fix: throws on invalid arguments for prepend/append, fixes #208

src/builtin/filters/array.ts

@@ -1,42 +1,35 @@
-import { isArray, last } from '../../util/underscore'
+import { isArray, last as arrayLast } from '../../util/underscore'
 import { isTruthy } from '../../render/boolean'
 import { FilterImpl } from '../../template/filter/filter-impl'
 
-export default {
-  'join': (v: any[], arg: string) => v.join(arg === undefined ? ' ' : arg),
-  'last': (v: any) => isArray(v) ? last(v) : '',
-  'first': (v: any) => isArray(v) ? v[0] : '',
-  'map': map,
-  'reverse': (v: any[]) => [...v].reverse(),
-  'sort': <T>(v: T[], arg: (lhs: T, rhs: T) => number) => v.sort(arg),
-  'size': (v: string | any[]) => (v && v.length) || 0,
-  'concat': concat,
-  'slice': slice,
-  'uniq': uniq,
-  'where': where
-}
+export const join = (v: any[], arg: string) => v.join(arg === undefined ? ' ' : arg)
+export const last = (v: any) => isArray(v) ? arrayLast(v) : ''
+export const first = (v: any) => isArray(v) ? v[0] : ''
+export const reverse = (v: any[]) => [...v].reverse()
+export const sort = <T>(v: T[], arg: (lhs: T, rhs: T) => number) => v.sort(arg)
+export const size = (v: string | any[]) => (v && v.length) || 0
 
-function map<T1, T2> (arr: {[key: string]: T1}[], arg: string): T1[] {
+export function map<T1, T2> (arr: {[key: string]: T1}[], arg: string): T1[] {
   return arr.map(v => v[arg])
 }
 
-function concat<T1, T2> (v: T1[], arg: T2[] | T2): (T1 | T2)[] {
+export function concat<T1, T2> (v: T1[], arg: T2[] | T2): (T1 | T2)[] {
   return Array.prototype.concat.call(v, arg)
 }
 
-function slice<T> (v: T[], begin: number, length = 1): T[] {
+export function slice<T> (v: T[], begin: number, length = 1): T[] {
   begin = begin < 0 ? v.length + begin : begin
   return v.slice(begin, begin + length)
 }
 
-function where<T extends object> (this: FilterImpl, arr: T[], property: string, expected?: any): T[] {
+export function where<T extends object> (this: FilterImpl, arr: T[], property: string, expected?: any): T[] {
   return arr.filter(obj => {
     const value = this.context.getFromScope(obj, property.split('.'))
     return expected === undefined ? isTruthy(value) : value === expected
   })
 }
 
-function uniq<T> (arr: T[]): T[] {
+export function uniq<T> (arr: T[]): T[] {
   const u = {}
   return (arr || []).filter(val => {
     if (u.hasOwnProperty(String(val))) return false

src/builtin/filters/date.ts

@@ -1,18 +1,16 @@
 import strftime from '../../util/strftime'
 import { isString, isNumber } from '../../util/underscore'
 
-export default {
-  'date': (v: string | Date, arg: string) => {
-    let date = v
-    if (v === 'now' || v === 'today') {
-      date = new Date()
-    } else if (isNumber(v)) {
-      date = new Date(v * 1000)
-    } else if (isString(v)) {
-      date = /^\d+$/.test(v) ? new Date(+v * 1000) : new Date(v)
-    }
-    return isValidDate(date) ? strftime(date, arg) : v
+export function date (v: string | Date, arg: string) {
+  let date = v
+  if (v === 'now' || v === 'today') {
+    date = new Date()
+  } else if (isNumber(v)) {
+    date = new Date(v * 1000)
+  } else if (isString(v)) {
+    date = /^\d+$/.test(v) ? new Date(+v * 1000) : new Date(v)
   }
+  return isValidDate(date) ? strftime(date, arg) : v
 }
 
 function isValidDate (date: any): date is Date {

src/builtin/filters/html.ts

@@ -15,7 +15,7 @@ const unescapeMap = {
   ''': "'"
 }
 
-function escape (str: string) {
+export function escape (str: string) {
   return stringify(str).replace(/&|<|>|"|'/g, m => escapeMap[m])
 }
 
