diff --git a/src/builtin/filters/array.ts b/src/builtin/filters/array.ts
index e9693795a..2e539d9d9 100644
--- a/src/builtin/filters/array.ts
+++ b/src/builtin/filters/array.ts
@@ -1,4 +1,5 @@
 import { isArray, last as arrayLast } from '../../util/underscore'
+import { toArray } from '../../util/collection'
 import { isTruthy } from '../../render/boolean'
 import { FilterImpl } from '../../template/filter/filter-impl'
 
@@ -10,11 +11,11 @@ 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
 
 export function map<T1, T2> (arr: {[key: string]: T1}[], arg: string): T1[] {
-  return arr.map(v => v[arg])
+  return toArray(arr).map(v => v[arg])
 }
 
 export function concat<T1, T2> (v: T1[], arg: T2[] | T2): (T1 | T2)[] {
-  return Array.prototype.concat.call(v, arg)
+  return toArray(v).concat(arg)
 }
 
 export function slice<T> (v: T[], begin: number, length = 1): T[] {
@@ -23,8 +24,8 @@ export function slice<T> (v: T[], begin: number, length = 1): 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 toArray(arr).filter(obj => {
+    const value = this.context.getFromScope(obj, String(property).split('.'))
     return expected === undefined ? isTruthy(value) : value === expected
   })
 }
diff --git a/src/builtin/tags/for.ts b/src/builtin/tags/for.ts
index c2fdcfda1..276be8cc2 100644
--- a/src/builtin/tags/for.ts
+++ b/src/builtin/tags/for.ts
@@ -1,5 +1,5 @@
 import { assert, Tokenizer, evalToken, Emitter, TagToken, TopLevelToken, Context, Template, TagImplOptions, ParseStream } from '../../types'
-import { toCollection } from '../../util/collection'
+import { toEnumerable } from '../../util/collection'
 import { ForloopDrop } from '../../drop/forloop-drop'
 import { Hash } from '../../template/tag/hash'
 
@@ -36,7 +36,7 @@ export default {
   },
   render: function * (ctx: Context, emitter: Emitter) {
     const r = this.liquid.renderer
-    let collection = toCollection(evalToken(this.collection, ctx))
+    let collection = toEnumerable(evalToken(this.collection, ctx))
 
     if (!collection.length) {
       yield r.renderTemplates(this.elseTemplates, ctx, emitter)
diff --git a/src/builtin/tags/render.ts b/src/builtin/tags/render.ts
index 86eda1ba6..f6fe37224 100644
--- a/src/builtin/tags/render.ts
+++ b/src/builtin/tags/render.ts
@@ -1,6 +1,6 @@
 import { assert } from '../../util/assert'
 import { ForloopDrop } from '../../drop/forloop-drop'
-import { toCollection } from '../../util/collection'
+import { toEnumerable } from '../../util/collection'
 import { evalQuotedToken, TypeGuards, Tokenizer, evalToken, Hash, Emitter, TagToken, Context, TagImplOptions } from '../../types'
 
 export default {
@@ -60,7 +60,7 @@ export default {
     if (this['for']) {
       const { value, alias } = this['for']
       let collection = evalToken(value, ctx)
-      collection = toCollection(collection)
+      collection = toEnumerable(collection)
       scope['forloop'] = new ForloopDrop(collection.length)
       for (const item of collection) {
         scope[alias] = item
diff --git a/src/builtin/tags/tablerow.ts b/src/builtin/tags/tablerow.ts
index 48bc08817..81d167232 100644
--- a/src/builtin/tags/tablerow.ts
+++ b/src/builtin/tags/tablerow.ts
@@ -1,4 +1,4 @@
-import { toCollection } from '../../util/collection'
+import { toEnumerable } from '../../util/collection'
 import { assert, evalToken, Emitter, Hash, TagToken, TopLevelToken, Context, Template, TagImplOptions, ParseStream } from '../../types'
 import { TablerowloopDrop } from '../../drop/tablerowloop-drop'
 import { Tokenizer } from '../../parser/tokenizer'
@@ -30,7 +30,7 @@ export default {
   },
 
