perf: add cross-engines benchmark

.mocharc.js

@@ -0,0 +1,4 @@
+module.exports = {
+  require: "ts-node/register/transpile-only",
+  reporter: "spec"
+}

benchmark/cross-engines.js

@@ -0,0 +1,31 @@
+#!/usr/bin/env node
+
+const Benchmark = require('benchmark')
+const data = require('./data/todolist.json')
+const path = require('path')
+
+const engines = {
+  liquid: require('./engines/liquid'),
+  handlebars: require('./engines/handlebars'),
+  react: require('./engines/react'),
+  swig: require('./engines/swig')
+}
+
+function crossEngines () {
+  console.log('     cross engines')
+  console.log('------------------------')
+  return new Promise(resolve => {
+    const suit = new Benchmark.Suite('cross engines')
+
+    for (const [name, { load, render }] of Object.entries(engines)) {
+      const tpl = load(path.resolve(__dirname, `templates/todolist`))
+      suit.add(name, () => render(tpl, data))
+    }
+
+    suit.on('cycle', event => console.log(String(event.target)))
+    suit.on('complete', resolve)
+    suit.run({ async: true })
+  })
+}
+
+module.exports = { crossEngines }

benchmark/data/todolist.json

@@ -0,0 +1,29 @@
+
+{
+  "categories": [{
+    "color": "red",
+    "id": "CAT1",
+    "title": "work"
+  }, {
+    "color": "red",
+    "id": "CAT2",
+    "title": "emergency"
+  }, {
+    "color": "green",
+    "id": "CAT3",
+    "title": "sport"
+  }],
+  "todos": [{
+    "title": "fork and clone",
+    "id": "TODO1",
+    "category": "work"
+  }, {
+    "title": "make it better",
+    "id": "TODO2",
+    "category": "sport"
+  }, {
+    "title": "make a pull request",
+    "id": "TODO3",
+    "category": "work"
+  }]
+}

benchmark/demo.js

@@ -1,8 +1,10 @@
 const Benchmark = require('benchmark')
 const { Liquid } = require('..')
+const ctx = require('./data/todolist.json')
+const { resolve } = require('path')
 
 const engine = new Liquid({
-  root: __dirname,
+  root: resolve(__dirname, 'templates'),
   extname: '.liquid'
 })
 
@@ -17,28 +19,14 @@ engine.registerTag('header', {
   }
 })
 
-const ctx = {
-  todos: ['fork and clone', 'make it better', 'make a pull request'],
-  title: 'Welcome to liquidjs!'
-}
-
-const template = `
-{%header content: "welcome to liquid" | capitalize%}
-
-<ul>
-  {% for todo in todos %}
-  <li>{{forloop.index}} - {{todo}}</li>
-  {% endfor %}
-</ul>
-`
-
 function demo () {
-  console.log('--- demo ---')
+  console.log('         demo')
+  console.log('------------------------')
   return new Promise(resolve => {
     new Benchmark.Suite('demo')
       .add('demo', {
         defer: true,
-        fn: d => engine.parseAndRender(template, ctx).then(x => d.resolve(x))
+        fn: d => engine.renderFile('todolist', ctx).then(x => d.resolve(x))
       })
       .on('cycle', event => console.log(String(event.target)))
       .on('complete', resolve)

benchmark/engines/handlebars.js

@@ -0,0 +1,33 @@
+const handlebars = require('handlebars')
+const { readFileSync } = require('fs')
+const { join } = require('path')
+
+handlebars.registerPartial(
+  'todo-icon',
+  readFileSync(join(__dirname, '../templates/todo-icon.hbs'), 'utf8')
+)
+
+handlebars.registerHelper('concat', function (...args) {
+  return args.filter(x => typeof x === 'string').join('')
+})
+
+handlebars.registerHelper('url', function (path) {
+  return `http://example.com${path}`
+})
+
+handlebars.registerHelper('inc', function (num) {
+  return Number(num) + 1
+})
+
+handlebars.registerHelper('capitalize', function (str) {
+  return str[0].toUpperCase() + str.slice(1).toLowerCase()
+})
+
+handlebars.registerHelper('upcase', function (str) {
+  return str.toUpperCase()
+})
+
+module.exports = {
+  load: path => handlebars.compile(readFileSync(path + '.hbs', 'utf8')),
+  render: (tpl, data) => tpl(data)
+}