@@ -23,9 +23,14 @@ function unescape (str: string) {
   return String(str).replace(/&(amp|lt|gt|#34|#39);/g, m => unescapeMap[m])
 }
 
-export default {
-  'escape': escape,
-  'escape_once': (str: string) => escape(unescape(str)),
-  'newline_to_br': (v: string) => v.replace(/\n/g, '<br />'),
-  'strip_html': (v: string) => v.replace(/<script.*?<\/script>|<!--.*?-->|<style.*?<\/style>|<.*?>/g, '')
+export function escapeOnce (str: string) {
+  return escape(unescape(str))
+}
+
+export function newlineToBr (v: string) {
+  return v.replace(/\n/g, '<br />')
+}
+
+export function stripHtml (v: string) {
+  return v.replace(/<script.*?<\/script>|<!--.*?-->|<style.*?<\/style>|<.*?>/g, '')
 }

src/builtin/filters/index.ts

@@ -1,9 +1,7 @@
-import html from './html'
-import str from './string'
-import math from './math'
-import url from './url'
-import array from './array'
-import date from './date'
-import obj from './object'
-
-export default { ...html, ...str, ...math, ...url, ...date, ...obj, ...array }
+export * from './html'
+export * from './math'
+export * from './url'
+export * from './array'
+export * from './date'
+export * from './object'
+export * from './string'

src/builtin/filters/math.ts

@@ -1,24 +1,25 @@
 import { caseInsensitiveCompare } from '../../util/underscore'
 
-export default {
-  'abs': (v: number) => Math.abs(v),
-  'at_least': (v: number, n: number) => Math.max(v, n),
-  'at_most': (v: number, n: number) => Math.min(v, n),
-  'ceil': (v: number) => Math.ceil(v),
-  'divided_by': (v: number, arg: number) => v / arg,
-  'floor': (v: number) => Math.floor(v),
-  'minus': (v: number, arg: number) => v - arg,
-  'modulo': (v: number, arg: number) => v % arg,
-  'round': (v: number, arg = 0) => {
-    const amp = Math.pow(10, arg)
-    return Math.round(v * amp) / amp
-  },
-  'plus': (v: number, arg: number) => Number(v) + Number(arg),
-  'sort_natural': sortNatural,
-  'times': (v: number, arg: number) => v * arg
+export const abs = Math.abs
+export const atLeast = Math.max
+export const atMost = Math.min
+export const ceil = Math.ceil
+export const dividedBy = (v: number, arg: number) => v / arg
+export const floor = Math.floor
+export const minus = (v: number, arg: number) => v - arg
+export const modulo = (v: number, arg: number) => v % arg
+export const times = (v: number, arg: number) => v * arg
+
+export function round (v: number, arg = 0) {
+  const amp = Math.pow(10, arg)
+  return Math.round(v * amp) / amp
 }
 
-function sortNatural (input: any[], property?: string) {
+export function plus (v: number, arg: number) {
+  return Number(v) + Number(arg)
+}
+
+export function sortNatural (input: any[], property?: string) {
   if (!input || !input.sort) return []
   if (property !== undefined) {
     return [...input].sort(

src/builtin/filters/object.ts

@@ -1,11 +1,9 @@
 import { isFalsy } from '../../render/boolean'
 import { toValue } from '../../util/underscore'
 
-export default {
-  'default': function<T1, T2> (v: string | T1, arg: T2): string | T1 | T2 {
-    return isFalsy(toValue(v)) || v === '' ? arg : v
-  },
-  'json': function (v: any) {
-    return JSON.stringify(v)
-  }
+export function Default<T1, T2> (v: string | T1, arg: T2): string | T1 | T2 {
+  return isFalsy(toValue(v)) || v === '' ? arg : v
+}
+export function json (v: any) {
+  return JSON.stringify(v)
 }

src/builtin/filters/string.ts

@@ -4,46 +4,74 @@
  * * prefer stringify() to String() since `undefined`, `null` should eval ''
  */
 import { stringify } from '../../util/underscore'
+import { assert } from '../../util/assert'
 
