rewrite scrollspy unit tests

2 files changed, 1024 insertions, 0 deletions

diff --git a/js/src/scrollspy/scrollspy.js b/js/src/scrollspy/scrollspy.js
new file mode 100644
index 000000000..68c51f7d7
--- /dev/null
+++ b/js/src/scrollspy/scrollspy.js
@@ -0,0 +1,355 @@
+/**
+ * --------------------------------------------------------------------------
+ * Bootstrap (v4.3.1): scrollspy.js
+ * Licensed under MIT (https://github.com/twbs/bootstrap/blob/master/LICENSE)
+ * --------------------------------------------------------------------------
+ */
+
+import {
+  jQuery as $,
+  getSelectorFromElement,
+  getUID,
+  makeArray,
+  typeCheckConfig
+} from '../util/index'
+import Data from '../dom/data'
+import EventHandler from '../dom/event-handler'
+import Manipulator from '../dom/manipulator'
+import SelectorEngine from '../dom/selector-engine'
+
+/**
+ * ------------------------------------------------------------------------
+ * Constants
+ * ------------------------------------------------------------------------
+ */
+
+const NAME = 'scrollspy'
+const VERSION = '4.3.1'
+const DATA_KEY = 'bs.scrollspy'
+const EVENT_KEY = `.${DATA_KEY}`
+const DATA_API_KEY = '.data-api'
+
+const Default = {
+  offset: 10,
+  method: 'auto',
+  target: ''
+}
+
+const DefaultType = {
+  offset: 'number',
+  method: 'string',
+  target: '(string|element)'
+}
+
+const Event = {
+  ACTIVATE: `activate${EVENT_KEY}`,
+  SCROLL: `scroll${EVENT_KEY}`,
+  LOAD_DATA_API: `load${EVENT_KEY}${DATA_API_KEY}`
+}
+
+const ClassName = {
+  DROPDOWN_ITEM: 'dropdown-item',
+  ACTIVE: 'active'
+}
+
+const Selector = {
+  DATA_SPY: '[data-spy="scroll"]',
+  NAV_LIST_GROUP: '.nav, .list-group',
+  NAV_LINKS: '.nav-link',
+  NAV_ITEMS: '.nav-item',
+  LIST_ITEMS: '.list-group-item',
+  DROPDOWN: '.dropdown',
+  DROPDOWN_TOGGLE: '.dropdown-toggle'
+}
+
+const OffsetMethod = {
+  OFFSET: 'offset',
+  POSITION: 'position'
+}
+
+/**
+ * ------------------------------------------------------------------------
+ * Class Definition
+ * ------------------------------------------------------------------------
+ */
+
+class ScrollSpy {
+  constructor(element, config) {
+    this._element = element
+    this._scrollElement = element.tagName === 'BODY' ? window : element
+    this._config = this._getConfig(config)
+    this._selector = `${this._config.target} ${Selector.NAV_LINKS},` +
+                          `${this._config.target} ${Selector.LIST_ITEMS},` +
+                          `${this._config.target} .${ClassName.DROPDOWN_ITEM}`
+    this._offsets = []
+    this._targets = []
+    this._activeTarget = null
+    this._scrollHeight = 0
+
+    EventHandler.on(this._scrollElement, Event.SCROLL, event => this._process(event))
+
+    this.refresh()
+    this._process()
+
+    Data.setData(element, DATA_KEY, this)
+  }
+
+  // Getters
+
+  static get VERSION() {
+    return VERSION
+  }
+
+  static get Default() {
+    return Default
+  }
+
+  // Public
+
+  refresh() {
+    const autoMethod = this._scrollElement === this._scrollElement.window ?
+      OffsetMethod.OFFSET :
+      OffsetMethod.POSITION
+
+    const offsetMethod = this._config.method === 'auto' ?
+      autoMethod :
+      this._config.method
+
+    const offsetBase = offsetMethod === OffsetMethod.POSITION ?
