Fix aliased default options

Because extend does a shallow copy of object properties, some
options in interactable objects were aliased to objects in
the default objects. In some cases, setting options on one
interactable would bleed over to interactables made subsequently.

This commit adds a clone utility which is similar to extend,
but makes new objects instead of aliasing them. This allow the
newly added tests to pass.

src/Interactable.js

@@ -1,3 +1,4 @@
+const clone     = require('./utils/clone');
 const is        = require('./utils/is');
 const events    = require('./utils/events');
 const extend    = require('./utils/extend');
@@ -63,8 +64,9 @@ class Interactable {
       if (option in defaults[action]) {
         // if the option in the options arg is an object value
         if (is.object(options[option])) {
-          // duplicate the object
-          this.options[action][option] = extend(this.options[action][option] || {}, options[option]);
+          // duplicate the object and merge
+          this.options[action][option] = clone(this.options[action][option] || {});
+          extend(this.options[action][option], options[option]);
 
           if (is.object(defaults.perAction[option]) && 'enabled' in defaults.perAction[option]) {
             this.options[action][option].enabled = options[option].enabled === false? false : true;
@@ -294,14 +296,14 @@ class Interactable {
       options = {};
     }
 
-    this.options = extend({}, defaults.base);
+    this.options = clone(defaults.base);
 
-    const perActions = extend({}, defaults.perAction);
+    const perActions = clone(defaults.perAction);
 
     for (const actionName in actions.methodDict) {
       const methodName = actions.methodDict[actionName];
 
-      this.options[actionName] = extend({}, defaults[actionName]);
+      this.options[actionName] = clone(defaults[actionName]);
 
       this.setPerAction(actionName, perActions);
 

src/utils/clone.js

@@ -0,0 +1,13 @@
+const is = require('./is');
+
+module.exports = function clone (source) {
+  const dest = {};
+  for (const prop in source) {
+    if (is.object(source[prop])) {
+      dest[prop] = clone(source[prop]);
+    } else {
+      dest[prop] = source[prop];
+    }
+  }
+  return dest;
+};

tests/Interactable.js

@@ -0,0 +1,84 @@
+const test = require('./test');
+const d = require('./domator');
+
+const Interactable = require('../src/Interactable');
+const actions = require('../src/actions/base');
+
+test('Interactable copies and extends defaults', t => {
+  actions.methodDict.test = 'testize';
+  Interactable.prototype.testize = function (options) {
+    this.setPerAction('test', options);
+  };
+
+  const defaults = require('../src/defaultOptions');
+  defaults.test = {
+    fromDefault: { a: 1, b: 2 },
+    specified: { c: 1, d: 2 },
+  };
+
+  const specified = { specified: 'parent' };
+
+  const div = d('div');
+  const interactable = new Interactable(div, { test: specified });
+
+  t.deepEqual(interactable.options.test.specified, specified.specified,
+    'specified options are properly set');
+  t.deepEqual(interactable.options.test.fromDefault, defaults.test.fromDefault,
+    'default options are properly set');
+  t.notEqual(interactable.options.test.fromDefault, defaults.test.fromDefault,
+    'defaults are not aliased');
+
+  defaults.test.fromDefault.c = 3;
+  t.notOk('c' in interactable.options.test.fromDefault,
+    'modifying defaults does not affect constructed interactables');
+
+  // Undo global changes
+  delete actions.methodDict.test;
+  delete Interactable.prototype.testize;
+  delete defaults.test;
+
+  t.end();
+});
+
+test('Interactable copies and extends per action defaults', t => {
+  actions.methodDict.test = 'testize';
+  Interactable.prototype.testize = function (options) {
+    this.setPerAction('test', options);
+  };
+
+  const defaults = require('../src/defaultOptions');
+  defaults.perAction.testModifier = {
+    fromDefault: { a: 1, b: 2 },
+    specified: null,
+  };
+  defaults.test = { testModifier: defaults.perAction.testModifier };
+
+  const div = d('div');
+  const interactable = new Interactable(div, {});
+  interactable.testize({ testModifier: { specified: 'parent' } });
+
+  t.deepEqual(interactable.options.test, { testModifier: {
+    fromDefault: { a: 1, b: 2},
+    specified: 'parent',
+  }}, 'specified options are properly set');
+  t.deepEqual(
+    interactable.options.test.testModifier.fromDefault,
+    defaults.perAction.testModifier.fromDefault,
+    'default options are properly set');
+  t.notEqual(
+    interactable.options.test.testModifier.fromDefault,
+    defaults.perAction.testModifier.fromDefault,
+    'defaults are not aliased');
+
+  defaults.perAction.testModifier.fromDefault.c = 3;
+  t.notOk('c' in interactable.options.test.testModifier.fromDefault,
+    'modifying defaults does not affect constructed interactables');
+
+  // Undo global changes
+  delete actions.methodDict.test;
+  delete Interactable.prototype.test;
+  delete defaults.test;
+  delete defaults.perAction.testModifier;
+
+  t.end();
+});

tests/index.js

@@ -1,3 +1,4 @@
+require('./Interactable');
 require('./Interaction');
 
 // Legacy browser support