xds testing: make header matching and path matching fail properly

tools/run_tests/run_xds_tests.py

@@ -991,8 +991,8 @@ def test_path_matching(gcp, original_backend_service, instance_group,
                 original_backend_instances + alternate_backend_instances,
                 _WAIT_FOR_STATS_SEC)
 
-            retry_count = 20
-            # Each attempt takes about 10 seconds, 20 retries is equivalent to 200
+            retry_count = 40
+            # Each attempt takes about 10 seconds, 40 retries is equivalent to 400
             # seconds timeout.
             for i in range(retry_count):
                 stats = get_client_stats(_NUM_TEST_RPCS, _WAIT_FOR_STATS_SEC)
@@ -1004,6 +1004,10 @@ def test_path_matching(gcp, original_backend_service, instance_group,
                 if compare_expected_instances(stats, expected_instances):
                     logger.info("success")
                     break
+                elif i == retry_count - 1:
+                    raise Exception(
+                        'timeout waiting for RPCs to the expected instances: %s'
+                        % expected_instances)
     finally:
         patch_url_map_backend_service(gcp, original_backend_service)
         patch_backend_service(gcp, alternate_backend_service, [])
@@ -1121,8 +1125,8 @@ def test_header_matching(gcp, original_backend_service, instance_group,
                 original_backend_instances + alternate_backend_instances,
                 _WAIT_FOR_STATS_SEC)
 
-            retry_count = 20
-            # Each attempt takes about 10 seconds, 10 retries is equivalent to 100
+            retry_count = 40
+            # Each attempt takes about 10 seconds, 40 retries is equivalent to 400
             # seconds timeout.
             for i in range(retry_count):
                 stats = get_client_stats(_NUM_TEST_RPCS, _WAIT_FOR_STATS_SEC)
@@ -1134,6 +1138,10 @@ def test_header_matching(gcp, original_backend_service, instance_group,
                 if compare_expected_instances(stats, expected_instances):
                     logger.info("success")
                     break
+                elif i == retry_count - 1:
+                    raise Exception(
+                        'timeout waiting for RPCs to the expected instances: %s'
+                        % expected_instances)
     finally:
         patch_url_map_backend_service(gcp, original_backend_service)
         patch_backend_service(gcp, alternate_backend_service, [])