-export default {
-  'append': (v: string, arg: string) => stringify(v) + stringify(arg),
-  'prepend': (v: string, arg: string) => stringify(arg) + stringify(v),
-  'capitalize': capitalize,
-  'lstrip': (v: string) => stringify(v).replace(/^\s+/, ''),
-  'downcase': (v: string) => stringify(v).toLowerCase(),
-  'upcase': (str: string) => stringify(str).toUpperCase(),
-  'remove': (v: string, arg: string) => stringify(v).split(arg).join(''),
-  'remove_first': (v: string, l: string) => stringify(v).replace(l, ''),
-  'replace': replace,
-  'replace_first': replaceFirst,
-  'rstrip': (str: string) => stringify(str).replace(/\s+$/, ''),
-  'split': (v: string, arg: string) => stringify(v).split(arg),
-  'strip': (v: string) => stringify(v).trim(),
-  'strip_newlines': (v: string) => stringify(v).replace(/\n/g, ''),
-  'truncate': truncate,
-  'truncatewords': truncateWords
+export function append (v: string, arg: string) {
+  assert(arg !== undefined, () => 'append expect 2 arguments')
+  return stringify(v) + stringify(arg)
 }
 
-function capitalize (str: string) {
+export function prepend (v: string, arg: string) {
+  assert(arg !== undefined, () => 'prepend expect 2 arguments')
+  return stringify(arg) + stringify(v)
+}
+
+export function lstrip (v: string) {
+  return stringify(v).replace(/^\s+/, '')
+}
+
+export function downcase (v: string) {
+  return stringify(v).toLowerCase()
+}
+
+export function upcase (str: string) {
+  return stringify(str).toUpperCase()
+}
+
+export function remove (v: string, arg: string) {
+  return stringify(v).split(arg).join('')
+}
+
+export function removeFirst (v: string, l: string) {
+  return stringify(v).replace(l, '')
+}
+
+export function rstrip (str: string) {
+  return stringify(str).replace(/\s+$/, '')
+}
+
+export function split (v: string, arg: string) {
+  return stringify(v).split(arg)
+}
+
+export function strip (v: string) {
+  return stringify(v).trim()
+}
+
+export function stripNewlines (v: string) {
+  return stringify(v).replace(/\n/g, '')
+}
+
+export function capitalize (str: string) {
   str = stringify(str)
   return str.charAt(0).toUpperCase() + str.slice(1)
 }
 
-function replace (v: string, pattern: string, replacement: string) {
+export function replace (v: string, pattern: string, replacement: string) {
   return stringify(v).split(pattern).join(replacement)
 }
 
-function replaceFirst (v: string, arg1: string, arg2: string) {
+export function replaceFirst (v: string, arg1: string, arg2: string) {
   return stringify(v).replace(arg1, arg2)
 }
 
-function truncate (v: string, l = 50, o = '...') {
+export function truncate (v: string, l = 50, o = '...') {
   v = stringify(v)
   if (v.length <= l) return v
   return v.substr(0, l - o.length) + o
 }
 
-function truncateWords (v: string, l = 15, o = '...') {
+export function truncatewords (v: string, l = 15, o = '...') {
   const arr = v.split(/\s+/)
   let ret = arr.slice(0, l).join(' ')
   if (arr.length >= l) ret += o

src/builtin/filters/url.ts

@@ -1,4 +1,2 @@
-export default {
-  'url_decode': (x: string) => x.split('+').map(decodeURIComponent).join(' '),
-  'url_encode': (x: string) => x.split(' ').map(encodeURIComponent).join('+')
-}
+export const urlDecode = (x: string) => x.split('+').map(decodeURIComponent).join(' ')
+export const urlEncode = (x: string) => x.split(' ').map(encodeURIComponent).join('+')

