diff --git a/.travis.yml b/.travis.yml
index 2303d5e71..966d2dc08 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,7 +1,5 @@
 language: node_js
-node_js:
-  - "8"
-  - "6"
+node_js: "lts/*"
 jobs:
   include:
     - stage: test
diff --git a/rollup.config.js b/rollup.config.js
index a91dfecca..86dc2a8b8 100644
--- a/rollup.config.js
+++ b/rollup.config.js
@@ -50,7 +50,7 @@ export default [{
         exclude: [ 'test' ],
         compilerOptions: {
           module: 'ES2015',
-          paths: { 'template': ['src/parser/template-browser'] }
+          paths: { 'src/fs': ['src/fs/browser'] }
         }
       }
     })
@@ -71,7 +71,7 @@ export default [{
         exclude: [ 'test' ],
         compilerOptions: {
           module: 'ES2015',
-          paths: { 'template': ['src/parser/template-browser'] }
+          paths: { 'src/fs': ['src/fs/browser'] }
         }
       }
     }),
diff --git a/src/builtin/filters/index.ts b/src/builtin/filters/index.ts
index e47aa10d8..c3bdc588a 100644
--- a/src/builtin/filters/index.ts
+++ b/src/builtin/filters/index.ts
@@ -1,4 +1,3 @@
-import { assign } from 'src/util/underscore'
 import html from './html'
 import str from './string'
 import math from './math'
@@ -7,6 +6,4 @@ import array from './array'
 import date from './date'
 import obj from './object'
 
-const filters = assign({}, html, str, math, url, date, obj, array)
-
-export default filters
+export default { ...html, ...str, ...math, ...url, ...date, ...obj, ...array }
diff --git a/src/builtin/tags/include.ts b/src/builtin/tags/include.ts
index 45d4f6298..615d65d84 100644
--- a/src/builtin/tags/include.ts
+++ b/src/builtin/tags/include.ts
@@ -45,7 +45,7 @@ export default {
     if (this.with) {
       hash[filepath] = evalValue(this.with, scope)
     }
-    const templates = await this.liquid.getTemplate(filepath, scope.opts.root)
+    const templates = await this.liquid.getTemplate(filepath, scope.opts)
     scope.push(hash)
     const html = await this.liquid.renderer.renderTemplates(templates, scope)
     scope.pop(hash)
diff --git a/src/builtin/tags/layout.ts b/src/builtin/tags/layout.ts
index 8fb229acf..69942e102 100644
--- a/src/builtin/tags/layout.ts
+++ b/src/builtin/tags/layout.ts
@@ -31,7 +31,7 @@ export default {
     if (scope.blocks[''] === undefined) {
       scope.blocks[''] = html
     }
-    const templates = await this.liquid.getTemplate(layout, scope.opts.root)
+    const templates = await this.liquid.getTemplate(layout, scope.opts)
     scope.push(hash)
     scope.blockMode = BlockMode.OUTPUT
     const partial = await this.liquid.renderer.renderTemplates(templates, scope)
diff --git a/src/parser/template-browser.ts b/src/fs/browser.ts
similarity index 69%
rename from src/parser/template-browser.ts
rename to src/fs/browser.ts
index 37aa91eb8..50356b34f 100644
--- a/src/parser/template-browser.ts
+++ b/src/fs/browser.ts
@@ -1,4 +1,5 @@
-import { last, isArray } from '../util/underscore'
+import { last } from '../util/underscore'
+import IFS from './ifs'
 
 function domResolve (root, path) {
   const base = document.createElement('base')
@@ -15,25 +16,17 @@ function domResolve (root, path) {
   return resolved
 }
 
-export function resolve (filepath, root, options) {
-  root = root || options.root
-  if (isArray(root)) {
-    root = root[0]
-  }
-  if (root.length && last(root) !== '/') {
-    root += '/'
-  }
+function resolve (root, filepath, ext) {
+  if (root.length && last(root) !== '/') root += '/'
   const url = domResolve(root, filepath)
   return url.replace(/^(\w+:\/\/[^/]+)(\/[^?]+)/, (str, origin, path) => {
     const last = path.split('/').pop()
-    if (/\.\w+$/.test(last)) {
-      return str
-    }
-    return origin + path + options.extname
+    if (/\.\w+$/.test(last)) return str
+    return origin + path + ext
   })
 }
 
-export async function read (url: string): Promise<string> {
+async function readFile (url: string): Promise<string> {
   return new Promise((resolve, reject) => {
     const xhr = new XMLHttpRequest()
     xhr.onload = () => {
@@ -50,3 +43,9 @@ export async function read (url: string): Promise<string> {
     xhr.send()
   })
 }
+
+async function exists () {
+  return true
+}
+
+export default { readFile, resolve, exists } as IFS
diff --git a/src/fs/ifs.ts b/src/fs/ifs.ts
new file mode 100644
index 000000000..637a0e7c4
--- /dev/null
+++ b/src/fs/ifs.ts
@@ -0,0 +1,5 @@
+export default interface IFS {
+  exists: (filepath?: string) => Promise<boolean>
+  readFile: (filepath:string) => Promise<string>
+  resolve: (root: string, file: string, ext: string) => string
+}
diff --git a/src/fs/node.ts b/src/fs/node.ts
new file mode 100644
index 000000000..7ee93c966
--- /dev/null
+++ b/src/fs/node.ts
@@ -0,0 +1,22 @@
+import * as _ from '../util/underscore'
+import { resolve, extname } from 'path'
+import { stat, readFile } from 'fs'
+import IFS from './ifs'
+
+const statAsync = _.promisify(stat) as (filepath: string) => Promise<object>
+const readFileAsync = _.promisify(readFile) as (filepath: string, encoding: string) => Promise<string>
+
+const fs: IFS = {
+  exists: filepath => {
+    return statAsync(filepath).then(() => true).catch(() => false)
+  },
+  readFile: filepath => {
+    return readFileAsync(filepath, 'utf8')
+  },
+  resolve: (root: string, file: string, ext: string) => {
+    if (!extname(file)) file += ext
+    return resolve(root, file)
+  }
+}
+
+export default fs
diff --git a/src/liquid-options.ts b/src/liquid-options.ts
index bf9ee75c2..84d49f900 100644
--- a/src/liquid-options.ts
+++ b/src/liquid-options.ts
@@ -1,3 +1,5 @@
+import * as _ from './util/underscore'
+
 export interface LiquidOptions {
   /** `root` is a directory or an array of directories to resolve layouts and includes, as well as the filename passed in when calling `.renderFile()`. If an array, the files are looked up in the order they occur in the array. Defaults to `["."]` */
   root?: string | string[]
@@ -23,7 +25,11 @@ export interface LiquidOptions {
   greedy?: boolean
 }
 
-export const defaultOptions: LiquidOptions = {
+export interface NormalizedOptions extends LiquidOptions {
+  root?: string[]
+}
+
+export const defaultOptions: NormalizedOptions = {
   root: ['.'],
   cache: false,
   extname: '',
@@ -36,3 +42,17 @@ export const defaultOptions: LiquidOptions = {
   strict_filters: false,
   strict_variables: false
 }
+
+export function normalize (options: LiquidOptions): NormalizedOptions {
+  options = options || {}
+  if (options.hasOwnProperty('root')) {
+    options.root = normalizeStringArray(options.root)
+  }
+  return options as NormalizedOptions
+}
+
+function normalizeStringArray (value: string | string[]): string[] {
+  if (_.isArray(value)) return value as string[]
+  if (_.isString(value)) return [value as string]
+  return []
+}
diff --git a/src/liquid.ts b/src/liquid.ts
index c559d7f81..e296688f0 100644
--- a/src/liquid.ts
+++ b/src/liquid.ts
@@ -1,6 +1,6 @@
 import Scope from './scope/scope'
 import * as Types from './types'
-import * as template from 'template'
+import fs from 'src/fs'
 import * as _ from './util/underscore'
 import ITemplate from './template/itemplate'
 import Tokenizer from './parser/tokenizer'
@@ -13,19 +13,17 @@ import Value from './template/value'
 import { isTruthy, isFalsy, evalExp, evalValue } from './render/syntax'
 import builtinTags from './builtin/tags'
 import builtinFilters from './builtin/filters'
-import { LiquidOptions, defaultOptions } from './liquid-options'
+import { LiquidOptions, NormalizedOptions, defaultOptions, normalize } from './liquid-options'
 
 export default class Liquid {
-  public options: LiquidOptions
+  public options: NormalizedOptions
   private cache: object
   private parser: Parser
   private renderer: Render
   private tokenizer: Tokenizer
 
