test: follow redirects for login flows

Author: arnou

src/test/java/fr/cnieg/keycloak/providers/login/attribute/KeycloakLoginAttributeProviderTest.java

@@ -238,6 +238,7 @@ private LoginForm loadLoginForm(HttpSession session) {
                 "state", UUID.randomUUID().toString(),
                 "nonce", UUID.randomUUID().toString()
         ));
+        response = followRedirectIfNeeded(session, response);
         assertEquals(200, response.statusCode(), "Unable to load login page");
         return LoginForm.parse(response.getBody().asString());
     }
@@ -260,6 +261,7 @@ private LoginForm submitLoginForm(HttpSession session, LoginForm form, String us
 
     private ResetPasswordForm loadResetPasswordForm(HttpSession session, String url) {
         Response response = session.get(url, Collections.emptyMap());
+        response = followRedirectIfNeeded(session, response);
         assertEquals(200, response.statusCode(), "Unable to load reset password form");
         return ResetPasswordForm.parse(response.getBody().asString());
     }
@@ -293,6 +295,22 @@ private static String toAbsoluteUrl(String url) {
         return KEYCLOAK_CONTAINER.getAuthServerUrl() + url;
     }
 
+    private Response followRedirectIfNeeded(HttpSession session, Response response) {
+        if (response == null) {
+            return null;
+        }
+        if (!isRedirect(response.statusCode())) {
+            return response;
+        }
+        String location = response.getHeader("Location");
+        assertNotNull(location, "Redirect response missing Location header");
+        return session.get(toAbsoluteUrl(location), Collections.emptyMap());
+    }
+
+    private boolean isRedirect(int statusCode) {
+        return statusCode == 301 || statusCode == 302 || statusCode == 303 || statusCode == 307 || statusCode == 308;
+    }
+
     private record KeycloakEvent(String type, String error, Map<String, String> details) {
     }