+      this._getScrollTop() :
+      0
+
+    this._offsets = []
+    this._targets = []
+
+    this._scrollHeight = this._getScrollHeight()
+
+    const targets = makeArray(SelectorEngine.find(this._selector))
+
+    targets
+      .map(element => {
+        let target
+        const targetSelector = getSelectorFromElement(element)
+
+        if (targetSelector) {
+          target = SelectorEngine.findOne(targetSelector)
+        }
+
+        if (target) {
+          const targetBCR = target.getBoundingClientRect()
+          if (targetBCR.width || targetBCR.height) {
+            return [
+              Manipulator[offsetMethod](target).top + offsetBase,
+              targetSelector
+            ]
+          }
+        }
+
+        return null
+      })
+      .filter(item => item)
+      .sort((a, b) => a[0] - b[0])
+      .forEach(item => {
+        this._offsets.push(item[0])
+        this._targets.push(item[1])
+      })
+  }
+
+  dispose() {
+    Data.removeData(this._element, DATA_KEY)
+    EventHandler.off(this._scrollElement, EVENT_KEY)
+
+    this._element = null
+    this._scrollElement = null
+    this._config = null
+    this._selector = null
+    this._offsets = null
+    this._targets = null
+    this._activeTarget = null
+    this._scrollHeight = null
+  }
+
+  // Private
+
+  _getConfig(config) {
+    config = {
+      ...Default,
+      ...typeof config === 'object' && config ? config : {}
+    }
+
+    if (typeof config.target !== 'string') {
+      let { id } = config.target
+      if (!id) {
+        id = getUID(NAME)
+        config.target.id = id
+      }
+
+      config.target = `#${id}`
+    }
+
+    typeCheckConfig(NAME, config, DefaultType)
+
+    return config
+  }
+
+  _getScrollTop() {
+    return this._scrollElement === window ?
+      this._scrollElement.pageYOffset :
+      this._scrollElement.scrollTop
+  }
+
+  _getScrollHeight() {
+    return this._scrollElement.scrollHeight || Math.max(
+      document.body.scrollHeight,
+      document.documentElement.scrollHeight
+    )
+  }
+
+  _getOffsetHeight() {
+    return this._scrollElement === window ?
+      window.innerHeight :
+      this._scrollElement.getBoundingClientRect().height
+  }
+
+  _process() {
+    const scrollTop = this._getScrollTop() + this._config.offset
+    const scrollHeight = this._getScrollHeight()
+    const maxScroll = this._config.offset +
+      scrollHeight -
+      this._getOffsetHeight()
+
+    if (this._scrollHeight !== scrollHeight) {
+      this.refresh()
+    }
+
+    if (scrollTop >= maxScroll) {
+      const target = this._targets[this._targets.length - 1]
+
+      if (this._activeTarget !== target) {
+        this._activate(target)
+      }
+
+      return
+    }
+
+    if (this._activeTarget && scrollTop < this._offsets[0] && this._offsets[0] > 0) {
+      this._activeTarget = null
+      this._clear()
+      return
+    }
+
+    const offsetLength = this._offsets.length
+    for (let i = offsetLength; i--;) {
+      const isActiveTarget = this._activeTarget !== this._targets[i] &&
+          scrollTop >= this._offsets[i] &&
+          (typeof this._offsets[i + 1] === 'undefined' ||
+              scrollTop < this._offsets[i + 1])
+
+      if (isActiveTarget) {
+        this._activate(this._targets[i])
+      }
+    }
+  }
+
+  _activate(target) {
+    this._activeTarget = target
+
+    this._clear()
+
+    const queries = this._selector.split(',')
+      .map(selector => `${selector}[data-target="${target}"],${selector}[href="${target}"]`)
+
+    const link = SelectorEngine.findOne(queries.join(','))
+
+    if (link.classList.contains(ClassName.DROPDOWN_ITEM)) {
+      SelectorEngine
+        .findOne(Selector.DROPDOWN_TOGGLE, SelectorEngine.closest(link, Selector.DROPDOWN))
+        .classList.add(ClassName.ACTIVE)
+
+      link.classList.add(ClassName.ACTIVE)
+    } else {
+      // Set triggered link as active
+      link.classList.add(ClassName.ACTIVE)
+
+      SelectorEngine
+        .parents(link, Selector.NAV_LIST_GROUP)
+        .forEach(listGroup => {
+          // Set triggered links parents as active
+          // With both <ul> and <nav> markup a parent is the previous sibling of any nav ancestor
+          SelectorEngine.prev(listGroup, `${Selector.NAV_LINKS}, ${Selector.LIST_ITEMS}`)
+            .forEach(item => item.classList.add(ClassName.ACTIVE))
+
+          // Handle special case when .nav-link is inside .nav-item
+          SelectorEngine.prev(listGroup, Selector.NAV_ITEMS)
+            .forEach(navItem => {