-  constructor (options: LiquidOptions = {}) {
-    options = _.assign({}, defaultOptions, options)
-    options.root = normalizeStringArray(options.root)
-
+  constructor (opts: LiquidOptions = {}) {
+    const options = { ...defaultOptions, ...normalize(opts) }
     if (options.cache) {
       this.cache = {}
     }
@@ -42,37 +40,38 @@ export default class Liquid {
     return this.parser.parse(tokens)
   }
   render (tpl: Array<ITemplate>, ctx?: object, opts?: LiquidOptions) {
-    opts = _.assign({}, this.options, opts)
-    const scope = new Scope(ctx, opts)
+    const options = { ...this.options, ...normalize(opts) }
+    const scope = new Scope(ctx, options)
     return this.renderer.renderTemplates(tpl, scope)
   }
   async parseAndRender (html: string, ctx?: object, opts?: LiquidOptions) {
     const tpl = await this.parse(html)
     return this.render(tpl, ctx, opts)
   }
-  async getTemplate (file, root) {
-    const filepath = await template.resolve(file, root, this.options)
-    return this.respectCache(filepath, async () => {
-      const str = await template.read(filepath)
-      return this.parse(str, filepath)
-    })
+  async getTemplate (file, opts?: LiquidOptions) {
+    const options = normalize(opts)
+    const roots = options.root ? [...options.root, ...this.options.root] : this.options.root
+    const paths = roots.map(root => fs.resolve(root, file, this.options.extname))
+
+    for (const filepath of paths) {
+      if (!(await fs.exists(filepath))) continue
+
+      if (this.options.cache && this.cache[filepath]) return this.cache[filepath]
+      const value = this.parse(await fs.readFile(filepath), filepath)
+      if (this.options.cache) this.cache[filepath] = value
+      return value
+    }
+
+    const err = new Error('ENOENT') as any
+    err.message = `ENOENT: Failed to lookup "${file}" in "${roots}"`
+    err.code = 'ENOENT'
+    throw err
   }
   async renderFile (file, ctx?: object, opts?: LiquidOptions) {
-    opts = _.assign({}, opts)
-    const templates = await this.getTemplate(file, opts.root)
+    const options = normalize(opts)
+    const templates = await this.getTemplate(file, options)
     return this.render(templates, ctx, opts)
   }
-  async respectCache (key, getter) {
-    const cacheEnabled = this.options.cache
-    if (cacheEnabled && this.cache[key]) {
-      return this.cache[key]
-    }
-    const value = await getter()
-    if (cacheEnabled) {
-      this.cache[key] = value
-    }
-    return value
-  }
   evalValue (str: string, scope: Scope) {
     return new Value(str, this.options.strict_filters).value(scope)
   }
@@ -85,10 +84,10 @@ export default class Liquid {
   plugin (plugin) {
     return plugin.call(this, Liquid)
   }
-  express (opts: LiquidOptions = {}) {
+  express () {
     const self = this
-    return function (filePath, ctx, cb) {
-      opts.root = this.root
+    return function (filePath: string, ctx: object, cb: (err: Error, html?: string) => void) {
+      const opts = { root: this.root }
       self.renderFile(filePath, ctx, opts).then(html => cb(null, html), cb)
     }
   }
@@ -99,9 +98,3 @@ export default class Liquid {
   static evalValue = evalValue
   static Types = Types
 }
-
-function normalizeStringArray (value) {
-  if (_.isArray(value)) return value
-  if (_.isString(value)) return [value]
-  throw new TypeError('illegal root: ' + value)
-}
diff --git a/src/parser/template.ts b/src/parser/template.ts
deleted file mode 100644
index ef0d4ff7b..000000000
--- a/src/parser/template.ts
+++ /dev/null
@@ -1,31 +0,0 @@
-import * as _ from '../util/underscore'
-import * as path from 'path'
-import { anySeries } from '../util/promise'
-import { stat, readFile } from 'fs'
-
-export const fs = {
-  stat: _.promisify(stat) as ((filepath: string) => Promise<object>),
-  readFile: _.promisify(readFile) as ((filepath: string, encoding: string) => Promise<string>)
-}
-
-export async function resolve (filepath, root, options) {
-  if (!path.extname(filepath)) {
-    filepath += options.extname
-  }
-  root = options.root.concat(root || [])
-  root = _.uniq(root)
-  const paths = root.map(root => path.resolve(root, filepath))
-  return anySeries(paths, async path => {
-    try {
-      await fs.stat(path)
-      return path
-    } catch (e) {
-      e.message = `${e.code}: Failed to lookup ${filepath} in: ${root}`
-      throw e
-    }
-  })
-}
-
-export async function read (filepath): Promise<string> {
-  return fs.readFile(filepath, 'utf8')
-}
diff --git a/src/parser/whitespace-ctrl.ts b/src/parser/whitespace-ctrl.ts
index 65479ac01..27667b48f 100644
--- a/src/parser/whitespace-ctrl.ts
+++ b/src/parser/whitespace-ctrl.ts
@@ -1,11 +1,10 @@
-import { assign } from 'src/util/underscore'
 import DelimitedToken from 'src/parser/delimited-token'
 import Token from 'src/parser/token'
 import TagToken from 'src/parser/tag-token'
 import { LiquidOptions } from 'src/liquid-options'
 
 export default function whiteSpaceCtrl (tokens: Token[], options: LiquidOptions) {
-  options = assign({ greedy: true }, options)
+  options = { greedy: true, ...options }
   let inRaw = false
 
   tokens.forEach((token: Token, i: number) => {
diff --git a/src/scope/scope.ts b/src/scope/scope.ts
index e96ccf7d8..f7f72ea50 100644
--- a/src/scope/scope.ts
+++ b/src/scope/scope.ts
@@ -1,21 +1,16 @@
 import * as _ from '../util/underscore'
 import * as lexical from '../parser/lexical'
 import assert from '../util/assert'
-import { LiquidOptions, defaultOptions } from '../liquid-options'
+import { NormalizedOptions, defaultOptions } from '../liquid-options'
 import BlockMode from './block-mode'
 
 export default class Scope {
-  opts: LiquidOptions
+  opts: NormalizedOptions
   contexts: Array<object>
   blocks: object = {}
   blockMode: BlockMode = BlockMode.OUTPUT
-  constructor (ctx: object = {}, opts: LiquidOptions = defaultOptions) {
-    this.opts = _.assign({
-      dynamicPartials: true,
-      strict_variables: false,
-      strict_filters: false,
-      root: []
-    }, opts)
+  constructor (ctx: object = {}, opts: NormalizedOptions = defaultOptions) {
+    this.opts = { ...defaultOptions, ...opts }
     this.contexts = [ctx || {}]
   }
   getAll () {
@@ -43,10 +38,10 @@ export default class Scope {
       scope = scope[key]
     })
   }
-  unshift (ctx: object): any {
+  unshift (ctx: object) {
     return this.contexts.unshift(ctx)
   }
-  push (ctx: object): any {
+  push (ctx: object) {
     return this.contexts.push(ctx)
   }
   pop (ctx?: object): object {
diff --git a/src/util/error.ts b/src/util/error.ts
index ebb0112f9..42ffc9ba2 100644
--- a/src/util/error.ts
+++ b/src/util/error.ts
@@ -48,7 +48,7 @@ TokenizationError.prototype.constructor = TokenizationError
 export class ParseError extends LiquidError {
   constructor (err, token) {
     super(err, token)
-    _.assign(this, err)
+    this.message = err.message
     super.captureStackTrace(this)
   }
 }
@@ -58,7 +58,7 @@ ParseError.prototype.constructor = ParseError
 export class RenderError extends LiquidError {
   constructor (err, tpl) {
     super(err, tpl.token)
-    _.assign(this, err)
+    this.message = err.message
     super.captureStackTrace(this)
   }
 }
diff --git a/src/util/strftime.ts b/src/util/strftime.ts
index bf4012a31..a4a90ce13 100644
--- a/src/util/strftime.ts
+++ b/src/util/strftime.ts
@@ -35,8 +35,6 @@ const _date = {
     return num + d.getDate()
   },
 
-  // Startday is an integer of which day to start the week measuring from
-  // TODO: that comment was retarted. fix it.
   getWeekOfYear: function (d, startDay) {
     // Skip to startDay of this week
     const now = this.getDayOfYear(d) + (startDay - d.getDay())
diff --git a/test/e2e/express.ts b/test/e2e/express.ts
index fb38ec579..3d0fa3260 100644
--- a/test/e2e/express.ts
+++ b/test/e2e/express.ts
@@ -1,16 +1,19 @@
 import { expect } from 'chai'
 import * as request from 'supertest'
 import * as express from 'express'
-import { mock, restore } from 'test/stub/mockfs'
+import { resolve } from 'path'
 import Liquid from '../..'
 
 describe('express()', function () {
-  var app, engine
+  const root = resolve(__dirname, '../stub/root')
+  const views = resolve(__dirname, '../stub/views')
+  const partials = resolve(__dirname, '../stub/partials')
+  let app, engine
 
   beforeEach(function () {
     app = express()
     engine = new Liquid({
-      root: '/root',
+      root,
       extname: '.html'
     })
 
@@ -24,14 +27,18 @@ describe('express()', function () {
       file: req.params.file
     }))
   })
-  after(restore)
-  it('should render express views', function (done) {
-    mock({ '/views/name.html': 'My name is {{name}}.' })
-    app.set('views', ['/views'])
+  it('should respect express views(array)', function (done) {
+    app.set('views', [views])
     request(app).get('/name')
       .expect('My name is harttle.')
       .expect(200, done)
   })
+  it('should respect express views(string)', function (done) {
+    app.set('views', views)
+    request(app).get('/include/bar')
+      .expect('bar')
+      .expect(200, done)
+  })
   it('should pass error when file not found', function (done) {
     const view = {
       root: []
@@ -49,41 +56,13 @@ describe('express()', function () {
     })
   })
   it('should respect root option when lookup', function (done) {
-    mock({
-      '/root/foo.html': 'foo',
-      '/views/include.html': '{% include file %}'
-    })
-    app.set('views', ['/views'])
+    app.set('views', [views])
     request(app).get('/include/foo')
       .expect('foo')
       .expect(200, done)
   })
   it('should respect express views (Array) when lookup', function (done) {
-    mock({
-      '/views/include.html': '{% include file %}',
-      '/partials/bar.html': 'bar'
-    })
-    app.set('views', ['/views', '/partials'])
-    request(app).get('/include/bar')
-      .expect('bar')
-      .expect(200, done)
-  })
-  it('should respect express views (String) when lookup', function (done) {
-    mock({
-      '/views/include.html': '{% include file %}',
-      '/views/bar.html': 'bar'
-    })
-    app.set('views', '/views')
-    request(app).get('/include/bar')
-      .expect('bar')
-      .expect(200, done)
-  })
-  it('should respect express views (undefined) when lookup', function (done) {
-    const files = {}
-    files[process.cwd() + '/views/include.html'] = '{% include file %}'
-    files[process.cwd() + '/views/bar.html'] = 'bar'
-    mock(files)
-
+    app.set('views', [views, partials])
     request(app).get('/include/bar')
       .expect('bar')
       .expect(200, done)
diff --git a/test/e2e/render-file.ts b/test/e2e/render-file.ts
index 3c7da317b..699ade7b0 100644
--- a/test/e2e/render-file.ts
+++ b/test/e2e/render-file.ts
@@ -1,61 +1,53 @@
-import { expect } from 'chai'
 import Liquid from '../..'
-import { mock, restore } from '../stub/mockfs'
+import { expect, use } from 'chai'
+import * as chaiAsPromised from 'chai-as-promised'
+import { resolve } from 'path'
+
+use(chaiAsPromised)
 