   render: function * (ctx: Context, emitter: Emitter) {
-    let collection = toCollection(evalToken(this.collection, ctx))
+    let collection = toEnumerable(evalToken(this.collection, ctx))
     const hash = yield this.hash.render(ctx)
     const offset = hash.offset || 0
     const limit = (hash.limit === undefined) ? collection.length : hash.limit
diff --git a/src/template/value.ts b/src/template/value.ts
index 36847ab8d..e8ef76563 100644
--- a/src/template/value.ts
+++ b/src/template/value.ts
@@ -16,7 +16,6 @@ export class Value {
     const tokenizer = new Tokenizer(str)
     this.initial = tokenizer.readValue()
     this.filters = tokenizer.readFilters().map(({ name, args }) => new Filter(name, this.filterMap.get(name), args))
-    tokenizer.skipBlank()
   }
   public * value (ctx: Context) {
     let val = yield evalToken(this.initial, ctx)
diff --git a/src/util/collection.ts b/src/util/collection.ts
index 9f890e479..edbeeb886 100644
--- a/src/util/collection.ts
+++ b/src/util/collection.ts
@@ -1,8 +1,13 @@
 import { isString, isObject, isArray } from './underscore'
 
-export function toCollection (val: any) {
+export function toEnumerable (val: any) {
   if (isArray(val)) return val
   if (isString(val) && val.length > 0) return [val]
   if (isObject(val)) return Object.keys(val).map((key) => [key, val[key]])
   return []
 }
+
+export function toArray (val: any) {
+  if (isArray(val)) return val
+  return [ val ]
+}
diff --git a/test/integration/builtin/filters/array.ts b/test/integration/builtin/filters/array.ts
index d615082b8..e519f7f76 100644
--- a/test/integration/builtin/filters/array.ts
+++ b/test/integration/builtin/filters/array.ts
@@ -1,14 +1,9 @@
-import { test } from '../../../stub/render'
-import { Liquid } from '../../../../src/liquid'
+import { test, render } from '../../../stub/render'
 import { expect, use } from 'chai'
 import * as chaiAsPromised from 'chai-as-promised'
 use(chaiAsPromised)
 
