feat(MeetingsAdapter): add joinMeeting() definition

src/MeetingsAdapter.js

@@ -118,6 +118,19 @@ export default class MeetingsAdapter extends WebexAdapter {
     return throwError(new Error('getMeeting(ID) must be defined in MeetingsAdapter'));
   }
 
+  /**
+   * Joins the meeting of the given ID.
+   * Joining a meeting is performed as a side-effect and this method does not
+   * return a value. Instead, joining a meeting should trigger getMeeting to
+   * emit a new updated Meeting object.
+   *
+   * @param {string} ID  ID of the meeting to join.
+   * @memberof MeetingsAdapter
+   */
+  joinMeeting(ID) {
+    throw new Error('joinMeeting(ID) must be defined in MeetingsAdapter');
+  }
+
   /**
    * Retrieves the local device media (video/audio) and adds them to the meeting
    * with the some default media settings.

src/MeetingsAdapter.test.js

@@ -45,6 +45,16 @@ describe('Meetings Adapter Interface', () => {
     });
   });
 
+  describe('joinMeeting()', () => {
+    test('errors because it needs to be defined', () => {
+      try {
+        meetingsAdapter.joinMeeting('meetingID');
+      } catch (error) {
+        expect(error.message).toBe('joinMeeting(ID) must be defined in MeetingsAdapter');
+      }
+    });
+  });
+
   describe('addLocalMedia()', () => {
     test('errors because it needs to be defined', () => {
       try {