benchmark/engines/liquid.js

@@ -0,0 +1,15 @@
+const { Liquid } = require('../..')
+const { readFileSync } = require('fs')
+const { join } = require('path')
+
+const liquid = new Liquid({
+  root: join(__dirname, '../templates'),
+  extname: '.liquid'
+})
+
+liquid.registerFilter('url', path => `http://example.com${path}`)
+
+module.exports = {
+  load: path => liquid.parse(readFileSync(path + '.liquid', 'utf8')),
+  render: (tpl, data) => liquid.renderSync(tpl, data)
+}

benchmark/engines/react.js

@@ -0,0 +1,20 @@
+const { readFileSync } = require('fs')
+const React = require('react')
+const ReactDOMServer = require('react-dom/server')
+const babel = require('@babel/core')
+const requireFromString = require('require-from-string')
+
+const babelConfig = {
+  presets: ['@babel/preset-react', '@babel/preset-env']
+}
+
+module.exports = {
+  load: path => {
+    const src = readFileSync(path + '.jsx', 'utf8')
+    const transformed = babel.transform(src, babelConfig)
+    return requireFromString(transformed.code)
+  },
+  render: (Component, data) => {
+    return ReactDOMServer.renderToString(React.createElement(Component, data))
+  }
+}

benchmark/engines/swig.js

@@ -0,0 +1,30 @@
+const swig = require('swig')
+
+swig.setFilter('url', function (path) {
+  return `http://example.com${path}`
+})
+
+swig.setFilter('prepend', function (input, arg) {
+  return arg + input
+})
+
+swig.setFilter('append', function (input, arg) {
+  return input + arg
+})
+
+swig.setFilter('inc', function (num) {
+  return Number(num) + 1
+})
+
+swig.setFilter('capitalize', function (str) {
+  return str[0].toUpperCase() + str.slice(1).toLowerCase()
+})
+
+swig.setFilter('upcase', function (str) {
+  return str.toUpperCase()
+})
+
+module.exports = {
+  load: path => swig.compileFile(path + '.swig'),
+  render: (tpl, data) => tpl(data)
+}

benchmark/index.js

@@ -3,6 +3,7 @@ const { tag } = require('./tag')
 const { demo } = require('./demo')
 const { layout } = require('./layout')
 const { memory } = require('./memory')
+const { crossEngines } = require('./cross-engines')
 
 async function main () {
   await output()
@@ -10,6 +11,7 @@ async function main () {
   await demo()
   await layout()
   await memory()
+  await crossEngines()
 }
 
 main()

benchmark/layout.js

@@ -18,7 +18,8 @@ const template = `
 `
 
 function layout () {
-  console.log('--- layout ---')
+  console.log('         layout')
+  console.log('------------------------')
   return new Promise(resolve => {
     new Benchmark.Suite('layout')
       .add('cache=false', {

benchmark/memory.js

@@ -13,7 +13,8 @@ const engine = new Liquid(engineOptions)
 const SAMPLE_COUNT = 1024
 
 function memory () {
-  console.log('--- memory ---')
+  console.log('         memory')
+  console.log('------------------------')
   html()
   todolist()
 }
@@ -29,11 +30,11 @@ function html () {
     templates.push(engine.parse(str))
   }
   const diff1 = (getHeapStatistics().used_heap_size - base) / SAMPLE_COUNT
-  console.log(`${h(str.length)} lorem-html before GC x ${h(diff1)}/tpl (${SAMPLE_COUNT} instances sampled)`)
+  console.log(`[lorem-html ${h(str.length)}][before GC] ${h(diff1)}/tpl (${SAMPLE_COUNT} runs sampled)`)
 
   global.gc()
   const diff2 = (getHeapStatistics().used_heap_size - base) / SAMPLE_COUNT
-  console.log(`${h(str.length)} lorem-html after GC x ${h(diff2)}/tpl (${SAMPLE_COUNT} instances sampled)`)
+  console.log(`[lorem-html ${h(str.length)}][after GC] ${h(diff2)}/tpl (${SAMPLE_COUNT} runs sampled)`)
 }
 
 function todolist () {
@@ -47,15 +48,15 @@ function todolist () {
     templates.push(engine.parse(str))
   }
   const diff1 = (getHeapStatistics().used_heap_size - base) / SAMPLE_COUNT
-  console.log(`${h(str.length)} todolist before GC x ${h(diff1)}/tpl (${SAMPLE_COUNT} instances sampled)`)
+  console.log(`[todolist ${h(str.length)}][before GC] ${h(diff1)}/tpl (${SAMPLE_COUNT} runs sampled)`)
 
