [/some/b.js EXCLUDED]
      // *.(txt     ) => /c.txt, a.txt, b.txt     [UNSORTED]
      list = new List(patterns('/a.*', '/some/*.js', '*.txt'), ['**/b.js'], emitter, preprocess)

      return list.refresh().then((files) => {
        expect(pathsFrom(files.served)).to.deep.equal([
          '/a.txt',
          '/some/a.js',
          '/b.txt',
          '/c.txt'
        ])
      })
    })

    it('ingores excluded files', () => {
      list = new List(patterns('*.txt'), ['/a.*', '**/b.txt'], emitter, preprocess)

      return list.refresh().then((files) => {
        var bucket = pathsFrom(list.buckets.get('*.txt'))

        expect(bucket).to.contain('/c.txt')
        expect(bucket).not.to.contain('/a.txt')
        expect(bucket).not.to.contain('/b.txt')
      })
    })

    it('does not glob urls and sets the isUrl flag', () => {
      list = new List(patterns('http://some.com'), [], emitter, preprocess)

      return list.refresh()
        .then((files) => {
          var bucket = list.buckets.get('http://some.com')
          var file = findFile('http://some.com', bucket)

          expect(file).to.have.property('isUrl', true)
        }
      )
    })

    it('preprocesses all files', () => {
      return list.refresh().then((files) => {
        expect(preprocess.callCount).to.be.eql(5)
      })
    })

    it('fails when a preprocessor fails', () => {
      preprocess = sinon.spy((file, next) => {
        next(new Error('failing'), null)
      })

      list = new List(patterns('/some/*.js'), [], emitter, preprocess)

      return list.refresh().catch((err) => {
        expect(err.message).to.be.eql('failing')
      })
    })

    it('fires modified before resolving promise after subsequent calls', () => {
      var modified = sinon.stub()
      emitter.on('file_list_modified', modified)

      return list.refresh().then(() => {
        expect(modified).to.have.been.calledOnce
      })
        .then(() => {
          list.refresh().then(() => {
            expect(modified).to.have.been.calledTwice
          })
        })
    })
  })

  describe('reload', () => {
    beforeEach(() => {
      preprocess = sinon.spy((file, done) => process.nextTick(done))
      emitter = new EventEmitter()
      list = new List(patterns('/some/*.js', '*.txt'), [], emitter, preprocess)
    })

    it('refreshes, even when a refresh is already happening', () => {
      sinon.spy(list, '_refresh')

      return Promise.all([
        list.refresh(),
        list.reload(patterns('*.txt'), [])
      ])
        .then(() => {
          expect(list._refresh).to.have.been.calledTwice
        }
      )
    })
  })

  describe('addFile', () => {
    var clock = null

    beforeEach(() => {
      patternList = PATTERN_LIST
      mg = MG

      preprocess = sinon.spy((file, done) => process.nextTick(done))
      emitter = new EventEmitter()

      glob = {
        Glob: (pattern, opts) => ({
          found: patternList[pattern],
          statCache: mg.statCache
        })
      }

      clock = sinon.useFakeTimers()
      // This hack is needed to ensure lodash is using the fake timers
      // from sinon
      List = proxyquire('../../lib/file-list', {
        lodash: _.runInContext(),
        helper: helper,
        glob: glob,
        'graceful-fs': mockFs,
        path: pathLib.posix,
        bluebird: Promise
      })

      list = new List(patterns('/some/*.js', '*.txt'), ['/secret/*.txt'], emitter, preprocess, 100)
    })

    afterEach(() => {
      clock.restore()
      Promise.setScheduler((fn) => process.nextTick(fn))
    })

    it('does not add excluded files', () => {
      return list.refresh().then((before) => {
        return list.addFile('/secret/hello.txt').then((files) => {
          expect(files.served).to.be.eql(before.served)
        })
      })
    })

    it('does not add already existing files', () => {
      return list.refresh().then((before) => {
        return list.addFile('/some/a.js').then((files) => {
          expect(files.served).to.be.eql(before.served)
        })
      })
    })

    it('does not add unmatching files', () => {
      return list.refresh().then((before) => {
        return list.addFile('/some/a.ex').then((files) => {
          expect(files.served).to.be.eql(before.served)
        })
      })
    })

    it('adds the file to the correct bucket', () => {
      return list.refresh().then((before) => {
        return list.addFile('/some/d.js').then((files) => {
          expect(pathsFrom(files.served)).to.contain('/some/d.js')
          var bucket = list.buckets.get('/some/*.js')
          expect(pathsFrom(bucket)).to.contain('/some/d.js')
        })
      })
    })

    it('fires "file_list_modified"', () => {
      var modified = sinon.stub()
      emitter.on('file_list_modified', modified)

      return list.refresh().then(() => {
        modified.reset()

        return list.addFile('/some/d.js').then(() => {
          clock.tick(101)
          expect(modified).to.have.been.calledOnce
        })
      })
    })

    it('ignores quick double "add"', () => {
      // On linux fs.watch (chokidar with usePolling: false) fires "add" event twice.
      // This checks that we only stat and preprocess the file once.

