diff --git a/package.json b/package.json
index 9c9568958b..e86c7e550e 100644
--- a/package.json
+++ b/package.json
@@ -10,7 +10,7 @@
     "unit": "mocha 'test/unit/**/*.ts'",
     "e2e": "npm run build && mocha 'test/e2e/**/*.ts'",
     "test": "npm run unit && npm run e2e",
-    "coverage-html": "nyc npm run unit && nyc report --reporter=html",
+    "coverage-html": "nyc --reporter=html npm run unit",
     "coverage-coveralls": "nyc npm run unit && nyc report --reporter=text-lcov | coveralls",
     "build": "rollup -c rollup.config.ts && ls -lh dist",
     "version": "npm run build && git add -A dist"
@@ -98,5 +98,6 @@
     "extension": [
       ".ts"
     ]
-  }
+  },
+  "dependencies": {}
 }
diff --git a/src/builtin/filters/string.ts b/src/builtin/filters/string.ts
index 0e8bf3eb95..d929af1961 100644
--- a/src/builtin/filters/string.ts
+++ b/src/builtin/filters/string.ts
@@ -16,15 +16,15 @@ export default {
   'split': (v: string, arg: string) => String(v).split(arg),
   'strip': (v: string) => String(v).trim(),
   'strip_newlines': (v: string) => String(v).replace(/\n/g, ''),
-  'truncate': (v: string, l: number = 16, o: string = '...') => {
+  'truncate': (v: string, l: number = 50, o: string = '...') => {
     v = String(v)
     if (v.length <= l) return v
     return v.substr(0, l - o.length) + o
   },
-  'truncatewords': (v: string, l: number = v.length, o: string = '...') => {
-    const arr = v.split(' ')
+  'truncatewords': (v: string, l: number = 15, o: string = '...') => {
+    const arr = v.split(/\s+/)
     let ret = arr.slice(0, l).join(' ')
-    if (arr.length > l) ret += o
+    if (arr.length >= l) ret += o
     return ret
   }
-} as {[key: string]: FilterImpl}
\ No newline at end of file
+} as {[key: string]: FilterImpl}
diff --git a/src/scope/scope.ts b/src/scope/scope.ts
index 31f3017f64..93dd5b6991 100644
--- a/src/scope/scope.ts
+++ b/src/scope/scope.ts
@@ -68,7 +68,7 @@ export default class Scope {
     }
     return null
   }
-  readProperty (obj: IContext, key: string) {
+  private readProperty (obj: IContext, key: string) {
     let val
     if (_.isNil(obj)) {
       val = undefined
diff --git a/test/unit/builtin/filters/string.ts b/test/unit/builtin/filters/string.ts
index a424187f09..fcb00f2cb7 100644
--- a/test/unit/builtin/filters/string.ts
+++ b/test/unit/builtin/filters/string.ts
@@ -136,8 +136,14 @@ describe('filters/string', function () {
     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...')
+    it('should truncate to "..." when len <= 3', function () {
+      return test('{{ "12345" | truncate: 2 }}', '...')
+    })
+    it('should not truncate if length is exactly len', function () {
+      return test('{{ "12345" | truncate: 5 }}', '12345')
+    })
+    it('should default to 50', function () {
+      return test('{{ "1234567890123456789012345678901234567890123456789abc" | truncate }}', '12345678901234567890123456789012345678901234567...')
     })
   })
   describe('truncatewords', function () {
@@ -157,5 +163,14 @@ describe('filters/string', function () {
       return test('{{ "Ground control to Major Tom." | truncatewords: 3, "" }}',
         'Ground control to')
     })
+    it('should allow multiple space chars between', function () {
+      return test('{{ "1 \t2  3 \n4" | truncatewords: 3 }}', '1 2 3...')
+    })
+    it('should show ellipsis if length is exactly len', function () {
+      return test('{{ "1 2 3" | truncatewords: 3 }}', '1 2 3...')
+    })
+    it('should default len to 15', function () {
+      return test('{{ "1 2 3 4 5 6 7 8 9 a b c d e f" | truncatewords }}', '1 2 3 4 5 6 7 8 9 a b c d e f...')
+    })
   })
 })
diff --git a/test/unit/fs/browser.ts b/test/unit/fs/browser.ts
index b36d8b3b91..06308d9b76 100644
--- a/test/unit/fs/browser.ts
+++ b/test/unit/fs/browser.ts
@@ -4,7 +4,6 @@ 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 () {
@@ -25,31 +24,38 @@ describe('fs/browser', 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')
+      expect(fs.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')
+      expect(fs.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')
+      expect(fs.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')
+      expect(fs.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')
+      expect(fs.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')
+      expect(fs.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')
+      expect(fs.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')
+      expect(fs.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')
+      expect(fs.resolve('https://example.com/views/', 'page.php', '.html')).to.equal('https://example.com/views/page.php')
+    })
+  })
+
+  describe('#exists()', () => {
+    it('should always return true', async function () {
+      const val = await fs.exists('/foo/bar')
+      expect(val).to.equal(true)
     })
   })
 
