[nft PATCH RFC 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.

If validation was requested on command line, try to import traceback
module. Upon validation errors, this provides more insight into what
went wrong. If unavailable, simply continue without it.

Signed-off-by: Phil Sutter <phil@nwl.cc>
---
 tests/py/nft-test.py | 29 ++++++++++++++++++++++++++++-
 1 file changed, 28 insertions(+), 1 deletion(-)

diff --git a/tests/py/nft-test.py b/tests/py/nft-test.py
index 1c0afd0ec0eb3..bc038629befd3 100755
--- a/tests/py/nft-test.py
+++ b/tests/py/nft-test.py
@@ -687,6 +687,14 @@ 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)
+        if not traceback is None:
+            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)
@@ -1367,6 +1386,14 @@ def main():
     global nftables
     nftables = Nftables(sofile = 'src/.libs/libnftables.so')
 
+    global traceback
+    traceback = None
+    if enable_json_schema:
+        try:
+            import traceback
+        except:
+            pass
+
     test_files = files_ok = run_total = 0
     tests = passed = warnings = errors = 0
     global log_file
-- 
2.21.0