 describe('filters/array', function () {
-  let liquid: Liquid
-  beforeEach(function () {
-    liquid = new Liquid()
-  })
   describe('index', function () {
     it('should support index', function () {
       const src = '{% assign beatles = "John, Paul, George, Ringo" | split: ", " %}' +
@@ -30,7 +25,7 @@ describe('filters/array', function () {
     it('should throw when comma missing', async () => {
       const src = '{% assign beatles = "John, Paul, George, Ringo" | split: ", " %}' +
         '{{ beatles | join " and " }}'
-      return expect(liquid.parseAndRender(src)).to.be.rejectedWith('unexpected token at "\\" and \\"", line:1, col:65')
+      return expect(render(src)).to.be.rejectedWith('unexpected token at "\\" and \\"", line:1, col:65')
     })
   })
   it('should support split/last', function () {
@@ -38,101 +33,70 @@ describe('filters/array', function () {
       '{{ my_array|last }}'
     return test(src, 'tiger')
   })
-  it('should support map', function () {
-    return test('{{posts | map: "category"}}', 'foo,bar')
+  describe('map', () => {
+    it('should support map', function () {
+      const posts = [{ category: 'foo' }, { category: 'bar' }]
+      return test('{{posts | map: "category"}}', { posts }, 'foo,bar')
+    })
+    it('should normalize non-array input', function () {
+      const post = { category: 'foo' }
+      return test('{{post | map: "category"}}', { post }, 'foo')
+    })
   })
   describe('reverse', function () {
-    it('should support reverse', async function () {
-      const html = await liquid.parseAndRender('{{ "Ground control to Major Tom." | split: "" | reverse | join: "" }}')
-      expect(html).to.equal('.moT rojaM ot lortnoc dnuorG')
-    })
-    it('should be pure', async function () {
+    it('should support reverse', () => test(
+      '{{ "Ground control to Major Tom." | split: "" | reverse | join: "" }}',
+      '.moT rojaM ot lortnoc dnuorG'
+    ))
+    it('should be pure', async () => {
       const scope = { arr: ['a', 'b', 'c'] }
-      await liquid.parseAndRender('{{ arr | reverse | join: "" }}', scope)
-      const html = await liquid.parseAndRender('{{ arr | join: "" }}', scope)
+      await render('{{ arr | reverse | join: "" }}', scope)
+      const html = await render('{{ arr | join: "" }}', scope)
       expect(html).to.equal('abc')
     })
   })
   describe('size', function () {
-    it('should return string length', async () => {
-      const html = await liquid.parseAndRender('{{ "Ground control to Major Tom." | size }}')
-      expect(html).to.equal('28')
-    })
-    it('should return array size', async () => {
-      const html = await liquid.parseAndRender(
-        '{% assign my_array = "apples, oranges, peaches, plums" | split: ", " %}{{ my_array | size }}')
-      expect(html).to.equal('4')
-    })
-    it('should be respected with <string>.size notation', async () => {
-      const html = await liquid.parseAndRender('{% assign my_string = "Ground control to Major Tom." %}{{ my_string.size }}')
-      expect(html).to.equal('28')
-    })
-    it('should be respected with <array>.size notation', async () => {
-      const html = await liquid.parseAndRender('{% assign my_array = "apples, oranges, peaches, plums" | split: ", " %}{{ my_array.size }}')
-      expect(html).to.equal('4')
-    })
-    it('should return 0 for false', async () => {
-      const html = await liquid.parseAndRender('{{ false | size }}')
-      expect(html).to.equal('0')
-    })
-    it('should return 0 for nil', async () => {