diff --git a/test/unit/fs/node.ts b/test/unit/fs/node.ts
index c7ec20212c..628ce977d7 100644
--- a/test/unit/fs/node.ts
+++ b/test/unit/fs/node.ts
@@ -2,17 +2,10 @@ 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')
@@ -27,21 +20,21 @@ describe('fs', function () {
   })
   describe('#exists', () => {
     it('should resolve as false if not exists', async () => {
-      const result = await fs.exists('/foo/foo.html')
+      const result = await fs.exists('/foo/bar')
       return expect(result).to.be.false
     })
     it('should resolve as true if exists', async () => {
-      const result = await fs.exists('/foo/bar.html')
+      const result = await fs.exists(__filename)
       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')
+      return expect(fs.readFile('/foo/bar')).to.rejectedWith('ENOENT')
     })
-    it('should throw when file not readable', function () {
-      return expect(fs.readFile('/un-readable.html')).to
-        .be.rejectedWith(/EACCES/)
+    it('should read content if exists', async function () {
+      const content = await fs.readFile(__filename)
+      return expect(content).to.contain('should read content if exists')
     })
   })
 })
diff --git a/test/unit/liquid/liquid-options.ts b/test/unit/liquid/liquid-options.ts
new file mode 100644
index 0000000000..6d1dd55afb
--- /dev/null
+++ b/test/unit/liquid/liquid-options.ts
@@ -0,0 +1,15 @@
+import { normalize } from 'src/liquid-options'
+import { expect } from 'chai'
+
+describe('LiquidOptions', function () {
+  describe('#normalize ()', function () {
+    it('should normalize string typed root array', function () {
+      const options = normalize({root: 'foo'})
+      expect(options.root).to.eql(['foo'])
+    })
+    it('should normalize null typed root as empty array', function () {
+      const options = normalize({root: null} as any)
+      expect(options.root).to.eql([])
+    })
+  })
+})
diff --git a/test/unit/liquid/liquid.ts b/test/unit/liquid/liquid.ts
index edf81a36d7..8dd1b12263 100644
--- a/test/unit/liquid/liquid.ts
+++ b/test/unit/liquid/liquid.ts
@@ -47,4 +47,14 @@ describe('Liquid', function () {
       })
     })
   })
+  describe('#renderFile', function () {
+    it('should throw with lookup list when file not exist', function () {
+      const engine = new Liquid({
+        root: ['/boo', '/root/'],
+        extname: '.html'
+      })
+      return expect(engine.renderFile('/not/exist.html')).to
+        .be.rejectedWith(/Failed to lookup "\/not\/exist.html" in "\/boo,\/root\/"/)
+    })
+  })
 })
diff --git a/test/unit/render/render.ts b/test/unit/render/render.ts
index 9f169114b1..ead6c07026 100644
--- a/test/unit/render/render.ts
+++ b/test/unit/render/render.ts
@@ -2,7 +2,7 @@ import { expect } from 'chai'
 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/Filter'
+import Filter from 'src/template/filter/filter'
 import Render from 'src/render/render'
 import HTML from 'src/template/html'
 
diff --git a/test/unit/scope/scope.ts b/test/unit/scope/scope.ts
index b24050927b..dd44283909 100644
--- a/test/unit/scope/scope.ts
+++ b/test/unit/scope/scope.ts
@@ -10,6 +10,7 @@ describe('scope', function () {
     ctx = {
       foo: 'zoo',
       one: 1,
+      zoo: { size: 4 },
       bar: {
         zoo: 'coo',
         'Mr.Smith': 'John',
@@ -133,6 +134,18 @@ describe('scope', function () {
     it('should return undefined when not exist', function () {
       expect(scope.get('foo.foo.foo')).to.be.undefined
     })
+    it('should return string length as size', function () {
+      expect(scope.get('foo.size')).to.equal(3)
+    })
+    it('should return array length as size', function () {
+      expect(scope.get('bar.arr.size')).to.equal(2)
+    })
+    it('should return size property if exists', function () {
+      expect(scope.get('zoo.size')).to.equal(4)
+    })
+    it('should return undefined if do not have size and length', function () {
+      expect(scope.get('one.size')).to.equal(undefined)
+    })
   })
 
   describe('#set', function () {
diff --git a/test/unit/util/underscore.ts b/test/unit/util/underscore.ts
index 585b01fa67..8e037d3e43 100644
--- a/test/unit/util/underscore.ts
+++ b/test/unit/util/underscore.ts
@@ -52,6 +52,10 @@ describe('util/underscore', function () {
     it('should return "" for undefined', function () {
       expect(_.stringify(undefined)).to.equal('')
     })
+    it('should use Object.prototype.toString if no toString method exists', function () {
+      const obj = { toString: undefined }
+      expect(_.stringify(obj)).to.equal('[object Object]')
+    })
     it('should return regex string for RegExp', function () {
       const reg = /foo/g
       expect(_.stringify(reg)).to.equal('/foo/g')