 describe('#renderFile()', function () {
-  var engine
+  const root = resolve(__dirname, '../stub/root')
+  const views = resolve(__dirname, '../stub/views')
+  let engine
   beforeEach(function () {
     engine = new Liquid({
-      root: '/root/',
+      root,
       extname: '.html'
     })
-    mock({
-      '/root/files/bar': 'bar',
-      '/root/files/foo.html': 'foo',
-      '/root/files/name.html': 'My name is {{name}}.',
-      '/un-readable.html': { mode: '0000' }
-    })
   })
-  afterEach(restore)
   it('should render file', async function () {
-    const html = await engine.renderFile('/root/files/foo.html', {})
+    const html = await engine.renderFile(resolve(root, 'foo.html'), {})
     return expect(html).to.equal('foo')
   })
   it('should find files without extname', async function () {
-    var engine = new Liquid({ root: '/root' })
-    const html = await engine.renderFile('/root/files/bar', {})
+    var engine = new Liquid({ root })
+    const html = await engine.renderFile(resolve(root, 'bar'), {})
     return expect(html).to.equal('bar')
   })
   it('should accept relative path', async function () {
-    const html = await engine.renderFile('files/foo.html')
+    const html = await engine.renderFile('foo.html')
     return expect(html).to.equal('foo')
   })
-  it('should resolve array as root', async function () {
-    engine = new Liquid({
-      root: ['/boo', '/root/'],
-      extname: '.html'
-    })
-    const html = await engine.renderFile('files/foo.html')
-    return expect(html).to.equal('foo')
-  })
-  it('should default root to cwd', async function () {
-    var files = {}
-    files[process.cwd() + '/foo.html'] = 'FOO'
-    mock(files)
-
+  it('should traverse root array', async function () {
     engine = new Liquid({
+      root: ['/boo', root],
       extname: '.html'
     })
     const html = await engine.renderFile('foo.html')
-    return expect(html).to.equal('FOO')
+    return expect(html).to.equal('foo')
+  })
+  it('should default root to cwd', async function () {
+    engine = new Liquid()
+    const html = await engine.renderFile('package.json')
+    return expect(html).to.contain('"name": "liquidjs"')
   })
   it('should render file with context', async function () {
-    const html = await engine.renderFile('/root/files/name.html', { name: 'harttle' })
+    const html = await engine.renderFile(resolve(views, 'name.html'), { name: 'harttle' })
     return expect(html).to.equal('My name is harttle.')
   })
   it('should use default extname', async function () {
-    const html = await engine.renderFile('files/name', { name: 'harttle' })
-    return expect(html).to.equal('My name is harttle.')
+    const html = await engine.renderFile(resolve(root, 'foo'))
+    return expect(html).to.equal('foo')
   })
   it('should throw with lookup list when file not exist', function () {
     engine = new Liquid({
@@ -63,10 +55,6 @@ describe('#renderFile()', function () {
       extname: '.html'
     })
     return expect(engine.renderFile('/not/exist.html')).to
-      .be.rejectedWith(/failed to lookup \/not\/exist.html in: \/boo,\/root\//i)
-  })
-  it('should throw when file not readable', function () {
-    return expect(engine.renderFile('/un-readable.html')).to
-      .be.rejectedWith(/EACCES/)
+      .be.rejectedWith(/Failed to lookup "\/not\/exist.html" in "\/boo,\/root\/"/)
   })
 })
diff --git a/test/stub/mockfs.ts b/test/stub/mockfs.ts
index 2ad63f01f..4668bbd60 100644
--- a/test/stub/mockfs.ts
+++ b/test/stub/mockfs.ts
@@ -1,31 +1,34 @@
-import { fs } from 'src/parser/template'
 import { isString } from 'src/util/underscore'
-
-const readFile = fs.readFile
-const stat = fs.stat
+import fs from 'src/fs'
 
 type fileDescriptor = { mode: string, content: string }
 
-export function mock (files: { [path: string]: (string | fileDescriptor) }) {
-  for (const [key, val] of Object.entries(files)) {
+let files: { [path: string]: fileDescriptor } = {}
+const readFile = fs.readFile
+const exists = fs.exists
+
+export function mock (options: { [path: string]: (string | fileDescriptor) }) {
+  for (const [key, val] of Object.entries(options)) {
     files[key] = isString(val)
       ? { mode: '33188', content: val as string }
-      : val
+      : val as fileDescriptor
   }
   fs.readFile = async function (path) {
-    const file = files[path] as fileDescriptor
+    console.log('mock fs read called', path)
+    const file = files[path]
     if (file === undefined) throw new Error('ENOENT')
-    if (file.mode === '000') throw new Error('EACCES')
+    if (file.mode === '0000') throw new Error('EACCES')
     return file.content
   }
-  fs.stat = async function (path) {
-    const file = files[path] as fileDescriptor
-    if (file === undefined) throw new Error('ENOENT')
-    return file
+
+  fs.exists = async function (path) {
+    console.log('mock fs exists called', path)
+    return !!files[path]
   }
 }
 
