From 71b70aaa46d80afa24f13b556b83417812333bfd Mon Sep 17 00:00:00 2001
From: Daniel Freedman <dfreedm@google.com>
Date: Thu, 9 Mar 2017 17:58:56 -0800
Subject: [PATCH] add lazy-upgrade tests

---
 lib/mixins/lazy-upgrade-mixin.html |  73 +++++++-
 test/runner.html                   |   3 +-
 test/unit/lazy-upgrade.html        | 268 +++++++++++++++++++++++++++++
 3 files changed, 339 insertions(+), 5 deletions(-)
 create mode 100644 test/unit/lazy-upgrade.html

diff --git a/lib/mixins/lazy-upgrade-mixin.html b/lib/mixins/lazy-upgrade-mixin.html
index 7c3a39c26c..8ec870b0aa 100644
--- a/lib/mixins/lazy-upgrade-mixin.html
+++ b/lib/mixins/lazy-upgrade-mixin.html
@@ -14,10 +14,29 @@
   (function(){
     'use strict';
 
+  /**
+   * Element class mixin that provides API for lazily upgrading Polymer Elements.
+   *
+   * This mixin can be used with the `disable-upgrade` attribute to lazily upgrade elements
+   * that are descendants of this element. This is useful for elements that need to display
+   * many elements.
+   *
+   * When upgrading elements, the mixin will upgrade as many as it can within the budget
+   * set by `_lazyUpgradeBudget`, which defaults to 16ms.
+   *
+   * When finished processing lazy-upgrade elements, this mixin will set `_lazyUpgrading`
+   * to false on the instance.
+   *
+   * @polymerMixin
+   * @memberof Polymer
+   * @summary Element class mixin that provides API for lazily upgrading Polymer elements
+   */
     Polymer.LazyUpgradeMixin = Polymer.dedupingMixin(function(base) {
 
       const LAZY_UPGRADE = 'lazy-upgrade';
       const DISABLE_UPGRADE = 'disable-upgrade';
+      const LAZY_UPGRADE_QUERY = `[${LAZY_UPGRADE}]`;
+      const LAZY_UPGRADE_BUDGET = 16;
 
       function sortCandidates(a, b) {
         let orderA = parseInt(a.getAttribute(LAZY_UPGRADE), 10) || 0;
@@ -26,7 +45,7 @@
       }
 
       function findCandidates(root) {
-        let candidates = Array.from(root.querySelectorAll(`[${LAZY_UPGRADE}]`));
+        let candidates = Array.from(root.querySelectorAll(LAZY_UPGRADE_QUERY));
         candidates.sort(sortCandidates);
         return candidates;
       }
@@ -39,25 +58,71 @@
         node.removeAttribute(LAZY_UPGRADE);
       }
 
+      function eventInCurrentScope(scope, event) {
+        return event.target === event.composedPath()[0];
+      }
+
+      /** @polymerMixinClass */
       return class LazyUpgrade extends base {
+        // add a configurable
+        static get properties() {
+          return {
+            /**
+             * Instance-level property for configuring the frame budget for lazy-upgrading elements.
+             * Defaults to 16ms
+             */
+            _lazyUpgradeBudget: {
+              type: Number,
+              value: LAZY_UPGRADE_BUDGET
+            },
+            /**
+             * Instance-level property that is shows when the element is lazy-upgrading elements
+             */
+            _lazyUpgrading: {
+              type: Boolean
+            }
+          }
+        }
+
         ready() {
           super.ready();
-          this.__lazyUpgradeDeadline = 16;
+          // check for dom-repeat and dom-if elements stamping lazy-upgrade nodes
+          this.addEventListener('dom-change', (ev) => {
+            if (!eventInCurrentScope(this, ev)) {
+              return;
+            }
+            let root = ev.composedPath()[0].parentNode;
+            let candidates = findCandidates(root);
+            for (let i = 0; i < candidates.length; i++) {
+              let c = candidates[i];
+              if (this.__lazyUpgradeQueue.indexOf(c) === -1) {
+                this.__lazyUpgradeQueue.push(c);
+              }
+            }
+            if (candidates.length && !this._lazyUpgrading) {
+              this._lazyUpgrading = true;
+              this.__lazyUpgrade();
+            }
+          });
+          this._lazyUpgrading = true;
           this.__lazyUpgradeQueue = findCandidates(this.shadowRoot || this);
           this.__lazyUpgrade();
         }
 