+              SelectorEngine.children(navItem, Selector.NAV_LINKS)
+                .forEach(item => item.classList.add(ClassName.ACTIVE))
+            })
+        })
+    }
+
+    EventHandler.trigger(this._scrollElement, Event.ACTIVATE, {
+      relatedTarget: target
+    })
+  }
+
+  _clear() {
+    makeArray(SelectorEngine.find(this._selector))
+      .filter(node => node.classList.contains(ClassName.ACTIVE))
+      .forEach(node => node.classList.remove(ClassName.ACTIVE))
+  }
+
+  // Static
+
+  static _jQueryInterface(config) {
+    return this.each(function () {
+      let data = Data.getData(this, DATA_KEY)
+      const _config = typeof config === 'object' && config
+
+      if (!data) {
+        data = new ScrollSpy(this, _config)
+      }
+
+      if (typeof config === 'string') {
+        if (typeof data[config] === 'undefined') {
+          throw new TypeError(`No method named "${config}"`)
+        }
+
+        data[config]()
+      }
+    })
+  }
+
+  static _getInstance(element) {
+    return Data.getData(element, DATA_KEY)
+  }
+}
+
+/**
+ * ------------------------------------------------------------------------
+ * Data Api implementation
+ * ------------------------------------------------------------------------
+ */
+
+EventHandler.on(window, Event.LOAD_DATA_API, () => {
+  makeArray(SelectorEngine.find(Selector.DATA_SPY))
+    .forEach(spy => new ScrollSpy(spy, Manipulator.getDataAttributes(spy)))
+})
+
+/**
+ * ------------------------------------------------------------------------
+ * jQuery
+ * ------------------------------------------------------------------------
+ */
+/* istanbul ignore if */
+if (typeof $ !== 'undefined') {
+  const JQUERY_NO_CONFLICT = $.fn[NAME]
+  $.fn[NAME] = ScrollSpy._jQueryInterface
+  $.fn[NAME].Constructor = ScrollSpy
+  $.fn[NAME].noConflict = () => {
+    $.fn[NAME] = JQUERY_NO_CONFLICT
+    return ScrollSpy._jQueryInterface
+  }
+}
+
+export default ScrollSpy
diff --git a/js/src/scrollspy/scrollspy.spec.js b/js/src/scrollspy/scrollspy.spec.js
new file mode 100644
index 000000000..52b20ba09
--- /dev/null
+++ b/js/src/scrollspy/scrollspy.spec.js
@@ -0,0 +1,669 @@
+import ScrollSpy from './scrollspy'
+import Manipulator from '../dom/manipulator'
+import EventHandler from '../dom/event-handler'
+
+/** Test helpers */
+import { getFixture, clearFixture, createEvent, jQueryMock } from '../../tests/helpers/fixture'
+
+describe('ScrollSpy', () => {
+  let fixtureEl
+
+  const testElementIsActiveAfterScroll = ({ elementSelector, targetSelector, contentEl, scrollSpy, spy, cb }) => {
+    const element = fixtureEl.querySelector(elementSelector)
+    const target = fixtureEl.querySelector(targetSelector)
+
+    // add top padding to fix Chrome on Android failures
+    const paddingTop = 5
+    const scrollHeight = Math.ceil(contentEl.scrollTop + Manipulator.position(target).top) + paddingTop
+
+    function listener() {
+      expect(element.classList.contains('active')).toEqual(true)
+      contentEl.removeEventListener('scroll', listener)
+      expect(scrollSpy._process).toHaveBeenCalled()
+      spy.calls.reset()
+      cb()
+    }
+
+    contentEl.addEventListener('scroll', listener)
+    contentEl.scrollTop = scrollHeight
+  }
+
+  beforeAll(() => {
+    fixtureEl = getFixture()
+  })
+
+  afterEach(() => {
+    fixtureEl.style.display = 'none'
+    clearFixture()
+  })
+
+  describe('VERSION', () => {
+    it('should return plugin version', () => {
+      expect(ScrollSpy.VERSION).toEqual(jasmine.any(String))
+    })
+  })
+
+  describe('Default', () => {
+    it('should return plugin default config', () => {
+      expect(ScrollSpy.Default).toEqual(jasmine.any(Object))
+    })
+  })
+
+  describe('constructor', () => {
+    it('should generate an id when there is not one', () => {
+      fixtureEl.innerHTML = [
+        '<nav></nav>',
+        '<div class="content"></div>'
+      ].join('')
+
+      const navEl = fixtureEl.querySelector('nav')
+      const scrollSpy = new ScrollSpy(fixtureEl.querySelector('.content'), {
+        target: navEl
+      })
+
+      expect(scrollSpy).toBeDefined()
+      expect(navEl.getAttribute('id')).not.toEqual(null)
+    })
+
+    it('should not process element without target', () => {
+      fixtureEl.innerHTML = [
+        '<nav id="navigation" class="navbar">',
+        '  <ul class="navbar-nav">',
+        '    <li class="nav-item active"><a class="nav-link" id="one-link" href="#">One</a></li>',