src/liquid.ts

@@ -1,6 +1,6 @@
 import { Context } from './context/context'
 import * as fs from './fs/node'
-import * as _ from './util/underscore'
+import { forOwn, snakeCase } from './util/underscore'
 import { Template } from './template/template'
 import { Tokenizer } from './parser/tokenizer'
 import { Render } from './render/render'
@@ -8,7 +8,7 @@ import Parser from './parser/parser'
 import { TagImplOptions } from './template/tag/tag-impl-options'
 import { Value } from './template/value'
 import builtinTags from './builtin/tags'
-import builtinFilters from './builtin/filters'
+import * as builtinFilters from './builtin/filters'
 import { TagMap } from './template/tag/tag-map'
 import { FilterMap } from './template/filter/filter-map'
 import { LiquidOptions, normalizeStringArray, NormalizedFullOptions, applyDefault, normalize } from './liquid-options'
@@ -34,8 +34,8 @@ export class Liquid {
     this.filters = new FilterMap(this.options.strictFilters)
     this.tags = new TagMap()
 
-    _.forOwn(builtinTags, (conf, name) => this.registerTag(name, conf))
-    _.forOwn(builtinFilters, (handler, name) => this.registerFilter(name, handler))
+    forOwn(builtinTags, (conf, name) => this.registerTag(snakeCase(name), conf))
+    forOwn(builtinFilters, (handler, name) => this.registerFilter(snakeCase(name), handler))
   }
   public parse (html: string, filepath?: string): Template[] {
     const tokenizer = new Tokenizer(html, filepath)

src/util/underscore.ts

@@ -120,6 +120,13 @@ export function identify<T> (val: T): T {
   return val
 }
 
+export function snakeCase (str: string) {
+  return str.replace(
+    /(\w?)([A-Z])/g,
+    (_, a, b) => (a ? a + '_' : '') + b.toLowerCase()
+  )
+}
+
 export function changeCase (str: string): string {
   const hasLowerCase = [...str].some(ch => ch >= 'a' && ch <= 'z')
   return hasLowerCase ? str.toUpperCase() : str.toLowerCase()

test/integration/builtin/filters/html.ts

@@ -22,6 +22,19 @@ describe('filters/html', function () {
     it('should not escape twice',
       () => test('{{ "1 < 2 & 3" | escape_once }}', '1 < 2 & 3'))
   })
+  describe('newline_to_br', function () {
+    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('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 }}',

test/integration/builtin/filters/string.ts

@@ -1,6 +1,9 @@
 import { test } from '../../../stub/render'
 import { Liquid } from '../../../../src/liquid'
-import { expect } from 'chai'
+import { expect, use } from 'chai'
+import * as chaiAsPromised from 'chai-as-promised'
+
+use(chaiAsPromised)
 
 describe('filters/string', function () {
   let liquid: Liquid
@@ -11,14 +14,24 @@ 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 }}', 'abar'))
-    it('should return "abc" for "abc", undefined', () => test('{{ "abc" | append: undefinedVar }}', 'abc'))
+    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/)
+    })
     it('should return "abcfalse" for "abc", false', () => test('{{ "abc" | append: false }}', 'abcfalse'))
   })
   describe('prepend', 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 }}', 'bara'))
-    it('should return "abc" for "abc", undefined', () => test('{{ "abc" | prepend: undefinedVar }}', 'abc'))
+    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/)
+    })
     it('should return "falseabc" for "abc", false', () => test('{{ "abc" | prepend: false }}', 'falseabc'))
   })
   describe('capitalize', function () {
@@ -105,17 +118,6 @@ describe('filters/string', 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 }}',

test/unit/util/underscore.ts

@@ -7,6 +7,15 @@ const expect = chai.expect
 chai.use(sinonChai)
 
 describe('util/underscore', function () {
+  describe('.camel2snake()', function () {
+    it('should convert camelCase to snakeCase', function () {
+      expect(_.snakeCase('fooBarCoo')).to.equal('foo_bar_coo')
+    })
+    it('should convert empty string to empty string', function () {
+      expect(_.snakeCase('')).to.equal('')
+    })
+  })
+
   describe('.isString()', function () {
     it('should return true for literal string', function () {
       expect(_.isString('foo')).to.be.true