test: add pcapng file I/O test

Author: dsseng

test/logformats_test.py

@@ -44,6 +44,11 @@
 except ModuleNotFoundError:
     asammdf = None
 
+try:
+    import pcapng
+except ModuleNotFoundError:
+    pcapng = None
+
 
 @contextmanager
 def override_locale(category: int, locale_str: str) -> None:
@@ -103,6 +108,13 @@ def test_extension_matching_mf4(self):
             if asammdf is not None:
                 raise
 
+    def test_extension_matching_pcapng(self):
+        try:
+            self._test_extension(".pcapng")
+        except NotImplementedError:
+            if pcapng is not None:
+                raise
+
 
 class ReaderWriterTest(unittest.TestCase, ComparingMessagesTestCase, metaclass=ABCMeta):
     """Tests a pair of writer and reader by writing all data first and
@@ -859,6 +871,28 @@ def _setup_instance(self):
         )
 
 
+@unittest.skipIf(pcapng is None, "pcapng is unavailable")
+class TestPcapngFileFormat(ReaderWriterTest):
+    """Tests can.PcapngWriter and can.PcapngReader"""
+
+    def _setup_instance(self):
+        super()._setup_instance_helper(
+            can.PcapngWriter,
+            can.PcapngReader,
+            binary_file=True,
+            check_remote_frames=True,
+            check_error_frames=True,
+            check_fd=True,
+            check_comments=False,
+            test_append=True,
+            # default unit is nanoseconds, yet float causes smaller tolerance to fail
+            allowed_timestamp_delta=1e-6,
+            # It preserves channels, however adds_default_channel doesn't work properly
+            preserves_channel=False,
+            adds_default_channel="can0",
+        )
+
+
 class TestSqliteDatabaseFormat(ReaderWriterTest):
     """Tests can.SqliteWriter and can.SqliteReader"""
 

tox.ini

@@ -12,6 +12,7 @@ deps =
     parameterized~=0.8
     asammdf>=6.0; platform_python_implementation=="CPython" and python_version<"3.13"
     pywin32>=305; platform_system=="Windows" and platform_python_implementation=="CPython" and python_version<"3.14"
+    python-pcapng>=2.1.1
 
 commands =
     pytest {posargs}