+        '    <li class="nav-item"><a class="nav-link" id="two-link" href="#two">Two</a></li>',
+        '    <li class="nav-item"><a class="nav-link" id="three-link" href="#three">Three</a></li>',
+        '  </ul>',
+        '</nav>',
+        '<div id="content" style="height: 200px; overflow-y: auto;">',
+        ' <div id="two" style="height: 300px;"></div>',
+        ' <div id="three" style="height: 10px;"></div>',
+        '</div>'
+      ].join('')
+
+      fixtureEl.style.display = 'block'
+      const scrollSpy = new ScrollSpy(fixtureEl.querySelector('#content'), {
+        target: '#navigation'
+      })
+
+      expect(scrollSpy._targets.length).toEqual(2)
+    })
+
+    it('should only switch "active" class on current target', done => {
+      fixtureEl.innerHTML = [
+        '<div id="root" class="active" style="display: block">',
+        '  <div class="topbar">',
+        '    <div class="topbar-inner">',
+        '      <div class="container" id="ss-target">',
+        '        <ul class="nav">',
+        '          <li class="nav-item"><a href="#masthead">Overview</a></li>',
+        '          <li class="nav-item"><a href="#detail">Detail</a></li>',
+        '        </ul>',
+        '      </div>',
+        '    </div>',
+        '  </div>',
+        '  <div id="scrollspy-example" style="height: 100px; overflow: auto;">',
+        '    <div style="height: 200px;">',
+        '      <h4 id="masthead">Overview</h4>',
+        '      <p style="height: 200px;"></p>',
+        '    </div>',
+        '    <div style="height: 200px;">',
+        '      <h4 id="detail">Detail</h4>',
+        '      <p style="height: 200px;"></p>',
+        '    </div>',
+        '  </div>',
+        '</div>'
+      ].join('')
+
+      fixtureEl.style.display = 'block'
+      const scrollSpyEl = fixtureEl.querySelector('#scrollspy-example')
+      const rootEl = fixtureEl.querySelector('#root')
+      const scrollSpy = new ScrollSpy(scrollSpyEl, {
+        target: 'ss-target'
+      })
+
+      spyOn(scrollSpy, '_process').and.callThrough()
+
+      scrollSpyEl.addEventListener('scroll', () => {
+        expect(rootEl.classList.contains('active')).toEqual(true)
+        expect(scrollSpy._process).toHaveBeenCalled()
+        done()
+      })
+
+      scrollSpyEl.scrollTop = 350
+    })
+
+    it('should only switch "active" class on current target specified w element', done => {
+      fixtureEl.innerHTML = [
+        '<div id="root" class="active" style="display: block">',
+        '  <div class="topbar">',
+        '    <div class="topbar-inner">',
+        '      <div class="container" id="ss-target">',
+        '        <ul class="nav">',
+        '          <li class="nav-item"><a href="#masthead">Overview</a></li>',
+        '          <li class="nav-item"><a href="#detail">Detail</a></li>',
+        '        </ul>',
+        '      </div>',
+        '    </div>',
+        '  </div>',
+        '  <div id="scrollspy-example" style="height: 100px; overflow: auto;">',
+        '    <div style="height: 200px;">',
+        '      <h4 id="masthead">Overview</h4>',
+        '      <p style="height: 200px;"></p>',
+        '    </div>',
+        '    <div style="height: 200px;">',
+        '      <h4 id="detail">Detail</h4>',
+        '      <p style="height: 200px;"></p>',
+        '    </div>',
+        '  </div>',
+        '</div>'
+      ].join('')
+
+      const scrollSpyEl = fixtureEl.querySelector('#scrollspy-example')
+      const rootEl = fixtureEl.querySelector('#root')
+      const scrollSpy = new ScrollSpy(scrollSpyEl, {
+        target: fixtureEl.querySelector('#ss-target')
+      })
+
+      spyOn(scrollSpy, '_process').and.callThrough()
+
+      scrollSpyEl.addEventListener('scroll', () => {
+        expect(rootEl.classList.contains('active')).toEqual(true)
+        expect(scrollSpy._process).toHaveBeenCalled()
+        done()
+      })
+
+      fixtureEl.style.display = 'block'
+      scrollSpyEl.scrollTop = 350
+    })
+
+    it('should correctly select middle navigation option when large offset is used', done => {
+      fixtureEl.innerHTML = [
+        '<div id="header" style="height: 500px;"></div>',
+        '<nav id="navigation" class="navbar">',
+        ' <ul class="navbar-nav">',
+        '   <li class="nav-item active"><a class="nav-link" id="one-link" href="#one">One</a></li>',
+        '   <li class="nav-item"><a class="nav-link" id="two-link" href="#two">Two</a></li>',
+        '   <li class="nav-item"><a class="nav-link" id="three-link" href="#three">Three</a></li>',