+        /**
+         * @private
+         */
         __lazyUpgrade() {
           if (this.__lazyUpgradeQueue.length) {
             Polymer.RenderStatus.afterNextRender(this, () => {
-              const deadline = performance.now() + this.__lazyUpgradeDeadline;
+              const deadline = performance.now() + this._lazyUpgradeBudget;
               while (this.__lazyUpgradeQueue.length && (performance.now() < deadline)) {
                 upgradeNode(this.__lazyUpgradeQueue.shift());
               }
               this.__lazyUpgrade();
             });
           } else {
-            this.dispatchEvent(new Event('lazy-upgrade-finished'));
+            this._lazyUpgrading = false;
           }
         }
       }
diff --git a/test/runner.html b/test/runner.html
index 86c18d4d2c..e84a0b9ca9 100644
--- a/test/runner.html
+++ b/test/runner.html
@@ -69,7 +69,8 @@
       'unit/mixin-utils.html',
       'unit/mixin-behaviors.html',
       'unit/render-status.html',
-      'unit/disable-upgrade.html'
+      'unit/disable-upgrade.html',
+      'unit/lazy-upgrade.html'
     ];
 
     // http://eddmann.com/posts/cartesian-product-in-javascript/
diff --git a/test/unit/lazy-upgrade.html b/test/unit/lazy-upgrade.html
new file mode 100644
index 0000000000..fe81561443
--- /dev/null
+++ b/test/unit/lazy-upgrade.html
@@ -0,0 +1,268 @@
+<!doctype html>
+<!--
+@license
+Copyright (c) 2017 The Polymer Project Authors. All rights reserved.
+This code may only be used under the BSD style license found at http://polymer.github.io/LICENSE.txt
+The complete set of authors may be found at http://polymer.github.io/AUTHORS.txt
+The complete set of contributors may be found at http://polymer.github.io/CONTRIBUTORS.txt
+Code distributed by Google as part of the polymer project is also
+subject to an additional IP rights grant found at http://polymer.github.io/PATENTS.txt
+-->
+<meta charset="utf-8">
+<script src="../../../webcomponentsjs/webcomponents-loader.js"></script>
+<script src="../../../web-component-tester/browser.js"></script>
+<link rel="import" href="../../polymer-element.html">
+<link rel="import" href="../../lib/elements/dom-if.html">
+<link rel="import" href="../../lib/mixins/lazy-upgrade-mixin.html">
+<link rel="import" href="../../lib/utils/async.html">
+<link rel="import" href="../../lib/utils/debounce.html">
+
+<script>
+  let Loaded = new Promise((resolve) => {
+    addEventListener('WebComponentsReady', () => {resolve()});
+  });
+  Loaded.then(function() {
+    let async = Polymer.Async.timeOut.after(150);
+    window.LazyParentMixin = class LazyParent extends Polymer.LazyUpgradeMixin(Polymer.Element) {
+      static get observers() {
+        return ['lazyUpgradingChanged(_lazyUpgrading)']
+      }
+      connectedCallback() {
+        this.upgradedChildren = [];
+        this.addEventListener('rendered', (e) => {
+          this.upgradedChildren.push(e.composedPath()[0]);
+        });
+        super.connectedCallback();
+      }
+      lazyUpgradingChanged() {
+        this.__lazyDebouncer = Polymer.Debouncer.debounce(this.__lazyDebouncer, async, () => {
+          this.dispatchEvent(new Event('lazy-upgrade-finished'));
+        });
+      }
+    }
+  });
+</script>
+
+<dom-module id="lazy-child">
+  <template>
+    <style>
+      :host(:not([disable-upgrade])) {
+        display: block;
+        border: 2px solid blue;
+        height: 20px;
+      }
+    </style>
+  </template>
+  <script>
+    Loaded.then(function() {
+      class LazyChild extends Polymer.Element {
+        static get is() {return 'lazy-child'}
+        ready() {