      return list.refresh().then(() => {
        preprocess.reset()
        sinon.spy(mockFs, 'stat')

        return Promise.all([
          list.addFile('/some/d.js'),
          list.addFile('/some/d.js')
        ]).then(() => {
          expect(preprocess).to.have.been.calledOnce
          expect(mockFs.stat).to.have.been.calledOnce
        })
      })
    })

    it('sets the proper mtime of the new file', () => {
      list = new List(patterns('/a.*'), [], emitter, preprocess)

      return list.refresh().then(() => {
        return list.addFile('/a.js').then((files) => {
          expect(findFile('/a.js', files.served).mtime).to.eql(new Date('2012-01-01'))
        })
      })
    })

    it('preprocesses the added file', () => {
      // MATCH: /a.txt
      list = new List(patterns('/a.*'), [], emitter, preprocess)
      return list.refresh().then((files) => {
        preprocess.reset()
        return list.addFile('/a.js').then(() => {
          expect(preprocess).to.have.been.calledOnce
          expect(preprocess.args[0][0].originalPath).to.eql('/a.js')
        })
      })
    })
  })

  describe('changeFile', () => {
    var clock = null

    beforeEach(() => {
      patternList = PATTERN_LIST
      mg = MG
      Promise.setScheduler((fn) => fn())

      preprocess = sinon.spy((file, done) => process.nextTick(done))
      emitter = new EventEmitter()

      glob = {
        Glob: (pattern, opts) => ({
          found: patternList[pattern],
          statCache: mg.statCache
        })
      }

      clock = sinon.useFakeTimers()
      // This hack is needed to ensure lodash is using the fake timers
      // from sinon
      List = proxyquire('../../lib/file-list', {
        lodash: _.runInContext(),
        helper: helper,
        glob: glob,
        'graceful-fs': mockFs,
        path: pathLib.posix,
        bluebird: Promise
      })

      mockFs._touchFile('/some/a.js', '2012-04-04')
      mockFs._touchFile('/some/b.js', '2012-05-05')
    })

    afterEach(() => {
      clock.restore()
      Promise.setScheduler((fn) => process.nextTick(fn))
    })

    it('updates mtime and fires "file_list_modified"', () => {
      // MATCH: /some/a.js, /some/b.js
      list = new List(patterns('/some/*.js', '/a.*'), [], emitter, preprocess, 100)
      var modified = sinon.stub()
      emitter.on('file_list_modified', modified)

      return list.refresh().then((files) => {
        mockFs._touchFile('/some/b.js', '2020-01-01')
        modified.reset()

        return list.changeFile('/some/b.js').then((files) => {
          clock.tick(101)
          expect(modified).to.have.been.calledOnce
          expect(findFile('/some/b.js', files.served).mtime).to.be.eql(new Date('2020-01-01'))
        })
      })
    })

    it('does not fire "file_list_modified" if no matching file is found', () => {
      // MATCH: /some/a.js
      list = new List(patterns('/some/*.js', '/a.*'), ['/some/b.js'], emitter, preprocess)

      var modified = sinon.stub()
      emitter.on('file_list_modified', modified)

      return list.refresh().then((files) => {
        mockFs._touchFile('/some/b.js', '2020-01-01')
        modified.reset()

        return list.changeFile('/some/b.js').then(() => {
          expect(modified).to.not.have.been.called
        })
      })
    })

    it('does not fire "file_list_modified" if mtime has not changed', () => {
      // chokidar on fucking windows sometimes fires event multiple times
      // MATCH: /some/a.js, /some/b.js, /a.txt
      list = new List(patterns('/some/*.js', '/a.*'), [], emitter, preprocess)

      var modified = sinon.stub()
      emitter.on('file_list_modified', modified)

      return list.refresh().then((files) => {
        // not touching the file, stat will return still the same
        modified.reset()