+        ' </ul>',
+        '</nav>',
+        '<div id="content" style="height: 200px; overflow-y: auto;">',
+        ' <div id="one" style="height: 500px;"></div>',
+        ' <div id="two" style="height: 300px;"></div>',
+        ' <div id="three" style="height: 10px;"></div>',
+        '</div>'
+      ].join('')
+
+      fixtureEl.style.display = 'block'
+      const contentEl = fixtureEl.querySelector('#content')
+      const scrollSpy = new ScrollSpy(contentEl, {
+        target: '#navigation',
+        offset: Manipulator.position(contentEl).top
+      })
+
+      spyOn(scrollSpy, '_process').and.callThrough()
+
+      contentEl.addEventListener('scroll', () => {
+        expect(fixtureEl.querySelector('#one-link').classList.contains('active')).toEqual(false)
+        expect(fixtureEl.querySelector('#two-link').classList.contains('active')).toEqual(true)
+        expect(fixtureEl.querySelector('#three-link').classList.contains('active')).toEqual(false)
+        expect(scrollSpy._process).toHaveBeenCalled()
+        done()
+      })
+
+      contentEl.scrollTop = 550
+    })
+
+    it('should add the active class to the correct element', done => {
+      fixtureEl.innerHTML = [
+        '<nav class="navbar">',
+        '  <ul class="nav">',
+        '    <li class="nav-item"><a class="nav-link" id="a-1" href="#div-1">div 1</a></li>',
+        '    <li class="nav-item"><a class="nav-link" id="a-2" href="#div-2">div 2</a></li>',
+        '  </ul>',
+        '</nav>',
+        '<div class="content" style="overflow: auto; height: 50px">',
+        '  <div id="div-1" style="height: 100px; padding: 0; margin: 0">div 1</div>',
+        '  <div id="div-2" style="height: 200px; padding: 0; margin: 0">div 2</div>',
+        '</div>'
+      ].join('')
+
+      fixtureEl.style.display = 'block'
+      const contentEl = fixtureEl.querySelector('.content')
+      const scrollSpy = new ScrollSpy(contentEl, {
+        offset: 0,
+        target: '.navbar'
+      })
+      const spy = spyOn(scrollSpy, '_process').and.callThrough()
+
+      testElementIsActiveAfterScroll({
+        elementSelector: '#a-1',
+        targetSelector: '#div-1',
+        contentEl,
+        scrollSpy,
+        spy,
+        cb: () => {
+          testElementIsActiveAfterScroll({
+            elementSelector: '#a-2',
+            targetSelector: '#div-2',
+            contentEl,
+            scrollSpy,
+            spy,
+            cb: () => done()
+          })
+        }
+      })
+    })
+
+    it('should add the active class to the correct element (nav markup)', done => {
+      fixtureEl.innerHTML = [
+        '<nav class="navbar">',
+        '  <nav class="nav">',
+        '    <a class="nav-link" id="a-1" href="#div-1">div 1</a>',
+        '    <a class="nav-link" id="a-2" href="#div-2">div 2</a>',
+        '  </nav>',
+        '</nav>',
+        '<div class="content" style="overflow: auto; height: 50px">',
+        '  <div id="div-1" style="height: 100px; padding: 0; margin: 0">div 1</div>',
+        '  <div id="div-2" style="height: 200px; padding: 0; margin: 0">div 2</div>',
+        '</div>'
+      ].join('')
+
+      fixtureEl.style.display = 'block'
+      const contentEl = fixtureEl.querySelector('.content')
+      const scrollSpy = new ScrollSpy(contentEl, {
+        offset: 0,
+        target: '.navbar'
+      })
+      const spy = spyOn(scrollSpy, '_process').and.callThrough()
+
+      testElementIsActiveAfterScroll({
+        elementSelector: '#a-1',
+        targetSelector: '#div-1',
+        contentEl,
+        scrollSpy,
+        spy,
+        cb: () => {
+          testElementIsActiveAfterScroll({
+            elementSelector: '#a-2',
+            targetSelector: '#div-2',
+            contentEl,
+            scrollSpy,
+            spy,
+            cb: () => done()
+          })
+        }
+      })
+    })
+
+    it('should add the active class to the correct element (list-group markup)', done => {
+      fixtureEl.innerHTML = [
+        '<nav class="navbar">',
+        '  <div class="list-group">',
+        '    <a class="list-group-item" id="a-1" href="#div-1">div 1</a>',
+        '    <a class="list-group-item" id="a-2" href="#div-2">div 2</a>',
+        '  </div>',
+        '</nav>',
+        '<div class="content" style="overflow: auto; height: 50px">',
+        '  <div id="div-1" style="height: 100px; padding: 0; margin: 0">div 1</div>',
+        '  <div id="div-2" style="height: 200px; padding: 0; margin: 0">div 2</div>',