   global.gc()
   const diff2 = (getHeapStatistics().used_heap_size - base) / SAMPLE_COUNT
-  console.log(`${h(str.length)} todolist after GC x ${h(diff2)}/tpl (${SAMPLE_COUNT} instances sampled)`)
+  console.log(`[todolist ${h(str.length)}][after GC] ${h(diff2)}/tpl (${SAMPLE_COUNT} runs sampled)`)
 }
 
 function h (size) {
-  return (size / 1024).toFixed(3) + ' kB'
+  return (size / 1024).toFixed(3) + ' KB'
 }
 
 module.exports = { memory }

benchmark/output.js

@@ -4,7 +4,8 @@ const { Liquid } = require('..')
 const liquid = new Liquid()
 
 function output () {
-  console.log('--- output ---')
+  console.log('         output')
+  console.log('------------------------')
   return new Promise(resolve => {
     new Benchmark.Suite('output')
       .add('literal', test('{{false}}{{"foo"}}{{32.322}}'))

benchmark/package.json

@@ -0,0 +1,23 @@
+{
+  "name": "benchmark",
+  "private": true,
+  "version": "1.0.0",
+  "description": "",
+  "main": "index.js",
+  "scripts": {
+    "start": "node --expose-gc index",
+    "engines": "node -e 'require(\"./cross-engines\").crossEngines()'"
+  },
+  "author": "",
+  "license": "ISC",
+  "dependencies": {
+    "@babel/core": "^7.13.14",
+    "@babel/preset-env": "^7.13.12",
+    "@babel/preset-react": "^7.13.13",
+    "handlebars": "^4.7.7",
+    "react": "^17.0.2",
+    "react-dom": "^17.0.2",
+    "require-from-string": "^2.0.2",
+    "swig": "^1.4.2"
+  }
+}

benchmark/tag.js

@@ -4,7 +4,8 @@ const { Liquid } = require('..')
 const liquid = new Liquid()
 
 function tag () {
-  console.log('--- tag ---')
+  console.log('         tag')
+  console.log('------------------------')
   return new Promise(resolve => {
     new Benchmark.Suite('tag')
       .add('if', test('{% if "foobar" %}foo{% endif %}'))

benchmark/templates/todo-icon.hbs

@@ -0,0 +1 @@
+<img title="risus. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices" src="http://images.example.com/{{id}}.png">

benchmark/templates/todo-icon.liquid

@@ -0,0 +1 @@
+<img title="risus. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices" src="http://images.example.com/{{id}}.png">

benchmark/templates/todo-icon.swig

@@ -0,0 +1 @@
+<img title="risus. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices" src="http://images.example.com/{{todo.id}}.png">

benchmark/templates/todolist.hbs

@@ -0,0 +1,44 @@
+<section class="todo-list">
+    <h1>
+        posuere cubilia Curae; Vestibulum hendrerit malesuada odio. Fusce ut elit
+        ut augue sollicitudin blandit. Phasellus volutpat lorem. Duis non pede et
+        neque luctus tincidunt. Duis interdum tempus elit.
+        <small>Aenean metus. Vestibulum ac lacus. Vivamus porttitor, massa ut.</small>
+    </h1>
+    <a href={{url "/add"}} class="todo-add"><i class="fa fa-plus-square"></i>Add Todo</a>
+    <ul class="filter-category">
+        {{#each categories }}
+        <li style="background: {{ color }}">
+            <a href="/todos/category/{{ id }}">{{ title }}</a>
+        </li>
+        {{/each}}
+    </ul>
+    {{#each todos }}
+    <div>
+        <h2>
+            Todo {{inc @index}}:
+            <span class="todo-item content" data-todo-index="{{@index}}">
+                {{ upcase (concat 'TODO: ' title) }}
+            </span>
+        </h2>
+        {{> todo-icon id=id }}
+
+        <p class="description">
+            Purus eu mi. Proin commodo, massa commodo dapibus elementum,
+            libero lacus pulvinar eros, ut tincidunt nisl elit ut velit. Cras rutrum
+            porta purus. Vivamus lorem. Sed turpis enim, faucibus quis, pharetra in,
+            sagittis sed, magna. Curabitur ultricies felis ut libero. Nullam tincidunt
+            enim eu nibh. Nunc eget ipsum in sem facilisis convallis. Proin fermentum
+        </p>
+
+        <div class="todo-meta">
+            {{# if category }}
+                <span>{{ capitalize category }}</span>
+            {{/if}}
+        </div>
+        <a class="btn btn-primary" href={{ url (concat "/edit/" id) }}><i class="fa fa-pencil"></i> Edit</a>
+        <a class="btn btn-default"><i class="fa fa-check"></i> Check</a>
+        <a class="btn ben-danger" href={{ url (concat "/delete/" id) }}><i class="fa fa-trash-o"</i> Trash</a>
+    </div>
+    {{/each}}
+</section>

