Add method for updating a pull request review (#1177)

Fixes: #1174.

Author: joshuabezaleel

github/pulls_reviews.go

@@ -189,6 +189,29 @@ func (s *PullRequestsService) CreateReview(ctx context.Context, owner, repo stri
 	return r, resp, nil
 }
 
+// UpdateReview updates the review summary on the specified pull request.
+//
+// GitHub API docs: https://developer.github.com/v3/pulls/reviews/#update-a-pull-request-review
+func (s *PullRequestsService) UpdateReview(ctx context.Context, owner, repo string, number int, reviewID int64, body string) (*PullRequestReview, *Response, error) {
+	opts := &struct {
+		Body string `json:"body"`
+	}{Body: body}
+	u := fmt.Sprintf("repos/%v/%v/pulls/%d/reviews/%d", owner, repo, number, reviewID)
+
+	req, err := s.client.NewRequest("PUT", u, opts)
+	if err != nil {
+		return nil, nil, err
+	}
+
+	review := &PullRequestReview{}
+	resp, err := s.client.Do(ctx, req, review)
+	if err != nil {
+		return nil, resp, err
+	}
+
+	return review, resp, nil
+}
+
 // SubmitReview submits a specified review on the specified pull request.
 //
 // TODO: Follow up with GitHub support about an issue with this method's

github/pulls_reviews_test.go

@@ -195,6 +195,26 @@ func TestPullRequestsService_CreateReview_invalidOwner(t *testing.T) {
 	testURLParseError(t, err)
 }
 
+func TestPullRequestsService_UpdateReview(t *testing.T) {
+	client, mux, _, teardown := setup()
+	defer teardown()
+
+	mux.HandleFunc("/repos/o/r/pulls/1/reviews/1", func(w http.ResponseWriter, r *http.Request) {
+		testMethod(t, r, "PUT")
+		fmt.Fprintf(w, `{"id":1}`)
+	})
+
+	got, _, err := client.PullRequests.UpdateReview(context.Background(), "o", "r", 1, 1, "updated_body")
+	if err != nil {
+		t.Errorf("PullRequests.UpdateReview returned error: %v", err)
+	}
+
+	want := &PullRequestReview{ID: Int64(1)}
+	if !reflect.DeepEqual(got, want) {
+		t.Errorf("PullRequests.UpdateReview = %+v, want %+v", got, want)
+	}
+}
+
 func TestPullRequestsService_SubmitReview(t *testing.T) {
 	client, mux, _, teardown := setup()
 	defer teardown()