-      const html = await liquid.parseAndRender('{{ nil | size }}')
-      expect(html).to.equal('0')
-    })
-    it('should return 0 for undefined', async () => {
-      const html = await liquid.parseAndRender('{{ foo | size }}')
-      expect(html).to.equal('0')
-    })
+    it('should return string length', () => test(
+      '{{ "Ground control to Major Tom." | size }}',
+      '28'
+    ))
+    it('should return array size', () => test(
+      '{% assign my_array = "apples, oranges, peaches, plums" | split: ", " %}{{ my_array | size }}',
+      '4'
+    ))
+    it('should be respected with <string>.size notation', () => test(
+      '{% assign my_string = "Ground control to Major Tom." %}{{ my_string.size }}',
+      '28'
+    ))
+    it('should be respected with <array>.size notation', () => test(
+      '{% assign my_array = "apples, oranges, peaches, plums" | split: ", " %}{{ my_array.size }}',
+      '4'
+    ))
+    it('should return 0 for false', () => test('{{ false | size }}', '0'))
+    it('should return 0 for nil', () => test('{{ nil | size }}', '0'))
+    it('should return 0 for undefined', () => test('{{ foo | size }}', '0'))
   })
   describe('first', function () {
-    it('should support first', async () => {
-      const html = await liquid.parseAndRender(
-        '{{arr | first}}',
-        { arr: [ 'zebra', 'tiger' ] }
-      )
-      expect(html).to.equal('zebra')
-    })
-    it('should return empty for nil', async () => {
-      const html = await liquid.parseAndRender('{{nil | first}}')
-      expect(html).to.equal('')
-    })
-    it('should return empty for undefined', async () => {
-      const html = await liquid.parseAndRender('{{foo | first}}')
-      expect(html).to.equal('')
-    })
-    it('should return empty for false', async () => {
-      const html = await liquid.parseAndRender('{{false | first}}')
-      expect(html).to.equal('')
-    })
-    it('should return empty for string', async () => {
-      const html = await liquid.parseAndRender('{{"zebra" | first}}')
-      expect(html).to.equal('')
-    })
+    it('should support first', () => test(
+      '{{arr | first}}',
+      { arr: [ 'zebra', 'tiger' ] },
+      'zebra'
+    ))
+    it('should return empty for nil', () => test('{{nil | first}}', ''))
+    it('should return empty for undefined', () => test('{{foo | first}}', ''))
+    it('should return empty for false', () => test('{{false | first}}', ''))
+    it('should return empty for string', () => test('{{"zebra" | first}}', ''))
   })
   describe('last', function () {
-    it('should support last', async () => {
-      const html = await liquid.parseAndRender(
-        '{{arr | last}}',
-        { arr: [ 'zebra', 'tiger' ] }
-      )
-      expect(html).to.equal('tiger')
-    })
-    it('should return empty for nil', async () => {
-      const html = await liquid.parseAndRender('{{nil | last}}')
-      expect(html).to.equal('')
-    })
-    it('should return empty for undefined', async () => {
-      const html = await liquid.parseAndRender('{{foo | last}}')
-      expect(html).to.equal('')
-    })
-    it('should return empty for false', async () => {
-      const html = await liquid.parseAndRender('{{false | last}}')
-      expect(html).to.equal('')
-    })
-    it('should return empty for string', async () => {
-      const html = await liquid.parseAndRender('{{"zebra" | last}}')
-      expect(html).to.equal('')
-    })
+    it('should support last', () => test(
+      '{{arr | last}}',
+      { arr: [ 'zebra', 'tiger' ] },
+      'tiger'
+    ))