benchmark/templates/todolist.jsx

@@ -0,0 +1,57 @@
+// eslint-disable-next-line
+const React = require('react')
+
+function capitalize (str) {
+  return str[0].toUpperCase() + str.slice(1).toLowerCase()
+}
+function url (path) {
+  return `http://example.com${path}`
+}
+function renderTodoIcon (id) {
+  return <img title="risus. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices" src="http://images.example.com/{id}.png"/>
+}
+
+module.exports = ({ categories, todos }) => {
+  return <section className="todo-list">
+    <h1>
+            posuere cubilia Curae; Vestibulum hendrerit malesuada odio. Fusce ut elit
+            ut augue sollicitudin blandit. Phasellus volutpat lorem. Duis non pede et
+            neque luctus tincidunt. Duis interdum tempus elit.
+      <small>Aenean metus. Vestibulum ac lacus. Vivamus porttitor, massa ut.</small>
+    </h1>
+    <a href={url('/add')} className="todo-add"><i className="fa fa-plus-square"></i>Add Todo</a>
+    <ul className="filter-category">
+      {categories.map((item, i) => {
+        return <li key={i} style={{ background: item.color }}>
+          <a href={'/todos/category/' + item.id }>{ item.title }</a>
+        </li>
+      })}
+    </ul>
+    {todos.map((todo, index0) => {
+      return <div key={index0}>
+        <h2>
+                    Todo { index0 + 1 }:
+          <span className="todo-item content" data-todo-index="{{ forloop.index0 }}">
+            { ('TODO: ' + todo.title).toUpperCase() }
+          </span>
+        </h2>
+        { renderTodoIcon(todo.id) }
+
+        <p className="description">
+                    Purus eu mi. Proin commodo, massa commodo dapibus elementum,
+                    libero lacus pulvinar eros, ut tincidunt nisl elit ut velit. Cras rutrum
+                    porta purus. Vivamus lorem. Sed turpis enim, faucibus quis, pharetra in,
+                    sagittis sed, magna. Curabitur ultricies felis ut libero. Nullam tincidunt
+                    enim eu nibh. Nunc eget ipsum in sem facilisis convallis. Proin fermentum
+        </p>
+
+        <div className="todo-meta">
+          { todo.category ? <span>{capitalize(todo.category)}</span> : '' }
+        </div>
+        <a className="btn btn-primary" href={url('/edit/' + todo.id)}><i className="fa fa-pencil"></i> Edit</a>
+        <a className="btn btn-default"><i className="fa fa-check"></i> Check</a>
+        <a className="btn ben-danger" href={url('/delete/' + todo.id)}><i className="fa fa-trash-o"></i> Trash</a>
+      </div>
+    })}
+  </section>
+}

benchmark/templates/todolist.liquid

@@ -7,8 +7,7 @@
     </h1>
     <a href={{"/add" | url}} class="todo-add"><i class="fa fa-plus-square"></i>Add Todo</a>
     <ul class="filter-category">
-        {% for i in (0..categories.length) %}
-        {% assign item=categories[i] %}
+        {% for item in categories %}
         <li style="background: {{ item.color }}">
             <a href="/todos/category/{{ item.id }}">{{ item.title }}</a>
         </li>
@@ -22,11 +21,7 @@
                 {{ todo.title | prepend: 'TODO: ' | upcase }}
             </span>
         </h2>
-    
-        <img
-            title="risus. Vestibulum ante ipsum primis in faucibus orci luctus et ultrices"
-            src="{% include "todo-icon", id=todo.id }} %}"
-        >
+        {% render "todo-icon", id:todo.id %}
 
