test: add tests for deprecated function

The deprecated `.extend` method should not be called when the modules are imported.  The change in the next commit will allow users of the library to upgrade to video.js version 8 where the `.extend` method has been removed.

Issue silvermine#152

tests/ChromcastButton.test.js

@@ -0,0 +1,25 @@
+'use strict';
+
+var expect = require('expect.js');
+
+const chromecastButton = require('../src/js/components/ChromecastButton');
+
+class ButtonComponentStub {}
+
+describe('ChromecastButton', function() {
+   it('should not call videojs.extend', function() {
+      const videoJsSpy = {
+         extend: function() {
+            expect().fail('videojs.extends is deprecated');
+         },
+         getComponent: function() {
+            return ButtonComponentStub;
+         },
+         registerComponent: function(_, component) {
+            expect(component.prototype instanceof ButtonComponentStub).to.be(true);
+         },
+      };
+
+      chromecastButton(videoJsSpy);
+   });
+});

tests/ChromcastTech.test.js

@@ -0,0 +1,26 @@
+'use strict';
+
+var expect = require('expect.js');
+
+const chromecastTech = require('../src/js/tech/ChromecastTech');
+
+class TechComponentStub {
+}
+
+describe('ChromecastTech', function() {
+   it('should not call videojs.extend', function() {
+      const videoJsSpy = {
+         extend: function() {
+            expect().fail('videojs.extends is deprecated');
+         },
+         getComponent: function() {
+            return TechComponentStub;
+         },
+         registerTech: function(_, component) {
+            expect(component.prototype instanceof TechComponentStub).to.be(true);
+         },
+      };
+
+      chromecastTech(videoJsSpy);
+   });
+});