        return list.changeFile('/some/b.js').then(() => {
          expect(modified).not.to.have.been.called
        })
      })
    })

    it('preprocesses the changed file', () => {
      // MATCH: /some/a.js, /some/b.js
      list = new List(patterns('/some/*.js', '/a.*'), [], emitter, preprocess)

      return list.refresh().then((files) => {
        preprocess.reset()
        mockFs._touchFile('/some/a.js', '2020-01-01')
        return list.changeFile('/some/a.js').then(() => {
          expect(preprocess).to.have.been.called
          expect(preprocess.lastCall.args[0]).to.have.property('path', '/some/a.js')
        })
      })
    })
  })

  describe('removeFile', () => {
    var clock = null

    beforeEach(() => {
      patternList = PATTERN_LIST
      mg = MG
      Promise.setScheduler((fn) => fn())

      preprocess = sinon.spy((file, done) => process.nextTick(done))
      emitter = new EventEmitter()

      glob = {
        Glob: (pattern, opts) => ({
          found: patternList[pattern],
          statCache: mg.statCache
        })
      }

      clock = sinon.useFakeTimers()
      // This hack is needed to ensure lodash is using the fake timers
      // from sinon
      List = proxyquire('../../lib/file-list', {
        lodash: _.runInContext(),
        helper: helper,
        glob: glob,
        'graceful-fs': mockFs,
        path: pathLib.posix,
        bluebird: Promise
      })

      modified = sinon.stub()
      emitter.on('file_list_modified', modified)
    })

    afterEach(() => {
      clock.restore()
      Promise.setScheduler((fn) => process.nextTick(fn))
    })

    it('removes the file from the list and fires "file_list_modified"', () => {
      // MATCH: /some/a.js, /some/b.js, /a.txt
      list = new List(patterns('/some/*.js', '/a.*'), [], emitter, preprocess, 100)

      var modified = sinon.stub()
      emitter.on('file_list_modified', modified)

      return list.refresh().then((files) => {
        modified.reset()
        return list.removeFile('/some/a.js')
      }).then((files) => {
        expect(pathsFrom(files.served)).to.be.eql([
          '/some/b.js',
          '/a.txt'
        ])
        clock.tick(101)
        expect(modified).to.have.been.calledOnce
      })
    })

    it('does not fire "file_list_modified" if the file is not in the list', () => {
      // MATCH: /some/a.js, /some/b.js, /a.txt
      list = new List(patterns('/some/*.js', '/a.*'), [], emitter, preprocess)

      return list.refresh().then((files) => {
        modified.reset()
        return list.removeFile('/a.js').then(() => {
          expect(modified).to.not.have.been.called
        })
      })
    })
  })

  describe('batch interval', () => {
    // IMPORTANT: When writing tests for debouncing behaviour, you must wait for the promise
    // returned by list.changeFile or list.addFile. list.removeFile calls self._emitModified()
    // in a different manner and doesn't *need* to be waited on. If you use this behaviour
    // in your tests it can can lead to very confusing results when they are modified or
    // extended.
    //
    // Rule of thumb: Always wait on the promises returned by list.addFile, list.changeFile,
    // and list.removeFile.

    var clock = null

    beforeEach(() => {
      patternList = PATTERN_LIST
      mg = MG
      Promise.setScheduler((fn) => fn())

      preprocess = sinon.spy((file, done) => process.nextTick(done))
      emitter = new EventEmitter()

      glob = {
        Glob: (pattern, opts) => ({
          found: patternList[pattern],
          statCache: mg.statCache
        })
      }

      modified = sinon.stub()
      emitter.on('file_list_modified', modified)

      clock = sinon.useFakeTimers()
      // This hack is needed to ensure lodash is using the fake timers
      // from sinon
      List = proxyquire('../../lib/file-list', {
        lodash: _.runInContext(),
        helper: helper,
        glob: glob,
        'graceful-fs': mockFs,
        path: pathLib.posix,
        bluebird: Promise
      })
    })

    afterEach(() => {
      clock.restore()
      Promise.setScheduler((fn) => process.nextTick(fn))
    })

    it('debounces calls to emitModified', () => {
      list = new List(patterns(), [], emitter, preprocess, 100)

