Added CheckRedirect support to Client.

Author: nuttmeister

client.go

@@ -769,6 +769,7 @@ func (c *Client) PostForm(url string, data url.Values) (*http.Response, error) {
 // shims in a *retryablehttp.Client for added retries.
 func (c *Client) StandardClient() *http.Client {
 	return &http.Client{
-		Transport: &RoundTripper{Client: c},
+		Transport:     &RoundTripper{Client: c},
+		CheckRedirect: c.HTTPClient.CheckRedirect,
 	}
 }

client_test.go

@@ -648,6 +648,68 @@ func TestClient_CheckRetryStop(t *testing.T) {
 	}
 }
 
+func TestClient_CheckRedirects(t *testing.T) {
+	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		w.Header().Add("Location", "/new/path")
+
+		switch r.URL.Path {
+		case "/301":
+			w.WriteHeader(301)
+		case "/302":
+			w.WriteHeader(302)
+		default:
+			w.WriteHeader(500)
+		}
+	}))
+	defer ts.Close()
+
+	client := NewClient()
+	client.HTTPClient.CheckRedirect = func(req *http.Request, via []*http.Request) error {
+		return http.ErrUseLastResponse
+	}
+	stdClient := client.StandardClient()
+
+	tests := []int{301, 302}
+
+	// Check that we get 301 and 302 responses.
+	for _, test := range tests {
+		resp, err := client.Get(fmt.Sprintf("%s/%d", ts.URL, test))
+		if err != nil {
+			t.Fatalf("unexpected error testing check redirect. %s", err.Error())
+		}
+		if resp.StatusCode != test {
+			t.Fatalf("expected status code %d but got %d", test, resp.StatusCode)
+		}
+
+		// Check with standard client as well.
+		resp, err = stdClient.Get(fmt.Sprintf("%s/%d", ts.URL, test))
+		if err != nil {
+			t.Fatalf("unexpected error testing check redirect. %s", err.Error())
+		}
+		if resp.StatusCode != test {
+			t.Fatalf("expected status code %d but got %d", test, resp.StatusCode)
+		}
+	}
+
+	// Check that we get errors when using default check redirect policy.
+	client = NewClient()
+	client.RetryMax = 0
+	stdClient = client.StandardClient()
+
+	for _, test := range tests {
+		_, err := client.Get(fmt.Sprintf("%s/%d", ts.URL, test))
+		if err == nil {
+			t.Fatalf("expected none nil error when testing default redirect behavior")
+		}
+
+		// Check with standard client as well.
+		_, err = stdClient.Get(fmt.Sprintf("%s/%d", ts.URL, test))
+		if err == nil {
+			t.Fatalf("expected none nil error when testing default redirect behavior")
+		}
+	}
+}
+
 func TestClient_Head(t *testing.T) {
 	// Mock server which always responds 200.
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {