git: Add test cases

Add git dissection test cases to existing testing suite for: finding git
packets, finding the Git Protocol version, finding the right amount of
Flush and Delimiter packets, not finding Malformed packets.

Part of #17093

epan/dissectors/packet-git.c

@@ -9,6 +9,9 @@
  * Copied from packet-pop.c
  *
  * SPDX-License-Identifier: GPL-2.0-or-later
+ *
+ * Current testing suite 'case_dissect_git' can be found at
+ * test/suite_dissection.py
  */
 
 #include "config.h"

test/suite_dissection.py

@@ -364,6 +364,31 @@ class case_dissect_tcp(subprocesstest.SubprocessTestCase):
             '-Ytls', '-Tfields', '-eframe.number', '-etls.record.length', '-2'))
         self.assertEqual(proc.stdout_str, '2\t16\n')
 
+@fixtures.mark_usefixtures('test_env')
+@fixtures.uses_fixtures
+class case_dissect_git(subprocesstest.SubprocessTestCase):
+    def test_git_prot(self, cmd_tshark, capture_file, features):
+        '''
+        Check for Git protocol version 2, flush and delimiter packets.
+        Ensure there are no malformed packets.
+        '''
+        proc = self.assertRun((cmd_tshark,
+                '-r', capture_file('gitOverTCP.pcap'),
+                '-Ygit', '-Tfields', '-egit.version', '-egit.packet_type',
+                '-zexpert', '-e_ws.expert',
+            ))
+        # `epan/dissectors/packet-git.c` parses the Git Protocol version
+        # from ASCII '1' or '2' to integers 49 or 50 in grep output.
+        # 0x0000 are flush packets.
+        # 0x0001 are delimiter packets.
+        # Pre-existing git Malformed Packets in this pcap were addressed
+        # with the parsing of the delimiter packets. This test ensures
+        # pcap gitOverTCP's delim packets are parsed and that there are no
+        # malformed packets with "Expert Info/Errors" in the same pcap.
+        # Additional test cases for other scenarios, i.e actually malformed
+        # git packets, might be required.
+        self.assertEqual(proc.stdout_str, '50\t\t\n\t0\t\n\t\t\n\t1,0\t\n')
+
 @fixtures.mark_usefixtures('test_env')
 @fixtures.uses_fixtures
 class case_dissect_tls(subprocesstest.SubprocessTestCase):