+    it('should return empty for nil', () => test('{{nil | last}}', ''))
+    it('should return empty for undefined', () => test('{{foo | last}}', ''))
+    it('should return empty for false', () => test('{{false | last}}', ''))
+    it('should return empty for string', () => test('{{"zebra" | last}}', ''))
   })
   describe('slice', function () {
     it('should slice first char by 0', () => test('{{ "Liquid" | slice: 0 }}', 'L'))
@@ -161,44 +125,60 @@ describe('filters/array', function () {
     })
   })
   describe('where', function () {
+    const products = [
+      { title: 'Vacuum', type: 'living room' },
+      { title: 'Spatula', type: 'kitchen' },
+      { title: 'Television', type: 'living room' },
+      { title: 'Garlic press', type: 'kitchen' },
+      { title: 'Coffee mug', available: true },
+      { title: 'Limited edition sneakers', available: false },
+      { title: 'Boring sneakers', available: true }
+    ]
     it('should support filter by property value', function () {
       return test(`{% assign kitchen_products = products | where: "type", "kitchen" %}
-Kitchen products:
-{% for product in kitchen_products -%}
-- {{ product.title }}
-{% endfor %}`, `
-Kitchen products:
-- Spatula
-- Garlic press
-`)
+        Kitchen products:
+        {% for product in kitchen_products -%}
+        - {{ product.title }}
+        {% endfor %}`, { products }, `
+        Kitchen products:
+        - Spatula
+        - Garlic press
+        `)
     })
     it('should support filter truthy property', function () {
       return test(`{% assign available_products = products | where: "available" %}
-Available products:
-{% for product in available_products -%}
-- {{ product.title }}
-{% endfor %}`, `
-Available products:
-- Coffee mug
-- Boring sneakers
-`)
+        Available products:
+        {% for product in available_products -%}
+        - {{ product.title }}
+        {% endfor %}`, { products }, `
+        Available products:
+        - Coffee mug
+        - Boring sneakers
+        `)
     })
     it('should support nested property', async function () {
       const authors = [
         { name: 'Alice', books: { year: 2019 } },
         { name: 'Bob', books: { year: 2018 } }
       ]
-      const html = await liquid.parseAndRender(
+      return test(
         `{% assign recentAuthors = authors | where: 'books.year', 2019 %}
-Recent Authors:
-{%- for author in recentAuthors %}
-  - {{author.name}}
-{%- endfor %}`,
-        { authors }
-      )
-      expect(html).to.equal(`
-Recent Authors:
-  - Alice`)
+        Recent Authors:
+        {%- for author in recentAuthors %}
+          - {{author.name}}
+        {%- endfor %}`,
+        { authors }, `
+        Recent Authors:
+          - Alice`)
+    })
+    it('should apply to string', async () => {
+      await test('{{"abc" | where: 1, "b" }}', 'abc')
+      await test('{{"abc" | where: 1, "a" }}', '')
+    })
+    it('should normalize non-array input', async () => {
+      const scope = { obj: { foo: 'FOO' } }
+      await test('{{obj | where: "foo", "FOO" }}', scope, '[object Object]')
+      await test('{{obj | where: "foo", "BAR" }}', scope, '')
     })
   })
 })
diff --git a/test/integration/builtin/filters/date.ts b/test/integration/builtin/filters/date.ts
index e39b2edc8..7edc844bc 100644
--- a/test/integration/builtin/filters/date.ts
+++ b/test/integration/builtin/filters/date.ts
@@ -1,15 +1,9 @@
-import { test, ctx } from '../../../stub/render'
-import { expect } from 'chai'
-import { Liquid } from '../../../../src/liquid'
+import { test } from '../../../stub/render'
 
