[nft PATCH v2 2/2] tests/py: Support JSON validation

[Phil Sutter <phil@nwl.cc>]

Introduce a new flag -s/--schema to nft-test.py which enables validation
of any JSON input and output against our schema.

Make use of traceback module to get more details if validation fails.

Signed-off-by: Phil Sutter <phil@nwl.cc>
---
Changes since v1:
- Adjust commit message to changes from RFC.

Changes since RFC:
- Import builtin traceback module unconditionally
---
 tests/py/nft-test.py | 21 ++++++++++++++++++++-
 1 file changed, 20 insertions(+), 1 deletion(-)

diff --git a/tests/py/nft-test.py b/tests/py/nft-test.py
index 1c0afd0ec0eb3..d785f7ec74341 100755
--- a/tests/py/nft-test.py
+++ b/tests/py/nft-test.py
@@ -18,6 +18,7 @@ import os
 import argparse
 import signal
 import json
+import traceback
 
 TESTS_PATH = os.path.dirname(os.path.abspath(__file__))
 sys.path.insert(0, os.path.join(TESTS_PATH, '../../py/'))
@@ -687,6 +688,13 @@ def json_dump_normalize(json_string, human_readable = False):
     else:
         return json.dumps(json_obj, sort_keys = True)
 
+def json_validate(json_string):
+    json_obj = json.loads(json_string)
+    try:
+        nftables.json_validate(json_obj)
+    except Exception:
+        print_error("schema validation failed for input '%s'" % json_string)
+        print_error(traceback.format_exc())
 
 def rule_add(rule, filename, lineno, force_all_family_option, filename_path):
     '''
@@ -912,6 +920,9 @@ def rule_add(rule, filename, lineno, force_all_family_option, filename_path):
                     "expr": json.loads(json_input),
             }}}]})
 
+            if enable_json_schema:
+                json_validate(cmd)
+
             json_old = nftables.set_json_output(True)
             ret = execute_cmd(cmd, filename, lineno, payload_log, debug="netlink")
             nftables.set_json_output(json_old)
@@ -945,6 +956,9 @@ def rule_add(rule, filename, lineno, force_all_family_option, filename_path):
             nftables.set_numeric_proto_output(numeric_proto_old)
             nftables.set_stateless_output(stateless_old)
 
+            if enable_json_schema:
+                json_validate(json_output)
+
             json_output = json.loads(json_output)
             for item in json_output["nftables"]:
                 if "rule" in item:
@@ -1341,12 +1355,17 @@ def main():
                         dest='enable_json',
                         help='test JSON functionality as well')
 
+    parser.add_argument('-s', '--schema', action='store_true',
+                        dest='enable_schema',
+                        help='verify json input/output against schema')
+
     args = parser.parse_args()
-    global debug_option, need_fix_option, enable_json_option
+    global debug_option, need_fix_option, enable_json_option, enable_json_schema
     debug_option = args.debug
     need_fix_option = args.need_fix_line
     force_all_family_option = args.force_all_family
     enable_json_option = args.enable_json
+    enable_json_schema = args.enable_schema
     specific_file = False
 
     signal.signal(signal.SIGINT, signal_handler)
-- 
2.21.0