         <p class="description">
             Purus eu mi. Proin commodo, massa commodo dapibus elementum,
@@ -38,12 +33,12 @@
 
         <div class="todo-meta">
             {% if todo.category %}
-                <span>{{  todo.category.title | capitalize }}</span>
+                <span>{{  todo.category | capitalize }}</span>
             {% endif %}
         </div>
-        <a class="btn btn-primary" href={{"/edit/" | append todo.id | url }}><i class="fa fa-pencil"></i> Edit</a>
+        <a class="btn btn-primary" href={{"/edit/" | append: todo.id | url }}><i class="fa fa-pencil"></i> Edit</a>
         <a class="btn btn-default"><i class="fa fa-check"></i> Check</a>
-        <a class="btn ben-danger" href={{"/delete/" | append todo.id | url }}><i class="fa fa-trash-o"</i> Trash</a>
+        <a class="btn ben-danger" href={{"/delete/" | append: todo.id | url }}><i class="fa fa-trash-o"</i> Trash</a>
     </div>
     {% endfor %}
 </section>

benchmark/templates/todolist.swig

@@ -0,0 +1,44 @@
+<section class="todo-list">
+    <h1>
+        posuere cubilia Curae; Vestibulum hendrerit malesuada odio. Fusce ut elit
+        ut augue sollicitudin blandit. Phasellus volutpat lorem. Duis non pede et
+        neque luctus tincidunt. Duis interdum tempus elit.
+        <small>Aenean metus. Vestibulum ac lacus. Vivamus porttitor, massa ut.</small>
+    </h1>
+    <a href={{"/add" | url}} class="todo-add"><i class="fa fa-plus-square"></i>Add Todo</a>
+    <ul class="filter-category">
+        {% for item in categories %}
+        <li style="background: {{ item.color }}">
+            <a href="/todos/category/{{ item.id }}">{{ item.title }}</a>
+        </li>
+        {% endfor %}
+    </ul>
+    {% for todo in todos %}
+    <div>
+        <h2>
+            Todo {{ loop.index }}:
+            <span class="todo-item content" data-todo-index="{{ loop.index0 }}">
+                {{ todo.title | prepend('TODO: ') | upcase }}
+            </span>
+        </h2>
+        {% include "todo-icon.swig" %}
+
+        <p class="description">
+            Purus eu mi. Proin commodo, massa commodo dapibus elementum,
+            libero lacus pulvinar eros, ut tincidunt nisl elit ut velit. Cras rutrum
+            porta purus. Vivamus lorem. Sed turpis enim, faucibus quis, pharetra in,
+            sagittis sed, magna. Curabitur ultricies felis ut libero. Nullam tincidunt
+            enim eu nibh. Nunc eget ipsum in sem facilisis convallis. Proin fermentum
+        </p>
+
+        <div class="todo-meta">
+            {% if todo.category %}
+                <span>{{ todo.category | capitalize }}</span>
+            {% endif %}
+        </div>
+        <a class="btn btn-primary" href={{"/edit/" | append(todo.id) | url }}><i class="fa fa-pencil"></i> Edit</a>
+        <a class="btn btn-default"><i class="fa fa-check"></i> Check</a>
+        <a class="btn ben-danger" href={{"/delete/" | append(todo.id) | url }}><i class="fa fa-trash-o"</i> Trash</a>
+    </div>
+    {% endfor %}
+</section>

