Rolling forward https://codereview.chromium.org/1155683008/ which was

third_party/polymer/v0_8/components/iron-test-helpers/mock-interactions.js

-/**
- * @license
- * Copyright (c) 2014 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
- */
-
-(function(global) {
-  'use strict';
-
-  var HAS_NEW_MOUSE = (function() {
-    var has = false;
-    try {
-      has = Boolean(new MouseEvent('x'));
-    } catch (_) {}
-    return has;
-  })();
-
-  function middleOfNode(node) {
-    var bcr = node.getBoundingClientRect();
-    return {
-      y: bcr.top + (bcr.height / 2),
-      x: bcr.left + (bcr.width / 2)
-    };
-  }
-
-  function topLeftOfNode(node) {
-    var bcr = node.getBoundingClientRect();
-    return {
-      y: bcr.top,
-      x: bcr.left
-    };
-  }
-
-  function makeEvent(type, xy, node) {
-    var props = {
-      bubbles: true,
-      cancelable: true,
-      clientX: xy.x,
-      clientY: xy.y
-    };
-    var e;
-    var mousetype = type === 'tap' ? 'click' : 'mouse' + type;
-    if (HAS_NEW_MOUSE) {
-      e = new MouseEvent(mousetype, props);
-    } else {
-      e = document.createEvent('MouseEvent');
-      e.initMouseEvent(mousetype, props.bubbles, props.cancelable, null, null, 0, 0,
-        props.clientX, props.clientY, false, false, false, false, 0, null);
-    }
-    node.dispatchEvent(e);
-  }
-
-  function down(node, xy) {
-    xy = xy || middleOfNode(node);
-    makeEvent('down', xy, node);
-  }
-
-  function move(node, fromXY, toXY, steps) {
-    steps = steps || 5;
-    var dx = Math.round((fromXY.x - toXY.x) / steps);
-    var dy = Math.round((fromXY.y - toXY.y) / steps);
-    var xy = {
-      x: fromXY.x,
-      y: fromXY.y
-    };
-    for (var i = steps; i > 0; i--) {
-      makeEvent('move', xy, node);
-      xy.x += dx;
-      xy.y += dy;
-    }
-    makeEvent('move', {
-      x: toXY.x,
-      y: toXY.y
-    }, node);
-  }
-
-  function up(node, xy) {
-    xy = xy || middleOfNode(node);
-    makeEvent('up', xy, node);
-  }
-
-  function tap(node) {
-    var xy = middleOfNode(node);
-    down(node, xy);
-    up(node, xy);
-    makeEvent('tap', xy, node);
-  }
-
-  function focus(target) {
-    Polymer.Base.fire.call(target, 'focus');
-  }
-
-  function blur(target) {
-    Polymer.Base.fire.call(target, 'blur');
-  }
-
-  function downAndUp(target, callback) {
-    down(target);
-    Polymer.Base.async(function() {
-      up(target);
-      tap(target);
-
-      callback && callback();
-    });
-  }
-
-  function track(target, dx, dy, steps) {
-    dx = dx | 0;
-    dy = dy | 0;
-    steps = steps || 5;
-    down(target);
-    var xy = middleOfNode(target);
-    var xy2 = {
-      x: xy.x + dx,
-      y: xy.y + dy
-    };
-    move(target, xy, xy2, steps);
-    up(target, xy2);
-  }
-
-  function keyboardEventFor(type, keyCode) {
-    var event = new CustomEvent(type);
-
-    event.keyCode = keyCode;
-    event.code = keyCode;
-
-    return event;
-  }
-
-  function keyEventOn(target, type, keyCode) {
-    target.dispatchEvent(keyboardEventFor(type, keyCode));
-  }
-
-  function keyDownOn(target, keyCode) {
-    keyEventOn(target, 'keydown', keyCode);
-  }
-
-  function keyUpOn(target, keyCode) {
-    keyEventOn(target, 'keyup', keyCode);
-  }
-
-  function pressAndReleaseKeyOn(target, keyCode) {
-    keyDownOn(target, keyCode);
-    Polymer.Base.async(function() {
-      keyUpOn(target, keyCode);
-    }, 1);
-  }
-
-  function pressEnter(target) {
-    pressAndReleaseKeyOn(target, 13);
-  }
-
-  function pressSpace(target) {
-    pressAndReleaseKeyOn(target, 32);
-  }
-
-  global.MockInteractions = {
-    focus: focus,
-    blur: blur,
-    down: down,
-    up: up,
-    downAndUp: downAndUp,
-    tap: tap,
-    track: track,
-    pressAndReleaseKeyOn: pressAndReleaseKeyOn,
-    pressEnter: pressEnter,
-    pressSpace: pressSpace,
-    keyDownOn: keyDownOn,
-    keyUpOn: keyUpOn,
-    middleOfNode: middleOfNode,
-    topLeftOfNode: topLeftOfNode
-  };
-})(this);