 export function restore () {
+  files = {}
   fs.readFile = readFile
-  fs.stat = stat
+  fs.exists = exists
 }
diff --git a/test/stub/partials/bar.html b/test/stub/partials/bar.html
new file mode 100644
index 000000000..ba0e162e1
--- /dev/null
+++ b/test/stub/partials/bar.html
@@ -0,0 +1 @@
+bar
\ No newline at end of file
diff --git a/test/stub/render.ts b/test/stub/render.ts
new file mode 100644
index 000000000..fc8f152ea
--- /dev/null
+++ b/test/stub/render.ts
@@ -0,0 +1,18 @@
+import Liquid from 'src/liquid'
+import { expect } from 'chai'
+
+export const liquid = new Liquid()
+
+export const ctx = {
+  date: new Date(),
+  foo: 'bar',
+  arr: [-2, 'a'],
+  obj: { foo: 'bar' },
+  func: function () {},
+  posts: [{ category: 'foo' }, { category: 'bar' }]
+}
+
+export async function test (src, dst) {
+  const html = await liquid.parseAndRender(src, ctx)
+  return expect(html).to.equal(dst)
+}
diff --git a/test/stub/root/bar b/test/stub/root/bar
new file mode 100644
index 000000000..ba0e162e1
--- /dev/null
+++ b/test/stub/root/bar
@@ -0,0 +1 @@
+bar
\ No newline at end of file
diff --git a/test/stub/root/foo.html b/test/stub/root/foo.html
new file mode 100644
index 000000000..191028156
--- /dev/null
+++ b/test/stub/root/foo.html
@@ -0,0 +1 @@
+foo
\ No newline at end of file
diff --git a/test/stub/views/bar.html b/test/stub/views/bar.html
new file mode 100644
index 000000000..ba0e162e1
--- /dev/null
+++ b/test/stub/views/bar.html
@@ -0,0 +1 @@
+bar
\ No newline at end of file
diff --git a/test/stub/views/include.html b/test/stub/views/include.html
new file mode 100644
index 000000000..43ed74df6
--- /dev/null
+++ b/test/stub/views/include.html
@@ -0,0 +1 @@
+{% include file %}
\ No newline at end of file
diff --git a/test/stub/views/name.html b/test/stub/views/name.html
new file mode 100644
index 000000000..6de4c619d
--- /dev/null
+++ b/test/stub/views/name.html
@@ -0,0 +1 @@
+My name is {{name}}.
\ No newline at end of file
diff --git a/test/unit/builtin/filters/array.ts b/test/unit/builtin/filters/array.ts
new file mode 100644
index 000000000..625060511
--- /dev/null
+++ b/test/unit/builtin/filters/array.ts
@@ -0,0 +1,66 @@
+import { test, ctx, liquid } from 'test/stub/render'
+
+describe('filters/array', function () {
+  describe('join', function () {
+    it('should support join', function () {
+      const src = '{% assign beatles = "John, Paul, George, Ringo" | split: ", " %}' +
+        '{{ beatles | join: " and " }}'
+      return test(src, 'John and Paul and George and Ringo')
+    })
+    it('should default separator to space', function () {
+      const src = '{% assign beatles = "John, Paul, George, Ringo" | split: ", " %}' +
+        '{{ beatles | join }}'
+      return test(src, 'John Paul George Ringo')
+    })
+  })
+  it('should support split/last', function () {
+    const src = '{% assign my_array = "zebra, octopus, giraffe, tiger" | split: ", " %}' +
+      '{{ my_array|last }}'
+    return test(src, 'tiger')
+  })
+  it('should support map', function () {
+    return test('{{posts | map: "category"}}', '["foo","bar"]')
+  })
+  it('should support reverse', function () {
+    return test('{{ "Ground control to Major Tom." | split: "" | reverse | join: "" }}',
+      '.moT rojaM ot lortnoc dnuorG')
+  })
+  describe('size', function () {
+    it('should return string length',
+      () => test('{{ "Ground control to Major Tom." | size }}', '28'))
+    it('should return array size', function () {
+      return test('{% assign my_array = "apples, oranges, peaches, plums"' +
+                ' | split: ", " %}{{ my_array | size }}',
+      '4')
+    })
+    it('should also be used with dot notation - string',
+      () => test('{% assign my_string = "Ground control to Major Tom." %}{{ my_string.size }}', '28'))
+    it('should also be used with dot notation - array',
+      () => test('{% assign my_array = "apples, oranges, peaches, plums" | split: ", " %}{{ my_array.size }}', '4'))
+  })
+  describe('slice', function () {
+    it('should slice first char by 0', () => test('{{ "Liquid" | slice: 0 }}', 'L'))
+    it('should slice third char by 2', () => test('{{ "Liquid" | slice: 2 }}', 'q'))
+    it('should slice substr by 2,5', () => test('{{ "Liquid" | slice: 2, 5 }}', 'quid'))
+    it('should slice substr by -3,2', () => test('{{ "Liquid" | slice: -3, 2 }}', 'ui'))
+    it('should support array', () => test('{{ "1,2,3,4" | split: "," | slice: 1,2 | join }}', '2 3'))
+  })
+  it('should support sort', function () {
+    return test('{% assign my_array = "zebra, octopus, giraffe, Sally Snake"' +
+            ' | split: ", " %}' +
+            '{{ my_array | sort | join: ", " }}',
+    'Sally Snake, giraffe, octopus, zebra')
+  })
+  describe('uniq', function () {
+    it('should uniq string list', function () {
+      return test(
+        '{% assign my_array = "ants, bugs, bees, bugs, ants" | split: ", " %}' +
+        '{{ my_array | uniq | join: ", " }}',
+        'ants, bugs, bees'
+      )
+    })
+    it('should uniq falsy value', function () {
+      return test('{{"" | uniq | join: ","}}', '')
+    })
+  })
+})
diff --git a/test/unit/builtin/filters/date.ts b/test/unit/builtin/filters/date.ts
new file mode 100644
index 000000000..0fbd6638d
--- /dev/null
+++ b/test/unit/builtin/filters/date.ts
@@ -0,0 +1,20 @@
+import { test, ctx, liquid } from 'test/stub/render'
+
+describe('filters/date', function () {
+  it('should support date: %a %b %d %Y', function () {
+    const str = ctx.date.toDateString()
+    return test('{{ date | date:"%a %b %d %Y"}}', str)
+  })
+  it('should create a new Date when given "now"', function () {
+    return test('{{ "now" | date: "%Y"}}', (new Date()).getFullYear().toString())
+  })
+  it('should parse as Date when given UTC string', function () {
+    return test('{{ "1991-02-22T00:00:00" | date: "%Y"}}', '1991')
+  })
+  it('should render string as string if not valid', function () {
+    return test('{{ "foo" | date: "%Y"}}', 'foo')
+  })
+  it('should render object as string if not valid', function () {
+    return test('{{ obj | date: "%Y"}}', '{"foo":"bar"}')
+  })
+})
diff --git a/test/unit/builtin/filters/html.ts b/test/unit/builtin/filters/html.ts
new file mode 100644
index 000000000..846329015
--- /dev/null
+++ b/test/unit/builtin/filters/html.ts
@@ -0,0 +1,43 @@
+import { test, ctx, liquid } from 'test/stub/render'
+
+describe('filters/html', function () {
+  describe('escape', function () {
+    it('should escape \' and &', function () {
+      return test('{{ "Have you read \'James & the Giant Peach\'?" | escape }}',
+        'Have you read &#39;James &amp; the Giant Peach&#39;?')
+    })
+    it('should escape normal string', function () {
+      return test('{{ "Tetsuro Takara" | escape }}', 'Tetsuro Takara')
+    })
+    it('should escape function', function () {
+      return test('{{ func | escape }}', 'function () { }')
+    })
+  })
+  describe('escape_once', function () {
+    it('should do escape', () =>
+      test('{{ "1 < 2 & 3" | escape_once }}', '1 &lt; 2 &amp; 3'))
+    it('should not escape twice',
+      () => test('{{ "1 &lt; 2 &amp; 3" | escape_once }}', '1 &lt; 2 &amp; 3'))
+  })
+  describe('strip_html', function () {
+    it('should strip all tags', function () {
+      return test('{{ "Have <em>you</em> read <cite><a href=&quot;https://en.wikipedia.org/wiki/Ulysses_(novel)&quot;>Ulysses</a></cite>?" | strip_html }}',
+        'Have you read Ulysses?')
+    })
+    it('should strip all comment tags', function () {
+      return test('{{ "<!--Have you read-->Ulysses?" | strip_html }}',
+        'Ulysses?')
+    })
+    it('should strip all style tags and their contents', function () {
+      return test('{{ "<style>cite { font-style: italic; }</style><cite>Ulysses<cite>?" | strip_html }}',
+        'Ulysses?')
+    })
+    it('should strip all scripts tags and their contents', function () {
+      return test('{{ "<script async>console.log(\'hello world\')</script><cite>Ulysses<cite>?" | strip_html }}',
+        'Ulysses?')
+    })
+    it('should strip until empty', function () {
+      return test('{{"<br/><br />< p ></p></ p >" | strip_html }}', '')
+    })
+  })
+})
diff --git a/test/unit/builtin/filters/math.ts b/test/unit/builtin/filters/math.ts
new file mode 100644
index 000000000..942302e67
--- /dev/null
+++ b/test/unit/builtin/filters/math.ts
@@ -0,0 +1,64 @@
+import { test, ctx, liquid } from 'test/stub/render'
+
+describe('filters/math', function () {
+  describe('abs', function () {
+    it('should return 3 for -3', () => test('{{ -3 | abs }}', '3'))
+    it('should return 2 for arr[0]', () => test('{{ arr[0] | abs }}', '2'))
+    it('should return convert string', () => test('{{ "-3" | abs }}', '3'))
+  })
+  describe('ceil', function () {
+    it('should return "2" for 1.2', () => test('{{ 1.2 | ceil }}', '2'))
+    it('should return "2" for 2.0', () => test('{{ 2.0 | ceil }}', '2'))
+    it('should return "4" for 3.5', () => test('{{ "3.5" | ceil }}', '4'))
+    it('should return "184" for 183.357', () => test('{{ 183.357 | ceil }}', '184'))
+  })
+  describe('divided_by', function () {
+    it('should return 2 for 4,2', () => test('{{4 | divided_by: 2}}', '2'))
+    it('should return 4 for 16,4', () => test('{{16 | divided_by: 4}}', '4'))
+    it('should return 1 for 5,3', () => test('{{5 | divided_by: 3}}', (5 / 3).toString()))
+    it('should convert string to number', () => test('{{"6" | divided_by: "3"}}', '2'))
+  })
+  describe('floor', function () {
+    it('should return "1" for 1.2', () => test('{{ 1.2 | floor }}', '1'))
+    it('should return "2" for 2.0', () => test('{{ 2.0 | floor }}', '2'))
+    it('should return "183" for 183.357', () => test('{{ 183.357 | floor }}', '183'))
+    it('should return "3" for 3.5', () => test('{{ "3.5" | floor }}', '3'))
+  })
+  describe('minus', function () {
+    it('should return "2" for 4,2', () => test('{{ 4 | minus: 2 }}', '2'))
+    it('should return "12" for 16,4', () => test('{{ 16 | minus: 4 }}', '12'))
+    it('should return "171.357" for 183.357,12',
+      () => test('{{ 183.357 | minus: 12 }}', '171.357'))
+    it('should convert first arg as number', () => test('{{ "4" | minus: 1 }}', '3'))
+    it('should convert both args as number', () => test('{{ "4" | minus: "1" }}', '3'))
+  })
+  describe('modulo', function () {
+    it('should return "1" for 3,2', () => test('{{ 3 | modulo: 2 }}', '1'))
+    it('should return "3" for 24,7', () => test('{{ 24 | modulo: 7 }}', '3'))
+    it('should return "3.357" for 183.357,12',
+      () => test('{{ 183.357 | modulo: 12 }}', '3.357'))
+    it('should convert string', () => test('{{ "24" | modulo: "7" }}', '3'))
+  })
+  describe('plus', function () {
+    it('should return "6" for 4,2', () => test('{{ 4 | plus: 2 }}', '6'))
+    it('should return "20" for 16,4', () => test('{{ 16 | plus: 4 }}', '20'))
+    it('should return "195.357" for 183.357,12',
+      () => test('{{ 183.357 | plus: 12 }}', '195.357'))
+    it('should convert first arg as number', () => test('{{ "4" | plus: 2 }}', '6'))
+    it('should convert both args as number', () => test('{{ "4" | plus: "2" }}', '6'))
+  })
+  describe('round', function () {
+    it('should return "1" for 1.2', () => test('{{1.2|round}}', '1'))
+    it('should return "3" for 2.7', () => test('{{2.7|round}}', '3'))
+    it('should return "183.36" for 183.357,2',
+      () => test('{{183.357|round: 2}}', '183.36'))
+    it('should convert string to number', () => test('{{"2.7"|round}}', '3'))
+  })
+  describe('times', function () {
+    it('should return "6" for 3,2', () => test('{{ 3 | times: 2 }}', '6'))
+    it('should return "168" for 24,7', () => test('{{ 24 | times: 7 }}', '168'))
+    it('should return "2200.284" for 183.357,12',
+      () => test('{{ 183.357 | times: 12 }}', '2200.284'))
+    it('should convert string to number', () => test('{{ "24" | times: "7" }}', '168'))
+  })
+})
diff --git a/test/unit/builtin/filters/object.ts b/test/unit/builtin/filters/object.ts
new file mode 100644
index 000000000..671edf27f
--- /dev/null
+++ b/test/unit/builtin/filters/object.ts
@@ -0,0 +1,8 @@
+import { test, ctx, liquid } from 'test/stub/render'
+
+describe('filters/object', function () {
+  describe('default', function () {
+    it('should use default when falsy', () => test('{{false |default: "a"}}', 'a'))
+    it('should not use default when truthy', () => test('{{true |default: "a"}}', 'true'))
+  })
+})
diff --git a/test/unit/builtin/filters/string.ts b/test/unit/builtin/filters/string.ts
new file mode 100644
index 000000000..c8baf3435
--- /dev/null
+++ b/test/unit/builtin/filters/string.ts
@@ -0,0 +1,161 @@
+import { test, ctx, liquid } from 'test/stub/render'
+
+describe('filters/string', function () {
+  describe('append', function () {
+    it('should return "-3abc" for -3, "abc"',
+      () => test('{{ -3 | append: "abc" }}', '-3abc'))
+    it('should return "abar" for "a",foo', () => test('{{ "a" | append: foo }}', 'abar'))
+  })
+  describe('capitalize', function () {
+    it('should capitalize first', () => test('{{ "i am good" | capitalize }}', 'I am good'))
+  })
+  describe('concat', function () {
+    it('should concat arrays', () => test(`
+      {%- assign fruits = "apples, oranges, peaches" | split: ", " -%}
+      {%- assign vegetables = "carrots, turnips, potatoes" | split: ", " -%}
+
+      {%- assign everything = fruits | concat: vegetables -%}
+
+      {%- for item in everything -%}
+      - {{ item }}
+      {% endfor -%}`, `- apples
+      - oranges
+      - peaches
+      - carrots
+      - turnips
+      - potatoes
+      `))
+    it('should support chained concat', () => test(`
+      {%- assign fruits = "apples, oranges, peaches" | split: ", " -%}
+      {%- assign vegetables = "carrots, turnips, potatoes" | split: ", " -%}
+      {%- assign furniture = "chairs, tables, shelves" | split: ", " -%}
+      {%- assign everything = fruits | concat: vegetables | concat: furniture -%}
+
+      {%- for item in everything -%}
+      - {{ item }}
+      {% endfor -%}`, `- apples
+      - oranges
+      - peaches
+      - carrots
+      - turnips
+      - potatoes
+      - chairs
+      - tables
+      - shelves
+      `))
+  })
+  describe('downcase', function () {
+    it('should return "parker moore" for "Parker Moore"',
+      () => test('{{ "Parker Moore" | downcase }}', 'parker moore'))
+    it('should return "apple" for "apple"',
+      () => test('{{ "apple" | downcase }}', 'apple'))
+  })
+  describe('split', function () {
+    it('should support split/first', function () {
+      const src = '{% assign my_array = "apples, oranges, peaches, plums" | split: ", " %}' +
+        '{{ my_array | first }}'
+      return test(src, 'apples')
+    })
+  })
+  it('should support upcase', () => test('{{ "Parker Moore" | upcase }}', 'PARKER MOORE'))
+  it('should support lstrip', function () {
+    const src = '{{ "          So much room for activities!          " | lstrip }}'
+    return test(src, 'So much room for activities!          ')
+  })
+  it('should support string_with_newlines', function () {
+    const src = '{% capture string_with_newlines %}\n' +