      return list.refresh().then(() => {
        modified.reset()
        list._emitModified()
        clock.tick(99)
        expect(modified).to.not.have.been.called
        list._emitModified()
        clock.tick(2)
        expect(modified).to.not.have.been.called
        clock.tick(97)
        expect(modified).to.not.have.been.called
        clock.tick(2)
        expect(modified).to.have.been.calledOnce
        clock.tick(1000)
        expect(modified).to.have.been.calledOnce
        list._emitModified()
        clock.tick(99)
        expect(modified).to.have.been.calledOnce
        clock.tick(2)
        expect(modified).to.have.been.calledTwice
      })
    })

    it('debounces a single file change', () => {
      list = new List(patterns('/some/*.js', '/a.*'), [], emitter, preprocess, 100)

      return list.refresh().then((files) => {
        modified.reset()
        // Even with no changes, all these files are served
        list.addFile('/some/0.js').then(() => {
          clock.tick(99)
          expect(modified).to.not.have.been.called

          clock.tick(2)
          expect(modified).to.have.been.calledOnce

          files = modified.lastCall.args[0]
          expect(pathsFrom(files.served)).to.be.eql([
            '/some/0.js',
            '/some/a.js',
            '/some/b.js',
            '/a.txt'
          ])
        })
      })
    })

    it('debounces several changes to a file', () => {
      list = new List(patterns('/some/*.js', '/a.*'), [], emitter, preprocess, 100)

      return list.refresh().then((files) => {
        modified.reset()
        list.addFile('/some/0.js').then(() => {
          clock.tick(99)
          expect(modified).to.not.have.been.called

          // Modify file, must change mtime too, or change is ignored
          mockFs._touchFile('/some/0.js', '2020-01-01')
          list.changeFile('/some/0.js').then(() => {
            // Ensure that the debounce timer was reset
            clock.tick(2)
            expect(modified).to.not.have.been.called

            // Ensure that debounce timer fires after 100ms
            clock.tick(99)
            expect(modified).to.have.been.calledOnce

            // Make sure there aren't any lingering debounce calls
            clock.tick(1000)

            // Modify file (one hour later mtime)
            expect(modified).to.have.been.calledOnce
            mockFs._touchFile('/some/0.js', '2020-01-02')
            list.changeFile('/some/0.js').then(() => {
              clock.tick(99)
              expect(modified).to.have.been.calledOnce
              clock.tick(2)
              expect(modified).to.have.been.calledTwice

              // Make sure there aren't any lingering calls
              clock.tick(1000)
              expect(modified).to.have.been.calledTwice
            })
          })
        })
      })
    })

    it('debounces multiple changes until there is quiescence', () => {
      // MATCH: /some/a.js, /some/b.js, /a.txt
      list = new List(patterns('/some/*.js', '/a.*'), [], emitter, preprocess, 100)

      return list.refresh().then((files) => {
        modified.reset()
        mockFs._touchFile('/some/b.js', '2020-01-01')
        list.changeFile('/some/b.js')
        list.removeFile('/some/a.js') // /some/b.js, /a.txt
        list.removeFile('/a.txt')     // /some/b.js
        list.addFile('/a.txt')        // /some/b.js, /a.txt
        list.addFile('/some/0.js').then(() => {     // /some/0.js, /some/b.js, /a.txt
          clock.tick(99)
          expect(modified).to.not.have.been.called
          mockFs._touchFile('/a.txt', '2020-01-01')
          list.changeFile('/a.txt').then(() => {
            clock.tick(2)
            expect(modified).to.not.have.been.called

            clock.tick(100)
            expect(modified).to.have.been.calledOnce

            clock.tick(1000)
            expect(modified).to.have.been.calledOnce

            files = modified.lastCall.args[0]
            expect(pathsFrom(files.served)).to.be.eql([
              '/some/0.js',
              '/some/b.js',
              '/a.txt'
            ])
          })
        })
      })
    })

    it('waits while file preprocessing, if the file was deleted and immediately added', () => {
      list = new List(patterns('/a.*'), [], emitter, preprocess, 100)

      list.refresh().then((files) => {
        preprocess.reset()
        modified.reset()

        // Remove and then immediately add file to the bucket
        list.removeFile('/a.txt')
        list.addFile('/a.txt')

        clock.tick(99)

        expect(preprocess).to.not.have.been.called

        var promise = new Promise((resolve) => {
          emitter.once('file_list_modified', () => _.defer(() => {
            resolve()
          }))
        })

        clock.tick(2)

        return promise
          .then(() => {
            return new Promise((resolve) => {
              _.defer(() => {
                resolve()
              })
            })
          })
          .then(() => {
            expect(preprocess).to.have.been.calledOnce
          })
      })
    })
  })
})