+        '</div>'
+      ].join('')
+
+      fixtureEl.style.display = 'block'
+      const contentEl = fixtureEl.querySelector('.content')
+      const scrollSpy = new ScrollSpy(contentEl, {
+        offset: 0,
+        target: '.navbar'
+      })
+      const spy = spyOn(scrollSpy, '_process').and.callThrough()
+
+      testElementIsActiveAfterScroll({
+        elementSelector: '#a-1',
+        targetSelector: '#div-1',
+        contentEl,
+        scrollSpy,
+        spy,
+        cb: () => {
+          testElementIsActiveAfterScroll({
+            elementSelector: '#a-2',
+            targetSelector: '#div-2',
+            contentEl,
+            scrollSpy,
+            spy,
+            cb: () => done()
+          })
+        }
+      })
+    })
+
+    it('should clear selection if above the first section', done => {
+      fixtureEl.innerHTML = [
+        '<div id="header" style="height: 500px;"></div>',
+        '<nav id="navigation" class="navbar">',
+        '  <ul class="navbar-nav">',
+        '    <li class="nav-item"><a id="one-link"   class="nav-link active" href="#one">One</a></li>',
+        '    <li class="nav-item"><a id="two-link"   class="nav-link" href="#two">Two</a></li>',
+        '    <li class="nav-item"><a id="three-link" class="nav-link" href="#three">Three</a></li>',
+        '  </ul>',
+        '</nav>',
+        '<div id="content" style="height: 200px; overflow-y: auto;">',
+        '  <div id="spacer" style="height: 100px;"></div>',
+        '  <div id="one" style="height: 100px;"></div>',
+        '  <div id="two" style="height: 100px;"></div>',
+        '  <div id="three" style="height: 100px;"></div>',
+        '  <div id="spacer" style="height: 100px;"></div>',
+        '</div>'
+      ].join('')
+
+      fixtureEl.style.display = 'block'
+
+      const contentEl = fixtureEl.querySelector('#content')
+      const scrollSpy = new ScrollSpy(contentEl, {
+        target: '#navigation',
+        offset: Manipulator.position(contentEl).top
+      })
+      const spy = spyOn(scrollSpy, '_process').and.callThrough()
+
+      let firstTime = true
+
+      contentEl.addEventListener('scroll', () => {
+        const active = fixtureEl.querySelector('.active')
+
+        expect(spy).toHaveBeenCalled()
+        spy.calls.reset()
+        if (firstTime) {
+          expect(fixtureEl.querySelectorAll('.active').length).toEqual(1)
+          expect(active.getAttribute('id')).toEqual('two-link')
+          firstTime = false
+          contentEl.scrollTop = 0
+        } else {
+          expect(active).toBeNull()
+          done()
+        }
+      })
+
+      contentEl.scrollTop = 201
+    })
+
+    it('should not clear selection if above the first section and first section is at the top', done => {
+      fixtureEl.innerHTML = [
+        '<div id="header" style="height: 500px;"></div>',
+        '<nav id="navigation" class="navbar">',
+        '  <ul class="navbar-nav">',
+        '    <li class="nav-item"><a id="one-link" class="nav-link active" href="#one">One</a></li>',
+        '    <li class="nav-item"><a id="two-link" class="nav-link" href="#two">Two</a></li>',
+        '    <li class="nav-item"><a id="three-link" class="nav-link" href="#three">Three</a></li>',
+        '  </ul>',
+        '</nav>',
+        '<div id="content" style="height: 200px; overflow-y: auto;">',
+        '  <div id="one" style="height: 100px;"></div>',
+        '  <div id="two" style="height: 100px;"></div>',
+        '  <div id="three" style="height: 100px;"></div>',
+        '  <div id="spacer" style="height: 100px;"></div>',
+        '</div>'
+      ].join('')
+
+      fixtureEl.style.display = 'block'
+
+      const negativeHeight = -10
+      const startOfSectionTwo = 101
+      const contentEl = fixtureEl.querySelector('#content')
+      const scrollSpy = new ScrollSpy(contentEl, {
+        target: '#navigation',
+        offset: contentEl.offsetTop
+      })
+      const spy = spyOn(scrollSpy, '_process').and.callThrough()
+
+      let firstTime = true
+
+      contentEl.addEventListener('scroll', () => {
+        const active = fixtureEl.querySelector('.active')
+
+        expect(spy).toHaveBeenCalled()
+        spy.calls.reset()
+        if (firstTime) {
+          expect(fixtureEl.querySelectorAll('.active').length).toEqual(1)
+          expect(active.getAttribute('id')).toEqual('two-link')
+          firstTime = false
+          contentEl.scrollTop = negativeHeight
+        } else {
+          expect(fixtureEl.querySelectorAll('.active').length).toEqual(1)
