Add DeletePendingReview endpoint

-   Added new API endpoint for deleting a pending review.
-   Wrote unit tests for the same.

Author: sahildua2305

github/pulls_reviews.go

@@ -103,6 +103,29 @@ func (s *PullRequestsService) GetReview(owner string, repo string, number int, r
 	return review, resp, err
 }
 
+// DeletePendingReview deletes the specified pull request pending review.
+//
+// GitHub API docs: https://developer.github.com/v3/pulls/reviews/#delete-a-pending-review
+func (s *PullRequestsService) DeletePendingReview(owner string, repo string, number int, reviewID int) (*PullRequestReview, *Response, error) {
+	u := fmt.Sprintf("repos/%v/%v/pulls/%d/reviews/%d", owner, repo, number, reviewID)
+
+	req, err := s.client.NewRequest("DELETE", u, nil)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	// TODO: remove custom Accept header when this API fully launches
+	req.Header.Set("Accept", mediaTypePullRequestReviewsPreview)
+
+	review := new(PullRequestReview)
+	resp, err := s.client.Do(req, review)
+	if err != nil {
+		return nil, resp, err
+	}
+
+	return review, resp, err
+}
+
 // ListReviewComments lists all the comments for the specified review.
 //
 // GitHub API docs: https://developer.github.com/v3/pulls/reviews/#get-a-single-reviews-comments

github/pulls_reviews_test.go

@@ -68,6 +68,32 @@ func TestPullRequestsService_GetReview_invalidOwner(t *testing.T) {
 	testURLParseError(t, err)
 }
 
+func TestPullRequestsService_DeletePendingReview(t *testing.T) {
+	setup()
+	defer teardown()
+
+	mux.HandleFunc("/repos/o/r/pulls/1/reviews/1", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "DELETE")
+		testHeader(t, r, "Accept", mediaTypePullRequestReviewsPreview)
+		fmt.Fprint(w, `{"id":1}`)
+	})
+
+	review, _, err := client.PullRequests.DeletePendingReview("o", "r", 1, 1)
+	if err != nil {
+		t.Errorf("PullRequests.DeletePendingReview returned error: %v", err)
+	}
+
+	want := &PullRequestReview{ID: Int(1)}
+	if !reflect.DeepEqual(review, want) {
+		t.Errorf("PullRequests.DeletePendingReview returned %+v, want %+v", review, want)
+	}
+}
+
+func TestPullRequestsService_DeletePendingReview_invalidOwner(t *testing.T) {
+	_, _, err := client.PullRequests.DeletePendingReview("%", "r", 1, 1)
+	testURLParseError(t, err)
+}
+
 func TestPullRequestsService_ListReviewComments(t *testing.T) {
 	setup()
 	defer teardown()