feature(gist): add comment-related features to Gist

* Add API to list all of a gist's comments
* Allow CRUD-ing comments on gists

Author: knsh14

lib/Gist.js

@@ -107,6 +107,63 @@ class Gist extends Requestable {
    isStarred(cb) {
       return this._request204or404(`/gists/${this.__id}/star`, null, cb);
    }
+
+
+
+   /**
+    * List the comments on a gist
+    * @see https://developer.github.com/v3/gists/comments/#list-comments-on-a-gist
+    * @param {Requestable.callback} [cb] - will receive the array of comments
+    * @return {Promise} - the promise for the http request
+    */
+   listComments(cb) {
+      return this._requestAllPages(`/gists/${this.__id}/comments`, null, cb);
+   }
+
+   /**
+    * Fetch a comment of the gist
+    * @see https://developer.github.com/v3/gists/comments/#get-a-single-comment
+    * @param {number} comment - the id of the comment
+    * @param {Requestable.callback} [cb] - will receive the comment
+    * @return {Promise} - the Promise for the http request
+    */
+   getComment(comment, cb) {
+      return this._request('GET', `/gists/${this.__id}/comments/${comment}`, null, cb);
+   }
+
+   /**
+    * Create Comment to a gist.
+    * @see https://developer.github.com/v3/gists/comments/#create-a-comment
+    * @param {string} comment - the comment to add
+    * @param {Requestable.callback} [cb] - the function that receives the API result
+    * @return {Promise} - the Promise for the http request
+    */
+   createComment(comment, cb) {
+      return this._request('POST', `/gists/${this.__id}/comments`, {body: comment}, cb);
+   }
+
+   /**
+    * Edit a Gist Comment
+    * @see https://developer.github.com/v3/gists/comments/#edit-a-comment
+    * @param {number} comment - the id of the comment
+    * @param {string} body - the new comment
+    * @param {Requestable.callback} [cb] - will receive the modified issue
+    * @return {Promise} - the promise for the http request
+    */
+   editComment(comment, body, cb) {
+      return this._request('PATCH', `/gists/${this.__id}/comments/${comment}`, {body: body}, cb);
+   }
+
+   /**
+    * Delete a comment of a gist.
+    * @see https://developer.github.com/v3/gists/comments/#delete-a-comment
+    * @param {number} comment - the id of the comment
+    * @param {Requestable.callback} [cb] - will receive true if the request succeeds
+    * @return {Promise} - the Promise for the http request
+    */
+   deleteComment(comment, cb) {
+      return this._request('DELETE', `/gists/${this.__id}/comments/${comment}`, null, cb);
+   }
 }
 
 module.exports = Gist;

test/gist.spec.js

@@ -9,6 +9,7 @@ describe('Gist', function() {
    let gist;
    let gistId;
    let github;
+   let commentId;
 
    before(function() {
       github = new Github({
@@ -64,6 +65,40 @@ describe('Gist', function() {
             }));
          }));
       });
+
+      it('should create a comment a gist', function(done) {
+         gist.createComment("Comment test", assertSuccessful(done, function(err, comment) {
+            expect(comment).to.have.own('body', 'Comment test');
+            commentId = comment.id
+            done();
+         }));
+      });
+
+      it('should list comments', function(done) {
+         gist.listComments(assertSuccessful(done, function(err, comments) {
+            expect(comments).to.be.an.array();
+            done();
+         }));
+      });
+
+      it('should get comment', function(done) {
+         gist.getComment(commentId, assertSuccessful(done, function(err, issue) {
+            expect(issue).to.have.own('id', commentId);
+            done();
+         }));
+      });
+
+      it('should edit comment', function(done) {
+         const newComment = 'new comment test';
+         gist.editComment(commentId, newComment, assertSuccessful(done, function(err, comment) {
+            expect(comment).to.have.own('body', newComment);
+            done();
+         }));
+      });
+
+      it('should delete comment', function(done) {
+         gist.deleteComment(commentId, assertSuccessful(done));
+      });
    });
 
    describe('deleting', function() {