+          expect(active.getAttribute('id')).toEqual('one-link')
+          done()
+        }
+      })
+
+      contentEl.scrollTop = startOfSectionTwo
+    })
+
+    it('should correctly select navigation element on backward scrolling when each target section height is 100%', done => {
+      fixtureEl.innerHTML = [
+        '<nav class="navbar">',
+        '  <ul class="nav">',
+        '    <li class="nav-item"><a id="li-100-1" class="nav-link" href="#div-100-1">div 1</a></li>',
+        '    <li class="nav-item"><a id="li-100-2" class="nav-link" href="#div-100-2">div 2</a></li>',
+        '    <li class="nav-item"><a id="li-100-3" class="nav-link" href="#div-100-3">div 3</a></li>',
+        '    <li class="nav-item"><a id="li-100-4" class="nav-link" href="#div-100-4">div 4</a></li>',
+        '    <li class="nav-item"><a id="li-100-5" class="nav-link" href="#div-100-5">div 5</a></li>',
+        '  </ul>',
+        '</nav>',
+        '<div class="content" style="position: relative; overflow: auto; height: 100px">',
+        '  <div id="div-100-1" style="position: relative; height: 100%; padding: 0; margin: 0">div 1</div>',
+        '  <div id="div-100-2" style="position: relative; height: 100%; padding: 0; margin: 0">div 2</div>',
+        '  <div id="div-100-3" style="position: relative; height: 100%; padding: 0; margin: 0">div 3</div>',
+        '  <div id="div-100-4" style="position: relative; height: 100%; padding: 0; margin: 0">div 4</div>',
+        '  <div id="div-100-5" style="position: relative; height: 100%; padding: 0; margin: 0">div 5</div>',
+        '</div>'
+      ].join('')
+
+      fixtureEl.style.display = 'block'
+
+      const contentEl = fixtureEl.querySelector('.content')
+      const scrollSpy = new ScrollSpy(contentEl, {
+        offset: 0,
+        target: '.navbar'
+      })
+      const spy = spyOn(scrollSpy, '_process').and.callThrough()
+
+      testElementIsActiveAfterScroll({
+        elementSelector: '#li-100-5',
+        targetSelector: '#div-100-5',
+        scrollSpy,
+        spy,
+        contentEl,
+        cb() {
+          contentEl.scrollTop = 0
+          testElementIsActiveAfterScroll({
+            elementSelector: '#li-100-4',
+            targetSelector: '#div-100-4',
+            scrollSpy,
+            spy,
+            contentEl,
+            cb() {
+              contentEl.scrollTop = 0
+              testElementIsActiveAfterScroll({
+                elementSelector: '#li-100-3',
+                targetSelector: '#div-100-3',
+                scrollSpy,
+                spy,
+                contentEl,
+                cb() {
+                  contentEl.scrollTop = 0
+                  testElementIsActiveAfterScroll({
+                    elementSelector: '#li-100-2',
+                    targetSelector: '#div-100-2',
+                    scrollSpy,
+                    spy,
+                    contentEl,
+                    cb() {
+                      contentEl.scrollTop = 0
+                      testElementIsActiveAfterScroll({
+                        elementSelector: '#li-100-1',
+                        targetSelector: '#div-100-1',
+                        scrollSpy,
+                        spy,
+                        contentEl,
+                        cb: done
+                      })
+                    }
+                  })
+                }
+              })
+            }
+          })
+        }
+      })
+    })
+
+    it('should allow passed in option offset method: offset', () => {
+      fixtureEl.innerHTML = [
+        '<nav class="navbar">',
+        '  <ul class="nav">',
+        '    <li class="nav-item"><a id="li-jsm-1" class="nav-link" href="#div-jsm-1">div 1</a></li>',
+        '    <li class="nav-item"><a id="li-jsm-2" class="nav-link" href="#div-jsm-2">div 2</a></li>',
+        '    <li class="nav-item"><a id="li-jsm-3" class="nav-link" href="#div-jsm-3">div 3</a></li>',
+        '  </ul>',
+        '</nav>',
+        '<div class="content"  style="position: relative; overflow: auto; height: 100px">',
+        '  <div id="div-jsm-1" style="position: relative; height: 200px; padding: 0; margin: 0">div 1</div>',
+        '  <div id="div-jsm-2" style="position: relative; height: 150px; padding: 0; margin: 0">div 2</div>',
+        '  <div id="div-jsm-3" style="position: relative; height: 250px; padding: 0; margin: 0">div 3</div>',
+        '</div>'
+      ].join('')
+
+      fixtureEl.style.display = 'block'
+