 describe('filters/date', function () {
-  let liquid: Liquid
-  beforeEach(function () {
-    liquid = new Liquid()
-  })
   it('should support date: %a %b %d %Y', function () {
-    const str = ctx.date.toDateString()
-    return test('{{ date | date:"%a %b %d %Y"}}', str)
+    const date = new Date()
+    return test('{{ date | date:"%a %b %d %Y"}}', { date }, date.toDateString())
   })
   it('should create a new Date when given "now"', function () {
     return test('{{ "now" | date: "%Y"}}', (new Date()).getFullYear().toString())
@@ -23,27 +17,21 @@ describe('filters/date', function () {
   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"}}', '[object Object]')
+  it('should render object as string', function () {
+    return test('{{ obj | date: "%Y"}}', { obj: {} }, '[object Object]')
   })
   it('should create from number', async function () {
     const time = new Date('2017-03-07T12:00:00').getTime() / 1000
-    const src = '{{ time | date: "%Y-%m-%dT%H:%M:%S" }}'
-    const ctx = { time }
-    const dst = '2017-03-07T12:00:00'
-    expect(await liquid.parseAndRender(src, ctx)).to.equal(dst)
+    return test('{{ time | date: "%Y-%m-%dT%H:%M:%S" }}', { time }, '2017-03-07T12:00:00')
   })
   it('should create from number-like string', async function () {
     const time = String(new Date('2017-03-07T12:00:00').getTime() / 1000)
-    const src = '{{ time | date: "%Y-%m-%dT%H:%M:%S" }}'
-    const ctx = { time }
-    const dst = '2017-03-07T12:00:00'
-    expect(await liquid.parseAndRender(src, ctx)).to.equal(dst)
+    return test('{{ time | date: "%Y-%m-%dT%H:%M:%S" }}', { time }, '2017-03-07T12:00:00')
   })
   it('should support manipulation', async function () {
-    const src = '{{ date | date: "%s" | minus : 604800  | date: "%Y-%m-%dT%H:%M:%S"}}'
-    const ctx = { date: new Date('2017-03-07T12:00:00') }
-    const dst = '2017-02-28T12:00:00'
-    expect(await liquid.parseAndRender(src, ctx)).to.equal(dst)
+    return test('{{ date | date: "%s" | minus : 604800  | date: "%Y-%m-%dT%H:%M:%S"}}',
+      { date: new Date('2017-03-07T12:00:00') },
+      '2017-02-28T12:00:00'
+    )
   })
 })
diff --git a/test/integration/builtin/filters/html.ts b/test/integration/builtin/filters/html.ts
index 0d3055950..fc0e605ff 100644
--- a/test/integration/builtin/filters/html.ts
+++ b/test/integration/builtin/filters/html.ts
@@ -10,7 +10,7 @@ describe('filters/html', function () {
       return test('{{ "Tetsuro Takara" | escape }}', 'Tetsuro Takara')
     })
     it('should escape function', function () {
-      return test('{{ func | escape }}', 'function () { }')
+      return test('{{ func | escape }}', { func: function () {} }, 'function () { }')
     })
     it('should escape undefined', function () {
       return test('{{ nonExistent.value | escape }}', '')
diff --git a/test/integration/builtin/filters/math.ts b/test/integration/builtin/filters/math.ts
index ed995812c..c14c72db5 100644
--- a/test/integration/builtin/filters/math.ts
+++ b/test/integration/builtin/filters/math.ts
@@ -1,13 +1,10 @@
 import { expect } from 'chai'
 import { test, liquid } from '../../../stub/render'
-import { Liquid } from '../../../../src/liquid'
 
