fix(protocols): export the L2TP data model from pcapkit.protocols.data.link (#1797)

pcapkit/protocols/data/__init__.py

@@ -61,6 +61,9 @@
     # Ethernet Protocol
     'Ethernet',
 
+    # Layer Two Tunnelling Protocol
+    'L2TP', 'L2TP_Flags',
+
     # BSD Loopback Encapsulation
     'Loopback',
 

pcapkit/protocols/data/link/__init__.py

@@ -9,6 +9,10 @@
 # Ethernet Protocol
 from pcapkit.protocols.data.link.ethernet import Ethernet
 
+# Layer Two Tunnelling Protocol
+from pcapkit.protocols.data.link.l2tp import L2TP
+from pcapkit.protocols.data.link.l2tp import Flags as L2TP_Flags
+
 # BSD Loopback Encapsulation
 from pcapkit.protocols.data.link.loopback import Loopback
 
@@ -23,6 +27,9 @@
     # Ethernet Protocol
     'Ethernet',
 
+    # Layer Two Tunnelling Protocol
+    'L2TP', 'L2TP_Flags',
+
     # BSD Loopback Encapsulation
     'Loopback',
 

pcapkit/protocols/data/link/l2tp.py

@@ -12,7 +12,7 @@
 
     from pcapkit.const.l2tp.type import Type
 
-__all__ = ['L2TP']
+__all__ = ['L2TP', 'Flags']
 
 
 @info_final

tests/protocols/link/test_l2tp_data_export_1797_unit.py

@@ -0,0 +1,64 @@
+# -*- coding: utf-8 -*-
+"""The L2TP data model is exported with its link-layer siblings (#1797).
+
+:mod:`pcapkit.protocols.data.link` re-exported the data models of ARP, Ethernet,
+Loopback and VLAN but not :mod:`pcapkit.protocols.data.link.l2tp`, although
+:mod:`pcapkit.protocols.schema.link` exports the schema of the same name. The
+omission was not a decision: the data model arrived in ``cdb5fef3f`` without
+touching the package, and no commit has ever named ``L2TP`` in it.
+
+:mod:`tests.project.test_public_api` could not see the gap. Its converse
+assertion reads the attributes a package *holds*, and a name the package never
+imported is not one of them -- so these cases check the package against the
+``__all__`` of each of its children instead.
+
+Nothing here reads a capture, so this belongs to the unit tier.
+
+"""
+from __future__ import annotations
+
+import importlib
+import pkgutil
+import unittest
+
+
+class L2TPDataExportTests(unittest.TestCase):
+    def test_link_package_reexports_every_child_export(self) -> None:
+        # Identity rather than name: siblings re-export nested models under a
+        # protocol prefix (``ARP_Address``, ``VLAN_TCI``), so the child's name
+        # need not be the package's.
+        package = importlib.import_module('pcapkit.protocols.data.link')
+        exported = {id(getattr(package, name)) for name in package.__all__}
+
+        children = [info.name for info in pkgutil.iter_modules(package.__path__, package.__name__ + '.')]
+        self.assertIn('pcapkit.protocols.data.link.l2tp', children)
+
+        missing = {}  # type: dict[str, list[str]]
+        for child_name in children:
+            child = importlib.import_module(child_name)
+            unexported = [name for name in getattr(child, '__all__', ())
+                          if id(getattr(child, name)) not in exported]
+            if unexported:
+                missing[child_name] = unexported
+
+        self.assertEqual(missing, {},
+                         'pcapkit.protocols.data.link does not re-export these names '
+                         'its submodules list in __all__')
+
+    def test_star_imports_bind_the_l2tp_models(self) -> None:
+        # ``Flags`` takes the ``<protocol>_<name>`` alias its siblings use
+        # (``IPv4_Flags``, ``TCP_Flags``) once it leaves its own module.
+        from pcapkit.protocols.data.link import l2tp
+
+        for module, flags in (('pcapkit.protocols.data.link.l2tp', 'Flags'),
+                              ('pcapkit.protocols.data.link', 'L2TP_Flags'),
+                              ('pcapkit.protocols.data', 'L2TP_Flags')):
+            namespace = {}  # type: dict[str, object]
+            exec(f'from {module} import *', namespace)  # pylint: disable=exec-used
+            with self.subTest(module=module):
+                self.assertIs(namespace.get('L2TP'), l2tp.L2TP)
+                self.assertIs(namespace.get(flags), l2tp.Flags)
+
+
+if __name__ == '__main__':
+    unittest.main()