+          super.ready();
+          this.dispatchEvent(new Event('rendered', {bubbles: true, composed: true}));
+        }
+      }
+      customElements.define('lazy-child', LazyChild);
+    });
+  </script>
+</dom-module>
+
+<dom-module id="lazy-upgrade-shadow">
+  <template>
+    <lazy-child id="one" disable-upgrade lazy-upgrade></lazy-child>
+    <lazy-child id="two" disable-upgrade lazy-upgrade="1"></lazy-child>
+    <lazy-child id="three"></lazy-child>
+    <dom-if lazy-upgrade="1">
+      <lazy-child id="four" disable-upgrade lazy-upgrade></lazy-child>
+    </dom-if>
+    <lazy-child id="five" disable-upgrade></lazy-child>
+    <dom-if lazy-upgrade>
+      <lazy-child id="six"></lazy-child>
+    </dom-if>
+  </template>
+  <script>
+    Loaded.then(function() {
+      customElements.define('lazy-upgrade-shadow', class extends window.LazyParentMixin {
+        static get is() { return 'lazy-upgrade-shadow' }
+      });
+    });
+  </script>
+</dom-module>
+
+<dom-module id="lazy-parent">
+  <script>
+    Loaded.then(function() {
+      customElements.define('lazy-parent', class extends window.LazyParentMixin {});
+    });
+  </script>
+</dom-module>
+
+<template id="only-lazy-upgrade">
+  <dom-if>
+    <template>
+      <lazy-child id="one"></lazy-child>
+    </template>
+  </dom-if>
+  <dom-if lazy-upgrade>
+    <template>
+      <lazy-child id="two"></lazy-child>
+    </template>
+  </dom-if>
+  <lazy-child id="three" disable-upgrade></lazy-child>
+  <lazy-child id="four" disable-upgrade lazy-upgrade></lazy-child>
+  <dom-if lazy-upgrade>
+    <template>
+      <lazy-child id="five" disable-upgrade></lazy-child>
+      <lazy-child id="six" disable-upgrade lazy-upgrade></lazy-child>
+    </template>
+  </dom-if>
+</template>
+
+<template id="critical">
+  <lazy-child id="lazy-one" disable-upgrade lazy-upgrade></lazy-child>
+  <lazy-child id="critical"></lazy-child>
+  <lazy-child id="lazy-two" disable-upgrade lazy-upgrade></lazy-child>
+</template>
+
+<template id="ordered">
+  <lazy-child id="one" disable-upgrade lazy-upgrade="3"></lazy-child>
+  <lazy-child id="two" disable-upgrade lazy-upgrade="2"></lazy-child>
+  <lazy-child id="three" disable-upgrade lazy-upgrade="1"></lazy-child>
+  <lazy-child id="four" disable-upgrade lazy-upgrade></lazy-child>
+  <lazy-child id="five" disable-upgrade lazy-upgrade="2"></lazy-child>
+</template>
+
+<dom-module id="no-upgrade-shadow">
+  <template>
+    <lazy-child id="one" disable-upgrade lazy-upgrade></lazy-child>
+    <dom-if if>
+      <template>
+        <lazy-child id="two" disable-upgrade lazy-upgrade></lazy-child>
+      </template>
+    </dom-if>
+  </template>
+</dom-module>
+<script>
+  Loaded.then(() => {
+    customElements.define('no-upgrade-shadow', class extends Polymer.Element {
+      static get is() { return 'no-upgrade-shadow' }
+    });
+  });
+</script>
+
+<template id="scoped">
+  <no-upgrade-shadow></no-upgrade-shadow>
+  <lazy-child id="three" disable-upgrade lazy-upgrade></lazy-child>
+</template>
+
+<script>
+  suite('Lazy Upgrade Mixin', () => {
+    function assertUpgraded(node, expected) {
+      let disabled = node.hasAttribute('disable-upgrade');
+      assert.notEqual(disabled, expected, 'upgrade status was not expected');
+    }
+
+    function assertRendered(node, expected) {
+      let border = getComputedStyle(node).getPropertyValue('border-top-width');
+      assert.equal(border, expected ? '2px' : '0px', 'render status was not expected');
+    }
+
+    test('fires "lazy-upgrade-finished" event when done', (done) => {