 describe('filters/math', function () {
-  const l = 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 2 for arr[0]', () => test('{{ arr[0] | abs }}', { arr: [-2, 'a'] }, '2'))
     it('should return convert string', () => test('{{ "-3" | abs }}', '3'))
   })
   describe('at_least', function () {
@@ -60,10 +57,7 @@ describe('filters/math', function () {
       () => 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 variable', async () => {
-      const html = await l.parseAndRender('{{ 4 | plus: b }}', { b: 2 })
-      expect(html).to.equal('6')
-    })
+    it('should support variable', () => test('{{ 4 | plus: b }}', { b: 2 }, '6'))
   })
 
   describe('sort_natural', function () {
@@ -73,55 +67,36 @@ describe('filters/math', function () {
         'giraffe, octopus, Sally Snake, zebra'
       )
     })
-    it('should sort with specified property', async () => {
-      const src = '{{ students | sort_natural: "name" | map: "name" | join }}'
-      const students = [{ name: 'bob' }, { name: 'alice' }, { name: 'carol' }]
-      const html = await l.parseAndRender(src, { students })
-      expect(html).to.equal('alice bob carol')
-    })
-    it('should be stable', async () => {
-      const src = '{{ students | sort_natural: "age" | map: "name" | join }}'
-      const students = [
-        { name: 'bob', age: 1 },
-        { name: 'alice', age: 1 },
-        { name: 'carol', age: 1 }
-      ]
-      const html = await l.parseAndRender(src, { students })
-      expect(html).to.equal('bob alice carol')
-    })
-    it('should be stable when it comes to undefined props', async () => {
-      const src = '{{ students | sort_natural: "age" | map: "name" | join }}'
-      const students = [
-        { name: 'bob' },
-        { name: 'alice', age: 2 },
-        { name: 'amber' },
-        { name: 'watson' },
-        { name: 'michael' },
-        { name: 'charlie' }
-      ]
-      const html = await l.parseAndRender(src, { students })
-      expect(html).to.equal('alice bob amber watson michael charlie')
-    })
-    it('should tolerate undefined props', async () => {
-      const src = '{{ students | sort_natural: "age" | map: "name" | join }}'
-      const students = [
-        { name: 'bob' },
-        { name: 'alice', age: 2 },
-        { name: 'carol' }
-      ]
-      const html = await l.parseAndRender(src, { students })
-      expect(html).to.equal('alice bob carol')
-    })
-    it('should tolerate non array', async () => {
-      const src = '{{ students | sort_natural: "age" | map: "name" | join }}'
-      const html = await l.parseAndRender(src, { students: {} })
-      expect(html).to.equal('')
-    })
-    it('should tolerate falsy input', async () => {
-      const src = '{{ students | sort_natural: "age" | map: "name" | join }}'
-      const html = await l.parseAndRender(src, { students: undefined })
-      expect(html).to.equal('')
-    })
+    it('should sort with specified property', () => test(
+      '{{ students | sort_natural: "name" | map: "name" | join }}',
+      { students: [{ name: 'bob' }, { name: 'alice' }, { name: 'carol' }] },
+      'alice bob carol'
+    ))
+    it('should be stable', () => test(
+      '{{ students | sort_natural: "age" | map: "name" | join }}',
+      { students: [{ name: 'bob', age: 1 }, { name: 'alice', age: 1 }, { name: 'carol', age: 1 }] },
+      'bob alice carol'
+    ))
+    it('should be stable when it comes to undefined props', () => test(
+      '{{ students | sort_natural: "age" | map: "name" | join }}',
+      { students: [{ name: 'bob' }, { name: 'alice', age: 2 }, { name: 'amber' }, { name: 'watson' }, { name: 'michael' }, { name: 'charlie' }] },
+      'alice bob amber watson michael charlie'
+    ))
+    it('should tolerate undefined props', () => test(
+      '{{ students | sort_natural: "age" | map: "name" | join }}',
+      { students: [{ name: 'bob' }, { name: 'alice', age: 2 }, { name: 'carol' }] },
+      'alice bob carol'
+    ))
+    it('should tolerate non array', () => test(
+      '{{ students | sort_natural: "age" | map: "name" | join }}',
+      { students: {} },
+      ''
+    ))
+    it('should tolerate falsy input', () => test(
+      '{{ students | sort_natural: "age" | map: "name" | join }}',
+      { students: undefined },
+      ''
+    ))
   })
   describe('round', function () {
     it('should return "1" for 1.2', () => test('{{1.2|round}}', '1'))
diff --git a/test/integration/builtin/filters/string.ts b/test/integration/builtin/filters/string.ts
index 1c1acc7ce..29d0998b0 100644
--- a/test/integration/builtin/filters/string.ts
+++ b/test/integration/builtin/filters/string.ts
@@ -1,19 +1,14 @@
 import { test } from '../../../stub/render'
-import { Liquid } from '../../../../src/liquid'
 import { expect, use } from 'chai'
 import * as chaiAsPromised from 'chai-as-promised'
 
