Add karma testing framework and some basic tests

test/spec/.eslintrc

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+{
+  "env": {
+    "mocha": true
+  }
+}

test/spec/lib/api-item.js

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+'use strict';
+
+var assert = require('chai').assert;
+var ApiItem = require('../../../src/scripts/lib/api-item');
+var fixture = require('../../fixture');
+var items = require('../../../src/scripts/lib/items');
+
+/**
+ * @param {Object} object
+ * @param {Array} properties
+ */
+function checkReadOnly(object, properties) {
+  properties.forEach(function(property) {
+    assert.strictEqual(
+      Object.getOwnPropertyDescriptor(object, property).writable,
+      false
+    );
+  });
+}
+
+describe('ApiItem', function() {
+  it('defines read-only properties', function() {
+    var properties = [
+      'id',
+      'appKey',
+      'config',
+      '$element',
+      '$manipulatorTarget',
+      'on',
+      'one',
+      'off',
+      'trigger',
+      'initialize'
+    ];
+    var apiItem = new ApiItem(fixture('input'));
+    checkReadOnly(apiItem, properties);
+  });
+
+  it('attaches the manipulator methods', function() {
+    Object.keys(items).forEach(function(itemName) {
+      var apiItem = new ApiItem(fixture(itemName));
+      var manipulator = items[itemName].manipulator;
+      checkReadOnly(apiItem, Object.keys(manipulator));
+    });
+  });
+});