+      let el = document.createElement('lazy-parent');
+      el.addEventListener('lazy-upgrade-finished', () => {
+        document.body.removeChild(el)
+        done();
+      });
+      document.body.appendChild(el);
+    });
+
+    test('Lazy Upgrading shows critical section first, lazy elements later', (done) => {
+      let template = document.querySelector('template#critical');
+      let el = document.createElement('lazy-parent');
+      el.appendChild(document.importNode(template.content, true));
+      let children = el.querySelectorAll('lazy-child');
+      el.addEventListener('lazy-upgrade-finished', () => {
+        for (let i = 0; i < children.length; i++) {
+          assertUpgraded(children[i], true);
+        }
+        el.parentNode.removeChild(el);
+        done();
+      })
+      document.body.appendChild(el);
+      assertUpgraded(children[0], false);
+      assertUpgraded(children[1], true);
+      assertUpgraded(children[2], false);
+    });
+
+    test('Lazy Upgrading activates elements with lazy-upgrade attribute', (done) => {
+      let template = document.querySelector('template#only-lazy-upgrade');
+      let el = document.createElement('lazy-parent');
+      el.appendChild(document.importNode(template.content, true));
+      el.addEventListener('lazy-upgrade-finished', () => {
+        let children = el.querySelectorAll('lazy-child');
+        assert.equal(children.length, 5);
+        assertRendered(children[0], true);
+        assertRendered(children[1], false);
+        assertRendered(children[2], true);
+        assertRendered(children[3], false);
+        assertRendered(children[4], true);
+        document.body.removeChild(el);
+        done();
+      });
+      document.body.appendChild(el);
+    });
+
+    test('Lazy upgrading respects ordering', (done) => {
+      let template = document.querySelector('template#ordered');
+      let el = document.createElement('lazy-parent');
+      el.appendChild(document.importNode(template.content, true));
+      el.addEventListener('lazy-upgrade-finished', () => {
+        let expected = [
+          "four",
+          "three",
+          "two",
+          "five",
+          "one"
+        ];
+        document.body.removeChild(el);
+        assert.deepEqual(el.upgradedChildren.map(n => n.id), expected);
+        done();
+      });
+      document.body.appendChild(el);
+    });
+
+    test('Shadow DOM works the same', (done) => {
+      let el = document.createElement('lazy-upgrade-shadow');
+      el.addEventListener('lazy-upgrade-finished', () => {
+        let children = el.shadowRoot.querySelectorAll('lazy-child');
+        assert.equal(children.length, 6);
+        let expected = [
+          "three",
+          "six",
+          "one",
+          "four",
+          "two"
+        ];
+        assert.deepEqual(el.upgradedChildren.map(n => n.id), expected);
+        document.body.removeChild(el);
+        done();
+      });
+      document.body.appendChild(el);
+    });
+
+    test('Candidates are only found in the same scope', (done) => {
+      let template = document.querySelector('template#scoped');
+      let el = document.createElement('lazy-parent');
+      el.addEventListener('lazy-upgrade-finished', () => {
+        let expected = [
+          "three"
+        ];
+        assert.deepEqual(el.upgradedChildren.map(n => n.id), expected);
+        document.body.removeChild(el);
+        done();
+      });
+      el.appendChild(document.importNode(template.content, true));
+      document.body.appendChild(el);
+    });
+  })
+</script>
\ No newline at end of file