feature(repository): add listPullRequestCommits

lib/Repository.js

@@ -119,6 +119,17 @@ class Repository extends Requestable {
       return this._request('GET', `/repos/${this.__fullname}/pulls/${number}/files`, null, cb);
    }
 
+   /**
+    * List the commits of a specific pull request
+    * @see https://developer.github.com/v3/pulls/#list-commits-on-a-pull-request
+    * @param {number|string} number - the PR you wish to fetch
+    * @param {Requestable.callback} [cb] - will receive the list of commits from the API
+    * @return {Promise} - the promise for the http request
+    */
+   listPullRequestCommits(number, cb) {
+      return this._request('GET', `/repos/${this.__fullname}/pulls/${number}/commits`, null, cb);
+   }
+
    /**
     * Compare two branches/commits/repositories
     * @see https://developer.github.com/v3/repos/commits/#compare-two-commits

test/repository.spec.js

@@ -14,6 +14,7 @@ describe('Repository', function() {
    let imageBlob;
    const testRepoName = getTestRepoName();
    const v10SHA = '20fcff9129005d14cc97b9d59b8a3d37f4fb633b';
+   const testPRNumber = 153;
    const statusUrl =
     'https://api.github.com/repos/github-tools/github/statuses/20fcff9129005d14cc97b9d59b8a3d37f4fb633b';
 
@@ -479,10 +480,21 @@ describe('Repository', function() {
          }));
       });
 
+      it('should list pull request commits', function(done) {
+         const repo = github.getRepo('github-tools', 'github');
+         repo.listPullRequestCommits(testPRNumber, assertSuccessful(done, function(err, commits) {
+            expect(commits).to.be.an.array();
+            expect(commits).to.have.length(1);
+            expect(commits[0]).to.have.own('sha');
+
+            done();
+         }));
+      });
+
       it('should get pull requests on repo', function(done) {
          const repo = github.getRepo('github-tools', 'github');
 
-         repo.getPullRequest(153, assertSuccessful(done, function(err, pr) {
+         repo.getPullRequest(testPRNumber, assertSuccessful(done, function(err, pr) {
             expect(pr).to.have.own('title');
             expect(pr).to.have.own('body');
             expect(pr).to.have.own('url');