package.json

@@ -15,14 +15,15 @@
     "check": "npm test && npm run lint",
     "unit": "mocha \"test/unit/**/*.ts\"",
     "integration": "mocha \"test/integration/**/*.ts\"",
-    "e2e": "npm run build && mocha \"test/e2e/**/*.ts\"",
+    "e2e": "mocha \"test/e2e/**/*.ts\"",
     "test": "cross-env BUNDLES=cjs,umd npm run build && mocha \"test/**/*.ts\"",
-    "benchmark": "node --expose-gc benchmark/index",
+    "benchmark:prepare": "cd benchmark && npm ci",
+    "benchmark": "cd benchmark && npm start",
+    "benchmark:engines": "cd benchmark && npm run engines",
     "coverage": "nyc --reporter=html mocha \"test/{unit,integration}/**/*.ts\"",
     "coverage-coveralls": "nyc mocha \"test/{unit,integration}/**/*.ts\" && nyc report --reporter=text-lcov | coveralls",
     "build": "rm -rf dist && rollup -c rollup.config.ts && ls -lh dist",
-    "build-docs": "bin/build-docs.sh",
-    "watch": "tsc --watch"
+    "build-docs": "bin/build-docs.sh"
   },
   "bin": {
     "liquidjs": "./bin/liquid.js",
@@ -59,7 +60,7 @@
   },
   "homepage": "https://github.com/harttle/liquidjs#readme",
   "devDependencies": {
-    "@commitlint/cli": "^8.2.0",
+    "@commitlint/cli": "^12.1.4",
     "@commitlint/config-conventional": "^8.2.0",
     "@semantic-release/changelog": "^3.0.2",
     "@semantic-release/commit-analyzer": "^6.1.0",
@@ -93,13 +94,13 @@
     "express": "^4.16.4",
     "husky": "^4.2.5",
     "jsdom": "^13.2.0",
-    "mocha": "^5.2.0",
-    "nyc": "^13.1.0",
+    "mocha": "^9.0.1",
+    "nyc": "^15.1.0",
     "regenerator-runtime": "^0.12.1",
     "rollup": "^1.1.2",
     "rollup-plugin-replace": "^2.1.0",
     "rollup-plugin-typescript2": "^0.21.1",
-    "rollup-plugin-uglify": "^6.0.2",
+    "rollup-plugin-uglify": "^5.0.2",
     "semantic-release": "^17.2.3",
     "sinon": "^7.5.0",
     "sinon-chai": "^3.3.0",
@@ -141,6 +142,7 @@
       "pre-commit": "npm run check",
       "commit-msg": "commitlint -E HUSKY_GIT_PARAMS"
     }
-  },
-  "dependencies": {}
+  }
 }
+
+

src/builtin/filters/string.ts

@@ -7,12 +7,12 @@ import { stringify } from '../../util/underscore'
 import { assert } from '../../util/assert'
 
 export function append (v: string, arg: string) {
-  assert(arg !== undefined, () => 'append expect 2 arguments')
+  assert(arguments.length === 2, () => 'append expect 2 arguments')
   return stringify(v) + stringify(arg)
 }
 
 export function prepend (v: string, arg: string) {
-  assert(arg !== undefined, () => 'prepend expect 2 arguments')
+  assert(arguments.length === 2, () => 'prepend expect 2 arguments')
   return stringify(arg) + stringify(v)
 }
 

src/builtin/tags/include.ts

@@ -24,6 +24,7 @@ export default {
   render: function * (ctx: Context, emitter: Emitter) {
     const { liquid, hash, withVar, file } = this
     const { renderer } = liquid
+    // TODO try move all liquid.parse calls into parse() section
     const filepath = ctx.opts.dynamicPartials
       ? (TypeGuards.isQuotedToken(file)
         ? yield renderer.renderTemplates(liquid.parse(evalQuotedToken(file)), ctx)

test/integration/builtin/filters/string.ts

@@ -9,9 +9,6 @@ describe('filters/string', function () {
     it('should return "-3abc" for -3, "abc"',
       () => test('{{ -3 | append: "abc" }}', '-3abc'))
     it('should return "abar" for "a", foo', () => test('{{ "a" | append: foo }}', { foo: 'bar' }, 'abar'))
-    it('should throw if second argument undefined', () => {
-      return expect(test('{{ "abc" | append: undefinedVar }}', 'abc')).to.be.rejectedWith(/2 arguments/)
-    })
     it('should throw if second argument not set', () => {
       return expect(test('{{ "abc" | append }}', 'abc')).to.be.rejectedWith(/2 arguments/)
     })
@@ -21,9 +18,6 @@ describe('filters/string', function () {
     it('should return "-3abc" for -3, "abc"',
       () => test('{{ -3 | prepend: "abc" }}', 'abc-3'))
     it('should return "abar" for "a", foo', () => test('{{ "a" | prepend: foo }}', { foo: 'bar' }, 'bara'))
-    it('should throw if second argument undefined', () => {
-      return expect(test('{{ "abc" | prepend: undefinedVar }}', 'abc')).to.be.rejectedWith(/2 arguments/)
-    })
     it('should throw if second argument not set', () => {
       return expect(test('{{ "abc" | prepend }}', 'abc')).to.be.rejectedWith(/2 arguments/)
     })

test/mocha.opts

@@ -1 +0,0 @@
---require ts-node/register/transpile-only --strict false