+            'Hello\n' +
+            'there\n' +
+            '{% endcapture %}' +
+            '{{ string_with_newlines | newline_to_br }}'
+    const dst = '<br />' +
+            'Hello<br />' +
+            'there<br />'
+    return test(src, dst)
+  })
+  it('should support prepend', function () {
+    return test('{% assign url = "liquidmarkup.com" %}' +
+            '{{ "/index.html" | prepend: url }}',
+    'liquidmarkup.com/index.html')
+  })
+  it('should support remove', function () {
+    return test('{{ "I strained to see the train through the rain" | remove: "rain" }}',
+      'I sted to see the t through the ')
+  })
+  it('should support remove_first', function () {
+    return test('{{ "I strained to see the train through the rain" | remove_first: "rain" }}',
+      'I sted to see the train through the rain')
+  })
+  it('should support replace', function () {
+    return test('{{ "Take my protein pills and put my helmet on" | replace: "my", "your" }}',
+      'Take your protein pills and put your helmet on')
+  })
+  it('should support replace_first', function () {
+    return test('{% assign my_string = "Take my protein pills and put my helmet on" %}\n' +
+            '{{ my_string | replace_first: "my", "your" }}',
+    '\nTake your protein pills and put my helmet on')
+  })
+  it('should support rstrip', function () {
+    return test('{{ "          So much room for activities!          " | rstrip }}',
+      '          So much room for activities!')
+  })
+  it('should support split', function () {
+    return test('{% assign beatles = "John, Paul, George, Ringo" | split: ", " %}' +
+            '{% for member in beatles %}' +
+            '{{ member }} ' +
+            '{% endfor %}',
+    'John Paul George Ringo ')
+  })
+  it('should support strip', function () {
+    return test('{{ "          So much room for activities!          " | strip }}',
+      'So much room for activities!')
+  })
+  it('should support strip_newlines', function () {
+    return test('{% capture string_with_newlines %}\n' +
+            'Hello\nthere\n{% endcapture %}' +
+            '{{ string_with_newlines | strip_newlines }}',
+    'Hellothere')
+  })
+  describe('truncate', function () {
+    it('should truncate when string too long', function () {
+      return test('{{ "Ground control to Major Tom." | truncate: 20 }}',
+        'Ground control to...')
+    })
+    it('should not truncate when string not long enough', function () {
+      return test('{{ "Ground control to Major Tom." | truncate: 80 }}',
+        'Ground control to Major Tom.')
+    })
+    it('should truncate with custom ellipsis', function () {
+      return test('{{ "Ground control to Major Tom." | truncate: 25,", and so on" }}',
+        'Ground control, and so on')
+    })
+    it('should truncate with empty custom ellipsis', function () {
+      return test('{{ "Ground control to Major Tom." | truncate: 20, "" }}',
+        'Ground control to Ma')
+    })
+    it('should not truncate when short enough', function () {
+      return test('{{ "12345" | truncate: 5 }}', '12345')
+    })
+    it('should default to 16', function () {
+      return test('{{ "1234567890abcdefghi" | truncate }}', '1234567890abc...')
+    })
+  })
+  describe('truncatewords', function () {
+    it('should truncate when too many words', function () {
+      return test('{{ "Ground control to Major Tom." | truncatewords: 3 }}',
+        'Ground control to...')
+    })
+    it('should not truncate when not enough words', function () {
+      return test('{{ "Ground control to Major Tom." | truncatewords: 8 }}',
+        'Ground control to Major Tom.')
+    })
+    it('should truncate with custom ellipsis', function () {
+      return test('{{ "Ground control to Major Tom." | truncatewords: 3, "--" }}',
+        'Ground control to--')
+    })
+    it('should truncate with empty custom ellipsis', function () {
+      return test('{{ "Ground control to Major Tom." | truncatewords: 3, "" }}',
+        'Ground control to')
+    })
+  })
+})
diff --git a/test/unit/builtin/filters/url.ts b/test/unit/builtin/filters/url.ts
new file mode 100644
index 000000000..1c791c8db
--- /dev/null
+++ b/test/unit/builtin/filters/url.ts
@@ -0,0 +1,15 @@
+import { test, ctx, liquid } from 'test/stub/render'
+
+describe('filters/url', function () {
+  describe('url_decode', function () {
+    it('should decode %xx and +',
+      () => test('{{ "%27Stop%21%27+said+Fred" | url_decode }}', "'Stop!' said Fred"))
+  })
+
+  describe('url_encode', function () {
+    it('should encode @',
+      () => test('{{ "john@liquid.com" | url_encode }}', 'john%40liquid.com'))
+    it('should encode <space>',
+      () => test('{{ "Tetsuro Takara" | url_encode }}', 'Tetsuro+Takara'))
+  })
+})
diff --git a/test/unit/tags/assign.ts b/test/unit/builtin/tags/assign.ts
similarity index 100%
rename from test/unit/tags/assign.ts
rename to test/unit/builtin/tags/assign.ts
diff --git a/test/unit/tags/capture.ts b/test/unit/builtin/tags/capture.ts
similarity index 100%
rename from test/unit/tags/capture.ts
rename to test/unit/builtin/tags/capture.ts
diff --git a/test/unit/tags/case.ts b/test/unit/builtin/tags/case.ts
similarity index 100%
rename from test/unit/tags/case.ts
rename to test/unit/builtin/tags/case.ts
diff --git a/test/unit/tags/comment.ts b/test/unit/builtin/tags/comment.ts
similarity index 100%
rename from test/unit/tags/comment.ts
rename to test/unit/builtin/tags/comment.ts
diff --git a/test/unit/tags/cycle.ts b/test/unit/builtin/tags/cycle.ts
similarity index 100%
rename from test/unit/tags/cycle.ts
rename to test/unit/builtin/tags/cycle.ts
diff --git a/test/unit/tags/decrement.ts b/test/unit/builtin/tags/decrement.ts
similarity index 100%
rename from test/unit/tags/decrement.ts
rename to test/unit/builtin/tags/decrement.ts
diff --git a/test/unit/tags/for.ts b/test/unit/builtin/tags/for.ts
similarity index 100%
rename from test/unit/tags/for.ts
rename to test/unit/builtin/tags/for.ts
diff --git a/test/unit/tags/if.ts b/test/unit/builtin/tags/if.ts
similarity index 100%
rename from test/unit/tags/if.ts
rename to test/unit/builtin/tags/if.ts
diff --git a/test/unit/tags/include.ts b/test/unit/builtin/tags/include.ts
similarity index 100%
rename from test/unit/tags/include.ts
rename to test/unit/builtin/tags/include.ts
diff --git a/test/unit/tags/increment.ts b/test/unit/builtin/tags/increment.ts
similarity index 100%
rename from test/unit/tags/increment.ts
rename to test/unit/builtin/tags/increment.ts
diff --git a/test/unit/tags/layout.ts b/test/unit/builtin/tags/layout.ts
similarity index 100%
rename from test/unit/tags/layout.ts
rename to test/unit/builtin/tags/layout.ts
diff --git a/test/unit/tags/raw.ts b/test/unit/builtin/tags/raw.ts
similarity index 100%
rename from test/unit/tags/raw.ts
rename to test/unit/builtin/tags/raw.ts
diff --git a/test/unit/tags/tablerow.ts b/test/unit/builtin/tags/tablerow.ts
similarity index 100%
rename from test/unit/tags/tablerow.ts
rename to test/unit/builtin/tags/tablerow.ts
diff --git a/test/unit/tags/unless.ts b/test/unit/builtin/tags/unless.ts
similarity index 100%
rename from test/unit/tags/unless.ts
rename to test/unit/builtin/tags/unless.ts
diff --git a/test/unit/filters.ts b/test/unit/filters.ts
deleted file mode 100644
index daedd8cb5..000000000
--- a/test/unit/filters.ts
+++ /dev/null
@@ -1,425 +0,0 @@
-import { expect } from 'chai'
-import Liquid from '../../src/liquid'
-
-const ctx = {
-  date: new Date(),
-  foo: 'bar',
-  arr: [-2, 'a'],
-  obj: {
-    foo: 'bar'
-  },
-  func: function () {},
-  posts: [{
-    category: 'foo'
-  }, {
-    category: 'bar'
-  }]
-}
-let liquid
-
-async function test (src, dst) {
-  const html = await liquid.parseAndRender(src, ctx)
-  return expect(html).to.equal(dst)
-}
-
-describe('filters', function () {
-  before(() => { liquid = new Liquid() })
-  describe('abs', function () {
-    it('should return 3 for -3', () => test('{{ -3 | abs }}', '3'))
-    it('should return 2 for arr[0]', () => test('{{ arr[0] | abs }}', '2'))
-    it('should return convert string', () => test('{{ "-3" | abs }}', '3'))
-  })
-
-  describe('append', function () {
-    it('should return "-3abc" for -3, "abc"',
-      () => test('{{ -3 | append: "abc" }}', '-3abc'))
-    it('should return "abar" for "a",foo', () => test('{{ "a" | append: foo }}', 'abar'))
-  })
-
-  it('should support capitalize', () => test('{{ "i am good" | capitalize }}', 'I am good'))
-
-  describe('ceil', function () {
-    it('should return "2" for 1.2', () => test('{{ 1.2 | ceil }}', '2'))
-    it('should return "2" for 2.0', () => test('{{ 2.0 | ceil }}', '2'))
-    it('should return "4" for 3.5', () => test('{{ "3.5" | ceil }}', '4'))
-    it('should return "184" for 183.357', () => test('{{ 183.357 | ceil }}', '184'))
-  })
-
-  describe('concat', function () {
-    it('should concat arrays', () => test(`
-      {%- assign fruits = "apples, oranges, peaches" | split: ", " -%}
-      {%- assign vegetables = "carrots, turnips, potatoes" | split: ", " -%}
-
-      {%- assign everything = fruits | concat: vegetables -%}
-
-      {%- for item in everything -%}
-      - {{ item }}
-      {% endfor -%}`, `- apples
-      - oranges
-      - peaches
-      - carrots
-      - turnips
-      - potatoes
-      `))
-    it('should support chained concat', () => test(`
-      {%- assign fruits = "apples, oranges, peaches" | split: ", " -%}
-      {%- assign vegetables = "carrots, turnips, potatoes" | split: ", " -%}
-      {%- assign furniture = "chairs, tables, shelves" | split: ", " -%}
-      {%- assign everything = fruits | concat: vegetables | concat: furniture -%}
-
-      {%- for item in everything -%}
-      - {{ item }}
-      {% endfor -%}`, `- apples
-      - oranges
-      - peaches
-      - carrots
-      - turnips
-      - potatoes
-      - chairs
-      - tables
-      - shelves
-      `))
-  })
-
-  describe('date', function () {
-    it('should support date: %a %b %d %Y', function () {
-      const str = ctx.date.toDateString()
-      return test('{{ date | date:"%a %b %d %Y"}}', str)
-    })
-    it('should create a new Date when given "now"', function () {
-      return test('{{ "now" | date: "%Y"}}', (new Date()).getFullYear().toString())
-    })
-    it('should parse as Date when given UTC string', function () {
-      return test('{{ "1991-02-22T00:00:00" | date: "%Y"}}', '1991')
-    })
-    it('should render string as string if not valid', function () {
-      return test('{{ "foo" | date: "%Y"}}', 'foo')
-    })
-    it('should render object as string if not valid', function () {
-      return test('{{ obj | date: "%Y"}}', '{"foo":"bar"}')
-    })
-  })
-
-  describe('default', function () {
-    it('should use default when falsy', () => test('{{false |default: "a"}}', 'a'))
-    it('should not use default when truthy', () => test('{{true |default: "a"}}', 'true'))
-  })
-
-  describe('divided_by', function () {
-    it('should return 2 for 4,2', () => test('{{4 | divided_by: 2}}', '2'))
-    it('should return 4 for 16,4', () => test('{{16 | divided_by: 4}}', '4'))
-    it('should return 1 for 5,3', () => test('{{5 | divided_by: 3}}', (5 / 3).toString()))
-    it('should convert string to number', () => test('{{"6" | divided_by: "3"}}', '2'))
-  })
-
-  describe('downcase', function () {
-    it('should return "parker moore" for "Parker Moore"',
-      () => test('{{ "Parker Moore" | downcase }}', 'parker moore'))
-    it('should return "apple" for "apple"',
-      () => test('{{ "apple" | downcase }}', 'apple'))
-  })
-
-  describe('escape', function () {
-    it('should escape \' and &', function () {
-      return test('{{ "Have you read \'James & the Giant Peach\'?" | escape }}',
-        'Have you read &#39;James &amp; the Giant Peach&#39;?')
-    })
-    it('should escape normal string', function () {
-      return test('{{ "Tetsuro Takara" | escape }}', 'Tetsuro Takara')
-    })
-    it('should escape function', function () {
-      return test('{{ func | escape }}', 'function () { }')
-    })
-  })
-
-  describe('escape_once', function () {
-    it('should do escape', () =>
-      test('{{ "1 < 2 & 3" | escape_once }}', '1 &lt; 2 &amp; 3'))
-    it('should not escape twice',
-      () => test('{{ "1 &lt; 2 &amp; 3" | escape_once }}', '1 &lt; 2 &amp; 3'))
-  })
-
-  it('should support split/first', function () {
-    const src = '{% assign my_array = "apples, oranges, peaches, plums" | split: ", " %}' +
-      '{{ my_array | first }}'
-    return test(src, 'apples')
-  })
-
-  describe('floor', function () {
-    it('should return "1" for 1.2', () => test('{{ 1.2 | floor }}', '1'))
-    it('should return "2" for 2.0', () => test('{{ 2.0 | floor }}', '2'))
-    it('should return "183" for 183.357', () => test('{{ 183.357 | floor }}', '183'))
-    it('should return "3" for 3.5', () => test('{{ "3.5" | floor }}', '3'))
-  })
-
-  describe('join', function () {
-    it('should support join', function () {
-      const src = '{% assign beatles = "John, Paul, George, Ringo" | split: ", " %}' +
-        '{{ beatles | join: " and " }}'
-      return test(src, 'John and Paul and George and Ringo')
-    })
-    it('should default separator to space', function () {
-      const src = '{% assign beatles = "John, Paul, George, Ringo" | split: ", " %}' +
-        '{{ beatles | join }}'
-      return test(src, 'John Paul George Ringo')
-    })
-  })
-
-  it('should support split/last', function () {
-    const src = '{% assign my_array = "zebra, octopus, giraffe, tiger" | split: ", " %}' +
-      '{{ my_array|last }}'
-    return test(src, 'tiger')
-  })
-
-  it('should support lstrip', function () {
-    const src = '{{ "          So much room for activities!          " | lstrip }}'
-    return test(src, 'So much room for activities!          ')
-  })
-
-  it('should support map', function () {
-    return test('{{posts | map: "category"}}', '["foo","bar"]')
-  })
-
-  describe('minus', function () {
-    it('should return "2" for 4,2', () => test('{{ 4 | minus: 2 }}', '2'))
-    it('should return "12" for 16,4', () => test('{{ 16 | minus: 4 }}', '12'))
-    it('should return "171.357" for 183.357,12',
-      () => test('{{ 183.357 | minus: 12 }}', '171.357'))
-    it('should convert first arg as number', () => test('{{ "4" | minus: 1 }}', '3'))
-    it('should convert both args as number', () => test('{{ "4" | minus: "1" }}', '3'))
-  })
-
-  describe('modulo', function () {
-    it('should return "1" for 3,2', () => test('{{ 3 | modulo: 2 }}', '1'))
-    it('should return "3" for 24,7', () => test('{{ 24 | modulo: 7 }}', '3'))
-    it('should return "3.357" for 183.357,12',
-      () => test('{{ 183.357 | modulo: 12 }}', '3.357'))
-    it('should convert string', () => test('{{ "24" | modulo: "7" }}', '3'))
-  })
-
-  it('should support string_with_newlines', function () {
-    const src = '{% capture string_with_newlines %}\n' +
-            'Hello\n' +
-            'there\n' +
-            '{% endcapture %}' +
-            '{{ string_with_newlines | newline_to_br }}'
-    const dst = '<br />' +
-            'Hello<br />' +
-            'there<br />'