 use(chaiAsPromised)
 
 describe('filters/string', function () {
-  let liquid: Liquid
-  beforeEach(function () {
-    liquid = new Liquid()
-  })
   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 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/)
     })
@@ -25,7 +20,7 @@ describe('filters/string', function () {
   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 "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/)
     })
@@ -35,18 +30,9 @@ describe('filters/string', function () {
     it('should return "falseabc" for "abc", false', () => test('{{ "abc" | prepend: false }}', 'falseabc'))
   })
   describe('capitalize', function () {
-    it('should capitalize first', async () => {
-      const html = await liquid.parseAndRender('{{ "i am good" | capitalize }}')
-      expect(html).to.equal('I am good')
-    })
-    it('should return empty for nil', async () => {
-      const html = await liquid.parseAndRender('{{ nil | capitalize }}')
-      expect(html).to.equal('')
-    })
-    it('should return empty for undefined', async () => {
-      const html = await liquid.parseAndRender('{{ foo | capitalize }}')
-      expect(html).to.equal('')
-    })
+    it('should capitalize first', () => test('{{ "i am good" | capitalize }}', 'I am good'))
+    it('should return empty for nil', () => test('{{ nil | capitalize }}', ''))
+    it('should return empty for undefined', async () => test('{{ foo | capitalize }}', ''))
   })
   describe('concat', function () {
     it('should concat arrays', () => test(`
@@ -84,18 +70,13 @@ describe('filters/string', function () {
       `))
   })
   describe('downcase', function () {
-    it('should return "parker moore" for "Parker Moore"', async () => {
-      const html = await liquid.parseAndRender('{{ "Parker Moore" | downcase }}')
-      expect(html).to.equal('parker moore')
-    })
-    it('should return "apple" for "apple"', async () => {
-      const html = await liquid.parseAndRender('{{ "apple" | downcase }}')
-      expect(html).to.equal('apple')
-    })
-    it('should return empty for undefined', async () => {
-      const html = await liquid.parseAndRender('{{ foo | downcase }}')
-      expect(html).to.equal('')
-    })
+    it('should return "parker moore" for "Parker Moore"', () =>
+      test('{{ "Parker Moore" | downcase }}', 'parker moore')
+    )
+    it('should return "apple" for "apple"', () =>
+      test('{{ "apple" | downcase }}', 'apple')
+    )
+    it('should return empty for undefined', () => test('{{ foo | downcase }}', ''))
   })
   describe('split', function () {
     it('should support split/first', function () {
@@ -105,14 +86,8 @@ describe('filters/string', function () {
     })
   })
   describe('upcase', function () {
-    it('should support upcase', async () => {
-      const html = await liquid.parseAndRender('{{ "Parker Moore" | upcase }}')
-      expect(html).to.equal('PARKER MOORE')
-    })
-    it('should return empty for undefined', async () => {
-      const html = await liquid.parseAndRender('{{ foo | upcase }}')
-      expect(html).to.equal('')
-    })
+    it('should support upcase', () => test('{{ "Parker Moore" | upcase }}', 'PARKER MOORE'))
+    it('should return empty for undefined', () => test('{{ foo | upcase }}', ''))
   })
   it('should support lstrip', function () {
     const src = '{{ "          So much room for activities!          " | lstrip }}'
@@ -124,24 +99,15 @@ describe('filters/string', function () {
     'liquidmarkup.com/index.html')
   })
   describe('remove', function () {
-    it('should support remove', async () => {
-      const html = await liquid.parseAndRender('{{ "I strained to see the train through the rain" | remove: "rain" }}')
-      expect(html).to.equal('I sted to see the t through the ')
-    })
-    it('should return empty for undefined', async () => {
-      const html = await liquid.parseAndRender('{{ foo | remove: "rain" }}')
-      expect(html).to.equal('')
-    })
+    it('should support remove', () => test(
+      '{{ "I strained to see the train through the rain" | remove: "rain" }}',
+      'I sted to see the t through the '
+    ))
+    it('should return empty for undefined', () => test('{{ foo | remove: "rain" }}', ''))
   })
   describe('remove_first', function () {
-    it('should support remove_first', async () => {
-      const html = await liquid.parseAndRender('{{ "I strained to see the train through the rain" | remove_first: "rain" }}')
-      expect(html).to.equal('I sted to see the train through the rain')
-    })
-    it('should return empty for undefined', async () => {
-      const html = await liquid.parseAndRender('{{ foo | remove_first: "r" }}')
-      expect(html).to.equal('')
-    })
+    it('should support remove_first', () => test('{{ "I strained to see the train through the rain" | remove_first: "rain" }}', 'I sted to see the train through the rain'))
+    it('should return empty for undefined', () => test('{{ foo | remove_first: "r" }}', ''))
   })
   it('should support replace', function () {
     return test('{{ "Take my protein pills and put my helmet on" | replace: "my", "your" }}',
diff --git a/test/stub/render.ts b/test/stub/render.ts
index 10d7d72d2..997be0a61 100644
--- a/test/stub/render.ts
+++ b/test/stub/render.ts
@@ -3,25 +3,14 @@ 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 () {}, // eslint-disable-line
-  posts: [{ category: 'foo' }, { category: 'bar' }],
-  products: [
-    { title: 'Vacuum', type: 'living room' },
-    { title: 'Spatula', type: 'kitchen' },
-    { title: 'Television', type: 'living room' },
-    { title: 'Garlic press', type: 'kitchen' },
-    { title: 'Coffee mug', available: true },
-    { title: 'Limited edition sneakers', available: false },
-    { title: 'Boring sneakers', available: true }
-  ]
+export function render (src: string, ctx?: object) {
+  return liquid.parseAndRender(src, ctx)
 }
 
-export async function test (src: string, dst: string) {
-  const html = await liquid.parseAndRender(src, ctx)
-  return expect(html).to.equal(dst)
+export async function test (src: string, ctx: object | string, dst?: string) {
+  if (dst === undefined) {
+    dst = ctx as string
+    ctx = {}
+  }
+  return expect(await render(src, ctx as object)).to.equal(dst)
 }