fix: copy basic plugin properties onto the wrapper (#4100)

Copy basic plugin properties to prevent breaking older basic plugins.

src/js/plugin.js

@@ -88,7 +88,8 @@ const markPluginAsActive = (player, name) => {
  * @returns {Function}
  *          A wrapper function for the given plugin.
  */
-const createBasicPlugin = (name, plugin) => function() {
+const createBasicPlugin = function(name, plugin) {
+  const basicPluginWrapper = function() {
     const instance = plugin.apply(this, arguments);
 
     markPluginAsActive(this, name);
@@ -101,6 +102,13 @@ const createBasicPlugin = (name, plugin) => function() {
     return instance;
   };
 
+  Object.keys(plugin).forEach(function(prop) {
+    basicPluginWrapper[prop] = plugin[prop];
+  });
+
+  return basicPluginWrapper;
+};
+
 /**
  * Takes a plugin sub-class and returns a factory function for generating
  * instances of it.

test/unit/plugin-basic.test.js

@@ -38,6 +38,13 @@ QUnit.test('setup', function(assert) {
   assert.deepEqual(this.basic.firstCall.args, [{foo: 'bar'}, 123], 'the plugin had the correct arguments');
   assert.ok(this.player.usingPlugin('basic'), 'the player now recognizes that the plugin was set up');
   assert.ok(this.player.hasPlugin('basic'), 'player has the plugin available');
+
+  this.player.basic({foo: 'bar'}, 123);
+  assert.strictEqual(this.basic.callCount, 2, 'the plugin was called twice');
+  assert.strictEqual(this.basic.firstCall.thisValue, this.player, 'the plugin `this` value was the player');
+  assert.deepEqual(this.basic.firstCall.args, [{foo: 'bar'}, 123], 'the plugin had the correct arguments');
+  assert.ok(this.player.usingPlugin('basic'), 'the player now recognizes that the plugin was set up');
+  assert.ok(this.player.hasPlugin('basic'), 'player has the plugin available');
 });
 
 QUnit.test('"pluginsetup" event', function(assert) {
@@ -58,3 +65,20 @@ QUnit.test('"pluginsetup" event', function(assert) {
     plugin: this.basic
   }, 'the event hash object is correct');
 });
+
+QUnit.test('properties are copied', function(assert) {
+  const foo = () => {};
+
+  foo.someProp = () => {};
+  foo.VERSION = '9.9.9';
+
+  Plugin.registerPlugin('foo', foo);
+
+  assert.strictEqual(this.player.foo.VERSION, foo.VERSION, 'properties are copied');
+  assert.strictEqual(this.player.foo.someProp, foo.someProp, 'properties are copied');
+
+  this.player.foo();
+
+  assert.strictEqual(this.player.foo.VERSION, foo.VERSION, 'properties still exist after init');
+  assert.strictEqual(this.player.foo.someProp, foo.someProp, 'properties still exist after init');
+});