-    return test(src, dst)
-  })
-
-  describe('plus', function () {
-    it('should return "6" for 4,2', () => test('{{ 4 | plus: 2 }}', '6'))
-    it('should return "20" for 16,4', () => test('{{ 16 | plus: 4 }}', '20'))
-    it('should return "195.357" for 183.357,12',
-      () => test('{{ 183.357 | plus: 12 }}', '195.357'))
-    it('should convert first arg as number', () => test('{{ "4" | plus: 2 }}', '6'))
-    it('should convert both args as number', () => test('{{ "4" | plus: "2" }}', '6'))
-  })
-
-  it('should support prepend', function () {
-    return test('{% assign url = "liquidmarkup.com" %}' +
-            '{{ "/index.html" | prepend: url }}',
-    'liquidmarkup.com/index.html')
-  })
-
-  it('should support remove', function () {
-    return test('{{ "I strained to see the train through the rain" | remove: "rain" }}',
-      'I sted to see the t through the ')
-  })
-
-  it('should support remove_first', function () {
-    return test('{{ "I strained to see the train through the rain" | remove_first: "rain" }}',
-      'I sted to see the train through the rain')
-  })
-
-  it('should support replace', function () {
-    return test('{{ "Take my protein pills and put my helmet on" | replace: "my", "your" }}',
-      'Take your protein pills and put your helmet on')
-  })
-
-  it('should support replace_first', function () {
-    return test('{% assign my_string = "Take my protein pills and put my helmet on" %}\n' +
-            '{{ my_string | replace_first: "my", "your" }}',
-    '\nTake your protein pills and put my helmet on')
-  })
-
-  it('should support reverse', function () {
-    return test('{{ "Ground control to Major Tom." | split: "" | reverse | join: "" }}',
-      '.moT rojaM ot lortnoc dnuorG')
-  })
-
-  describe('round', function () {
-    it('should return "1" for 1.2', () => test('{{1.2|round}}', '1'))
-    it('should return "3" for 2.7', () => test('{{2.7|round}}', '3'))
-    it('should return "183.36" for 183.357,2',
-      () => test('{{183.357|round: 2}}', '183.36'))
-    it('should convert string to number', () => test('{{"2.7"|round}}', '3'))
-  })
-
-  it('should support rstrip', function () {
-    return test('{{ "          So much room for activities!          " | rstrip }}',
-      '          So much room for activities!')
-  })
-
-  describe('size', function () {
-    it('should return string length',
-      () => test('{{ "Ground control to Major Tom." | size }}', '28'))
-    it('should return array size', function () {
-      return test('{% assign my_array = "apples, oranges, peaches, plums"' +
-                ' | split: ", " %}{{ my_array | size }}',
-      '4')
-    })
-    it('should also be used with dot notation - string',
-      () => test('{% assign my_string = "Ground control to Major Tom." %}{{ my_string.size }}', '28'))
-    it('should also be used with dot notation - array',
-      () => test('{% assign my_array = "apples, oranges, peaches, plums" | split: ", " %}{{ my_array.size }}', '4'))
-  })
-
-  describe('slice', function () {
-    it('should slice first char by 0', () => test('{{ "Liquid" | slice: 0 }}', 'L'))
-    it('should slice third char by 2', () => test('{{ "Liquid" | slice: 2 }}', 'q'))
-    it('should slice substr by 2,5', () => test('{{ "Liquid" | slice: 2, 5 }}', 'quid'))
-    it('should slice substr by -3,2', () => test('{{ "Liquid" | slice: -3, 2 }}', 'ui'))
-    it('should support array', () => test('{{ "1,2,3,4" | split: "," | slice: 1,2 | join }}', '2 3'))
-  })
-
-  it('should support sort', function () {
-    return test('{% assign my_array = "zebra, octopus, giraffe, Sally Snake"' +
-            ' | split: ", " %}' +
-            '{{ my_array | sort | join: ", " }}',
-    'Sally Snake, giraffe, octopus, zebra')
-  })
-
-  it('should support split', function () {
-    return test('{% assign beatles = "John, Paul, George, Ringo" | split: ", " %}' +
-            '{% for member in beatles %}' +
-            '{{ member }} ' +
-            '{% endfor %}',
-    'John Paul George Ringo ')
-  })
-
-  it('should support strip', function () {
-    return test('{{ "          So much room for activities!          " | strip }}',
-      'So much room for activities!')
-  })
-
-  describe('strip_html', function () {
-    it('should strip all tags', function () {
-      return test('{{ "Have <em>you</em> read <cite><a href=&quot;https://en.wikipedia.org/wiki/Ulysses_(novel)&quot;>Ulysses</a></cite>?" | strip_html }}',
-        'Have you read Ulysses?')
-    })
-    it('should strip all comment tags', function () {
-      return test('{{ "<!--Have you read-->Ulysses?" | strip_html }}',
-        'Ulysses?')
-    })
-    it('should strip all style tags and their contents', function () {
-      return test('{{ "<style>cite { font-style: italic; }</style><cite>Ulysses<cite>?" | strip_html }}',
-        'Ulysses?')
-    })
-    it('should strip all scripts tags and their contents', function () {
-      return test('{{ "<script async>console.log(\'hello world\')</script><cite>Ulysses<cite>?" | strip_html }}',
-        'Ulysses?')
-    })
-    it('should strip until empty', function () {
-      return test('{{"<br/><br />< p ></p></ p >" | strip_html }}', '')
-    })
-  })
-
-  it('should support strip_newlines', function () {
-    return test('{% capture string_with_newlines %}\n' +
-            'Hello\nthere\n{% endcapture %}' +
-            '{{ string_with_newlines | strip_newlines }}',
-    'Hellothere')
-  })
-
-  describe('times', function () {
-    it('should return "6" for 3,2', () => test('{{ 3 | times: 2 }}', '6'))
-    it('should return "168" for 24,7', () => test('{{ 24 | times: 7 }}', '168'))
-    it('should return "2200.284" for 183.357,12',
-      () => test('{{ 183.357 | times: 12 }}', '2200.284'))
-    it('should convert string to number', () => test('{{ "24" | times: "7" }}', '168'))
-  })
-
-  describe('truncate', function () {
-    it('should truncate when string too long', function () {
-      return test('{{ "Ground control to Major Tom." | truncate: 20 }}',
-        'Ground control to...')
-    })
-    it('should not truncate when string not long enough', function () {
-      return test('{{ "Ground control to Major Tom." | truncate: 80 }}',
-        'Ground control to Major Tom.')
-    })
-    it('should truncate with custom ellipsis', function () {
-      return test('{{ "Ground control to Major Tom." | truncate: 25,", and so on" }}',
-        'Ground control, and so on')
-    })
-    it('should truncate with empty custom ellipsis', function () {
-      return test('{{ "Ground control to Major Tom." | truncate: 20, "" }}',
-        'Ground control to Ma')
-    })
-    it('should not truncate when short enough', function () {
-      return test('{{ "12345" | truncate: 5 }}', '12345')
-    })
-    it('should default to 16', function () {
-      return test('{{ "1234567890abcdefghi" | truncate }}', '1234567890abc...')
-    })
-  })
-
-  describe('truncatewords', function () {
-    it('should truncate when too many words', function () {
-      return test('{{ "Ground control to Major Tom." | truncatewords: 3 }}',
-        'Ground control to...')
-    })
-    it('should not truncate when not enough words', function () {
-      return test('{{ "Ground control to Major Tom." | truncatewords: 8 }}',
-        'Ground control to Major Tom.')
-    })
-    it('should truncate with custom ellipsis', function () {
-      return test('{{ "Ground control to Major Tom." | truncatewords: 3, "--" }}',
-        'Ground control to--')
-    })
-    it('should truncate with empty custom ellipsis', function () {
-      return test('{{ "Ground control to Major Tom." | truncatewords: 3, "" }}',
-        'Ground control to')
-    })
-  })
-
-  describe('uniq', function () {
-    it('should uniq string list', function () {
-      return test(
-        '{% assign my_array = "ants, bugs, bees, bugs, ants" | split: ", " %}' +
-        '{{ my_array | uniq | join: ", " }}',
-        'ants, bugs, bees'
-      )
-    })
-    it('should uniq falsy value', function () {
-      return test('{{"" | uniq | join: ","}}', '')
-    })
-  })
-
-  it('should support upcase', () => test('{{ "Parker Moore" | upcase }}', 'PARKER MOORE'))
-
-  describe('url_decode', function () {
-    it('should decode %xx and +',
-      () => test('{{ "%27Stop%21%27+said+Fred" | url_decode }}', "'Stop!' said Fred"))
-  })
-
-  describe('url_encode', function () {
-    it('should encode @',
-      () => test('{{ "john@liquid.com" | url_encode }}', 'john%40liquid.com'))
-    it('should encode <space>',
-      () => test('{{ "Tetsuro Takara" | url_encode }}', 'Tetsuro+Takara'))
-  })
-
-  describe('obj_test', function () {
-    before(() => {
-      liquid.registerFilter('obj_test', function () {
-        return Array.prototype.slice.call(arguments).join(',')
-      })
-    })
-    it('should support object', () => test(`{{ "a" | obj_test: k1: "v1", k2: foo }}`, 'a,k1,v1,k2,bar'))
-    it('should support mixed object', () => test(`{{ "a" | obj_test: "something", k1: "v1", k2: foo }}`, 'a,something,k1,v1,k2,bar'))
-  })
-})
diff --git a/test/unit/fs/browser.ts b/test/unit/fs/browser.ts
new file mode 100644
index 000000000..3dd4a8de4
--- /dev/null
+++ b/test/unit/fs/browser.ts
@@ -0,0 +1,84 @@
+import fs from 'src/fs/browser'
+import * as sinon from 'sinon'
+import { expect, use } from 'chai'
+import * as chaiAsPromised from 'chai-as-promised'
+
+use(chaiAsPromised)
+const resolve = fs.resolve
+
+describe('fs/browser', function () {
+  describe('#resolve()', function () {
+    if (+process.version.match(/^v(\d+)/)[1] < 8) {
+      console.info('jsdom not supported, skipping template-browser...')
+      return
+    }
+    const JSDOM = require('jsdom').JSDOM
+    beforeEach(function () {
+      const dom = new JSDOM(``, {
+        url: 'https://example.com/foo/bar/',
+        contentType: 'text/html',
+        includeNodeLocations: true
+      });
+      (global as any).document = dom.window.document
+    })
+    afterEach(function () {
+      delete (global as any).document
+    })
+    it('should support relative root', function () {
+      expect(resolve('./views/', 'foo', '')).to.equal('https://example.com/foo/bar/views/foo')
+    })
+    it('should treat root as directory', function () {
+      expect(resolve('./views', 'foo', '')).to.equal('https://example.com/foo/bar/views/foo')
+    })
+    it('should support absolute root', function () {
+      expect(resolve('/views', 'foo', '')).to.equal('https://example.com/views/foo')
+    })
+    it('should support empty root', function () {
+      expect(resolve('', 'page.html', '')).to.equal('https://example.com/foo/bar/page.html')
+    })
+    it('should support full url as root', function () {
+      expect(resolve('https://example.com/views/', 'page.html', '')).to.equal('https://example.com/views/page.html')
+    })
+    it('should add extname when absent', function () {
+      expect(resolve('https://example.com/views/', 'page', '.html')).to.equal('https://example.com/views/page.html')
+    })
+    it('should add extname for urls have searchParams', function () {
+      expect(resolve('https://example.com/views/', 'page?foo=bar', '.html')).to.equal('https://example.com/views/page.html?foo=bar')
+    })
+    it('should not add extname when full url is given', function () {
+      expect(resolve('https://example.com/views/', 'https://google.com/page.php', '.html')).to.equal('https://google.com/page.php')
+    })
+    it('should not add extname when already have one', function () {
+      expect(resolve('https://example.com/views/', 'page.php', '.html')).to.equal('https://example.com/views/page.php')
+    })
+  })
+
+  describe('#readFile()', () => {
+    let server
+    beforeEach(() => {
+      server = sinon.createFakeServer()
+      server.autoRespond = true
+      server.respondWith('GET', 'https://example.com/views/hello.html',
+        [200, { 'Content-Type': 'text/plain' }, 'hello {{name}}']);
+      (global as any).XMLHttpRequest = sinon.useFakeXMLHttpRequest()
+    })
+    afterEach(() => {
+      server.restore()
+      delete (global as any).XMLHttpRequest
+    })
+    it('should get corresponding text', async function () {
+      const html = await fs.readFile('https://example.com/views/hello.html')
+      return expect(html).to.equal('hello {{name}}')
+    })
+    it('should throw 404', () => {
+      return expect(fs.readFile('https://example.com/not/exist.html'))
+        .to.be.rejectedWith('Not Found')
+    })
+    it('should throw error', function () {
+      const result = expect(fs.readFile('https://example.com/views/hello.html'))
+        .to.be.rejectedWith('An error occurred whilst receiving the response.')
+      server.requests[0].error()
+      return result
+    })
+  })
+})
diff --git a/test/unit/fs/node.ts b/test/unit/fs/node.ts
new file mode 100644
index 000000000..c7ec20212
--- /dev/null
+++ b/test/unit/fs/node.ts
@@ -0,0 +1,47 @@
+import fs from 'src/fs/node'
+import * as path from 'path'
+import { expect, use } from 'chai'
+import * as chaiAsPromised from 'chai-as-promised'
+import { mock, restore } from 'test/stub/mockfs'
+
+use(chaiAsPromised)
+
+describe('fs', function () {
+  before(() => mock({
+    '/foo/bar.html': 'bar',
+    '/un-readable.html': { mode: '0000', content: '' }
+  }))
+  after(restore)
+
+  describe('#resolve()', function () {
+    it('should resolve based on root', async function () {
+      const filepath = fs.resolve('/foo', 'bar.html', '.liquid')
+      const expected = path.resolve('/foo/bar.html')
+      return expect(filepath).to.equal(expected)
+    })
+    it('should add extension if it has no extension', async function () {
+      const filepath = fs.resolve('/foo', 'bar', '.liquid')
+      const expected = path.resolve('/foo/bar.liquid')
+      return expect(filepath).to.equal(expected)
+    })
+  })
+  describe('#exists', () => {
+    it('should resolve as false if not exists', async () => {
+      const result = await fs.exists('/foo/foo.html')
+      return expect(result).to.be.false
+    })
+    it('should resolve as true if exists', async () => {
+      const result = await fs.exists('/foo/bar.html')
+      return expect(result).to.be.true
+    })
+  })
+  describe('#readFile', function () {
+    it('should throw when not exist', function () {
+      return expect(fs.readFile('/foo/foo.html')).to.rejectedWith('ENOENT')
+    })
+    it('should throw when file not readable', function () {
+      return expect(fs.readFile('/un-readable.html')).to
+        .be.rejectedWith(/EACCES/)
+    })
+  })
+})
diff --git a/test/unit/options/cache.ts b/test/unit/liquid/cache.ts
similarity index 100%
rename from test/unit/options/cache.ts
rename to test/unit/liquid/cache.ts
diff --git a/test/unit/liquid.ts b/test/unit/liquid/liquid.ts
similarity index 87%
rename from test/unit/liquid.ts
rename to test/unit/liquid/liquid.ts
index a12014b57..6535fc3d8 100644
--- a/test/unit/liquid.ts
+++ b/test/unit/liquid/liquid.ts
@@ -1,15 +1,10 @@
-import Liquid from '../../src/liquid'
+import Liquid from 'src/liquid'
 import * as chai from 'chai'
 import { mock, restore } from 'test/stub/mockfs'
 