+      const contentEl = fixtureEl.querySelector('.content')
+      const targetEl = fixtureEl.querySelector('#div-jsm-2')
+      const scrollSpy = new ScrollSpy(contentEl, {
+        target: '.navbar',
+        offset: 0,
+        method: 'offset'
+      })
+
+      expect(scrollSpy._offsets[1]).toEqual(Manipulator.offset(targetEl).top)
+      expect(scrollSpy._offsets[1]).not.toEqual(Manipulator.position(targetEl).top)
+    })
+
+    it('should allow passed in option offset method: position', () => {
+      fixtureEl.innerHTML = [
+        '<nav class="navbar">',
+        '  <ul class="nav">',
+        '    <li class="nav-item"><a id="li-jsm-1" class="nav-link" href="#div-jsm-1">div 1</a></li>',
+        '    <li class="nav-item"><a id="li-jsm-2" class="nav-link" href="#div-jsm-2">div 2</a></li>',
+        '    <li class="nav-item"><a id="li-jsm-3" class="nav-link" href="#div-jsm-3">div 3</a></li>',
+        '  </ul>',
+        '</nav>',
+        '<div class="content"  style="position: relative; overflow: auto; height: 100px">',
+        '  <div id="div-jsm-1" style="position: relative; height: 200px; padding: 0; margin: 0">div 1</div>',
+        '  <div id="div-jsm-2" style="position: relative; height: 150px; padding: 0; margin: 0">div 2</div>',
+        '  <div id="div-jsm-3" style="position: relative; height: 250px; padding: 0; margin: 0">div 3</div>',
+        '</div>'
+      ].join('')
+
+      fixtureEl.style.display = 'block'
+
+      const contentEl = fixtureEl.querySelector('.content')
+      const targetEl = fixtureEl.querySelector('#div-jsm-2')
+      const scrollSpy = new ScrollSpy(contentEl, {
+        target: '.navbar',
+        offset: 0,
+        method: 'position'
+      })
+
+      expect(scrollSpy._offsets[1]).not.toEqual(Manipulator.offset(targetEl).top)
+      expect(scrollSpy._offsets[1]).toEqual(Manipulator.position(targetEl).top)
+    })
+  })
+
+  describe('dispose', () => {
+    it('should dispose a scrollspy', () => {
+      spyOn(EventHandler, 'off')
+
+      const scrollSpy = new ScrollSpy(fixtureEl)
+
+      scrollSpy.dispose()
+      expect(EventHandler.off).toHaveBeenCalledWith(fixtureEl, '.bs.scrollspy')
+    })
+  })
+
+  describe('_jQueryInterface', () => {
+    it('should create a scrollspy', () => {
+      fixtureEl.innerHTML = '<div></div>'
+
+      const div = fixtureEl.querySelector('div')
+
+      jQueryMock.fn.scrollspy = ScrollSpy._jQueryInterface
+      jQueryMock.elements = [div]
+
+      jQueryMock.fn.scrollspy.call(jQueryMock)
+
+      expect(ScrollSpy._getInstance(div)).toBeDefined()
+    })
+
+    it('should not re create a scrollspy', () => {
+      fixtureEl.innerHTML = '<div></div>'
+
+      const div = fixtureEl.querySelector('div')
+      const scrollSpy = new ScrollSpy(div)
+
+      jQueryMock.fn.scrollspy = ScrollSpy._jQueryInterface
+      jQueryMock.elements = [div]
+
+      jQueryMock.fn.scrollspy.call(jQueryMock)
+
+      expect(ScrollSpy._getInstance(div)).toEqual(scrollSpy)
+    })
+
+    it('should call a scrollspy method', () => {
+      fixtureEl.innerHTML = '<div></div>'
+
+      const div = fixtureEl.querySelector('div')
+      const scrollSpy = new ScrollSpy(div)
+
+      spyOn(scrollSpy, 'refresh')
+
+      jQueryMock.fn.scrollspy = ScrollSpy._jQueryInterface
+      jQueryMock.elements = [div]
+
+      jQueryMock.fn.scrollspy.call(jQueryMock, 'refresh')
+
+      expect(ScrollSpy._getInstance(div)).toEqual(scrollSpy)
+      expect(scrollSpy.refresh).toHaveBeenCalled()
+    })
+
+    it('should throw error on undefined method', () => {
+      fixtureEl.innerHTML = '<div></div>'
+
+      const div = fixtureEl.querySelector('div')
+      const action = 'undefinedMethod'
+
+      jQueryMock.fn.scrollspy = ScrollSpy._jQueryInterface
+      jQueryMock.elements = [div]
+
+      try {
+        jQueryMock.fn.scrollspy.call(jQueryMock, action)
+      } catch (error) {
+        expect(error.message).toEqual(`No method named "${action}"`)
+      }
+    })
+  })
+
+  describe('_getInstance', () => {
+    it('should return null if there is no instance', () => {
+      expect(ScrollSpy._getInstance(fixtureEl)).toEqual(null)
+    })
+  })
+
+  describe('event handler', () => {
+    it('should create scrollspy on window load event', () => {
+      fixtureEl.innerHTML = '<div data-spy="scroll"></div>'
+
+      const scrollSpyEl = fixtureEl.querySelector('div')
+
+      window.dispatchEvent(createEvent('load'))
+
+      expect(ScrollSpy._getInstance(scrollSpyEl)).not.toBeNull()
+    })
+  })
+})