 const expect = chai.expect
 
 describe('Liquid', function () {
-  describe('#constructor()', function () {
-    it('should throw on illegal root', function () {
-      expect(() => new (Liquid as any)({ root: {} })).to.throw(/illegal root/)
-    })
-  })
   describe('#plugin()', function () {
     it('should call plugin on the instance', async function () {
       const engine = new Liquid()
diff --git a/test/unit/options/strict.ts b/test/unit/liquid/strict.ts
similarity index 100%
rename from test/unit/options/strict.ts
rename to test/unit/liquid/strict.ts
diff --git a/test/unit/options/trimming.ts b/test/unit/liquid/trimming.ts
similarity index 98%
rename from test/unit/options/trimming.ts
rename to test/unit/liquid/trimming.ts
index 63666c4be..55e6d5043 100644
--- a/test/unit/options/trimming.ts
+++ b/test/unit/liquid/trimming.ts
@@ -1,5 +1,5 @@
 import { expect } from 'chai'
-import Liquid from '../../../src/liquid'
+import Liquid from 'src/liquid'
 
 describe('LiquidOptions#trimming', function () {
   const ctx = { name: 'harttle' }
diff --git a/test/unit/lexical.ts b/test/unit/parser/lexical.ts
similarity index 98%
rename from test/unit/lexical.ts
rename to test/unit/parser/lexical.ts
index 67d7d1736..bfb0bb325 100644
--- a/test/unit/lexical.ts
+++ b/test/unit/parser/lexical.ts
@@ -1,7 +1,7 @@
 import * as chai from 'chai'
 
 const expect = chai.expect
-const lexical = require('../../src/parser/lexical')
+const lexical = require('src/parser/lexical')
 
 describe('lexical', function () {
   it('should test filter syntax', function () {
diff --git a/test/unit/tokenizer.ts b/test/unit/parser/tokenizer.ts
similarity index 100%
rename from test/unit/tokenizer.ts
rename to test/unit/parser/tokenizer.ts
diff --git a/test/unit/render.ts b/test/unit/render/render.ts
similarity index 85%
rename from test/unit/render.ts
rename to test/unit/render/render.ts
index f80345cea..8d66f3b91 100644
--- a/test/unit/render.ts
+++ b/test/unit/render/render.ts
@@ -1,9 +1,9 @@
 import { expect } from 'chai'
-import Scope from '../../src/scope/scope'
-import Token from '../../src/parser/token'
+import Scope from 'src/scope/scope'
+import Token from 'src/parser/token'
 import Tag from 'src/template/tag/tag'
 import Filter from 'src/template/filter'
-import Render from '../../src/render/render'
+import Render from 'src/render/render'
 import HTML from 'src/template/html'
 
 describe('render', function () {
diff --git a/test/unit/syntax.ts b/test/unit/render/syntax.ts
similarity index 100%
rename from test/unit/syntax.ts
rename to test/unit/render/syntax.ts
diff --git a/test/unit/scope.ts b/test/unit/scope/scope.ts
similarity index 100%
rename from test/unit/scope.ts
rename to test/unit/scope/scope.ts
diff --git a/test/unit/template-browser.ts b/test/unit/template-browser.ts
deleted file mode 100644
index 8989c3d02..000000000
--- a/test/unit/template-browser.ts
+++ /dev/null
@@ -1,83 +0,0 @@
-import { resolve } from '../../src/parser/template-browser'
-import { expect } from 'chai'
-
-describe('template-browser', function () {
-  if (+process.version.match(/^v(\d+)/)[1] < 8) {
-    console.info('jsdom not supported, skipping template-browser...')
-    return
-  }
-  const JSDOM = require('jsdom').JSDOM
-  beforeEach(function () {
-    const dom = new JSDOM(``, {
-      url: 'https://example.com/foo/bar/',
-      contentType: 'text/html',
-      includeNodeLocations: true
-    });
-    (global as any).document = dom.window.document
-  })
-  afterEach(function () {
-    delete (global as any).document
-  })
-  describe('resolve', function () {
-    it('should support relative root', function () {
-      expect(resolve('foo', './views/', {
-        extname: '',
-        root: ['.']
-      })).to.equal('https://example.com/foo/bar/views/foo')
-    })
-    it('should treat root as directory', function () {
-      expect(resolve('foo', './views', {
-        extname: '',
-        root: ['.']
-      })).to.equal('https://example.com/foo/bar/views/foo')
-    })
-    it('should support absolute root', function () {
-      expect(resolve('foo', '/views', {
-        extname: '',
-        root: ['.']
-      })).to.equal('https://example.com/views/foo')
-    })
-    it('should support empty root', function () {
-      expect(resolve('page.html', '', {
-        extname: '',
-        root: ['.']
-      })).to.equal('https://example.com/foo/bar/page.html')
-    })
-    it('should support full url as root', function () {
-      expect(resolve('page.html', 'https://example.com/views/', {
-        extname: '',
-        root: ['.']
-      })).to.equal('https://example.com/views/page.html')
-    })
-    it('should use options.root when root argument absent', function () {
-      expect(resolve('page.html', null, {
-        extname: '',
-        root: ['https://example.com/views', 'https://google.com/views']
-      })).to.equal('https://example.com/views/page.html')
-    })
-    it('should add extname when absent', function () {
-      expect(resolve('page', 'https://example.com/views/', {
-        extname: '.html',
-        root: ['.']
-      })).to.equal('https://example.com/views/page.html')
-    })
-    it('should add extname for urls have searchParams', function () {
-      expect(resolve('page?foo=bar', 'https://example.com/views/', {
-        extname: '.html',
-        root: ['.']
-      })).to.equal('https://example.com/views/page.html?foo=bar')
-    })
-    it('should not add extname when full url is given', function () {
-      expect(resolve('https://google.com/page.php', 'https://example.com/views/', {
-        extname: '.html',
-        root: ['.']
-      })).to.equal('https://google.com/page.php')
-    })
-    it('should not add extname when already have one', function () {
-      expect(resolve('page.php', 'https://example.com/views/', {
-        extname: '.html',
-        root: ['.']
-      })).to.equal('https://example.com/views/page.php')
-    })
-  })
-})
diff --git a/test/unit/template.ts b/test/unit/template.ts
deleted file mode 100644
index d23102e7b..000000000
--- a/test/unit/template.ts
+++ /dev/null
@@ -1,24 +0,0 @@
-import { resolve } from '../../src/parser/template'
-import * as path from 'path'
-import { expect, use } from 'chai'
-import * as chaiAsPromised from 'chai-as-promised'
-import { mock, restore } from '../stub/mockfs'
-
-use(chaiAsPromised)
-
-describe('template', function () {
-  before(() => mock({ '/foo/bar.html': 'bar' }))
-  after(restore)
-
-  describe('#resolve()', function () {
-    it('should resolve based on root', async function () {
-      const filepath = await resolve('bar.html', '/foo', { root: [] })
-      const expected = path.resolve('/foo/bar.html')
-      return expect(filepath).to.equal(expected)
-    })
-    it('should resolve based on root', function () {
-      return expect(resolve('foo.html', '/foo', { root: [] }))
-        .to.rejectedWith(/Failed to lookup foo.html in: \/foo/)
-    })
-  })
-})
diff --git a/test/unit/filter.ts b/test/unit/template/filter.ts
similarity index 100%
rename from test/unit/filter.ts
rename to test/unit/template/filter.ts
diff --git a/test/unit/output.ts b/test/unit/template/output.ts
similarity index 96%
rename from test/unit/output.ts
rename to test/unit/template/output.ts
index 0d970af41..6a1cd3874 100644
--- a/test/unit/output.ts
+++ b/test/unit/template/output.ts
@@ -1,6 +1,6 @@
 import * as chai from 'chai'
-import Scope from '../../src/scope/scope'
-import Output from '../../src/template/output'
+import Scope from 'src/scope/scope'
+import Output from 'src/template/output'
 import OutputToken from 'src/parser/output-token'
 import Filter from 'src/template/filter'
 
diff --git a/test/unit/tag.ts b/test/unit/template/tag.ts
similarity index 100%
rename from test/unit/tag.ts
rename to test/unit/template/tag.ts
diff --git a/test/unit/value.ts b/test/unit/template/value.ts
similarity index 98%
rename from test/unit/value.ts
rename to test/unit/template/value.ts
index 2941081dc..bfa46d5f6 100644
--- a/test/unit/value.ts
+++ b/test/unit/template/value.ts
@@ -1,7 +1,7 @@
 import * as chai from 'chai'
 import * as sinonChai from 'sinon-chai'
 import * as sinon from 'sinon'
-import Scope from '../../src/scope/scope'
+import Scope from 'src/scope/scope'
 import Filter from 'src/template/filter'
 import Value from 'src/template/value'
 
diff --git a/test/unit/util/assert.ts b/test/unit/util/assert.ts
index 046b06ed5..acf94ff4e 100644
--- a/test/unit/util/assert.ts
+++ b/test/unit/util/assert.ts
@@ -1,5 +1,5 @@
 import * as chai from 'chai'
-import assert from '../../../src/util/assert'
+import assert from 'src/util/assert'
 
 const expect = chai.expect
 
diff --git a/test/unit/util/promise.ts b/test/unit/util/promise.ts
index 8747abb69..661e02e18 100644
--- a/test/unit/util/promise.ts
+++ b/test/unit/util/promise.ts
@@ -5,7 +5,7 @@ import * as sinonChai from 'sinon-chai'
 const expect = chai.expect
 chai.use(sinonChai)
 
-const P = require('../../../src/util/promise')
+const P = require('src/util/promise')
 
 describe('util/promise', function () {
   describe('.anySeries()', function () {
diff --git a/test/unit/util/strftime.ts b/test/unit/util/strftime.ts
index 035f47e17..16ccbd1e4 100644
--- a/test/unit/util/strftime.ts
+++ b/test/unit/util/strftime.ts
@@ -1,5 +1,5 @@
 import * as chai from 'chai'
-import t from '../../../src/util/strftime'
+import t from 'src/util/strftime'
 
 const expect = chai.expect
 
diff --git a/test/unit/util/underscore.ts b/test/unit/util/underscore.ts
index 1e0076d85..f03540dbf 100644
--- a/test/unit/util/underscore.ts
+++ b/test/unit/util/underscore.ts
@@ -1,8 +1,8 @@
 import * as chai from 'chai'
 import * as sinonChai from 'sinon-chai'
 import * as sinon from 'sinon'
-import { RenderError, RenderBreakError } from '../../../src/util/error'
-import * as _ from '../../../src/util/underscore'
+import { RenderError, RenderBreakError } from 'src/util/error'
+import * as _ from 'src/util/underscore'
 
 const expect = chai.expect
 chai.use(sinonChai)
diff --git a/test/unit/xhr.ts b/test/unit/xhr.ts
deleted file mode 100644
index 94bdc6d77..000000000
--- a/test/unit/xhr.ts
+++ /dev/null
@@ -1,44 +0,0 @@
-import { read } from 'src/parser/template-browser'
-import * as sinon from 'sinon'
-import { expect, use } from 'chai'
-import * as chaiAsPromised from 'chai-as-promised'
-
-use(chaiAsPromised)
-
-describe('xhr', () => {
-  if (+process.version.match(/^v(\d+)/)[1] < 8) {
-    console.info('jsdom not supported, skipping xhr...')
-    return
-  }
-  let server
-  beforeEach(() => {
-    server = sinon.createFakeServer()
-    server.autoRespond = true
-    server.respondWith('GET', 'https://example.com/views/hello.html',
-      [200, { 'Content-Type': 'text/plain' }, 'hello {{name}}']);
-    (global as any).XMLHttpRequest = sinon.useFakeXMLHttpRequest()
-  })
-  afterEach(() => {
-    server.restore()
-    delete (global as any).XMLHttpRequest
-  })
-  describe('#read()', () => {
-    it('should get corresponding text', async function () {
-      const html = await read('https://example.com/views/hello.html')
-      return expect(html).to.equal('hello {{name}}')
-    })
-    it('should throw 404', () => {
-      return expect(read('https://example.com/not/exist.html'))
-        .to.be.rejectedWith('Not Found')
-    })
-    it('should throw error', function (done) {
-      read('https://example.com/views/hello.html')
-        .then(() => done('should not be resolved'))
-        .catch(function (e) {
-          expect(e.message).to.equal('An error occurred whilst receiving the response.')
-          done()
-        })
-      server.requests[0].error()
-    })
-  })
-})
diff --git a/tsconfig.json b/tsconfig.json
index c8317eb48..7cc23e7ae 100644
--- a/tsconfig.json
+++ b/tsconfig.json
@@ -10,7 +10,7 @@
     "emitDecoratorMetadata": true,
     "baseUrl": ".",
     "paths": {
-      "template": ["src/parser/template"],
+      "src/fs": ["src/fs/node"],
       "src/*": ["src/*"],
       "test/*": ["test/*"]
     }