docs(tests): tighten the foundation and corekit test prose from the post-sweep merges (#719)

tests/corekit/test_fields_collections.py

@@ -302,9 +302,9 @@ def subclasses(cls: 'Any') -> 'Any':
         fell_back = []  # type: list[str]
         total = 0
         for cls in set(subclasses(Schema)):
-            # Only this package's own declarations: a test that builds a schema
-            # of its own leaves it among the subclasses for as long as the
-            # import lives, and that is no longer one import per test (#1065).
+            # Only this package's own declarations: a schema a test builds for
+            # itself stays among the subclasses for as long as the import lives,
+            # and the whole class shares one import (#1065).
             if cls.__module__.split('.')[0] != 'pcapkit':
                 continue
             for name, field in getattr(cls, '__fields__', {}).items():

tests/corekit/test_fields_field.py

@@ -236,11 +236,10 @@ def setUp(self) -> None:
         self.FieldValueError = FieldValueError
         self.ceiling = field_module._MAX_ZERO_PAD_LENGTH
 
-        # The ledger is cumulative per context, so whatever ran earlier in this
-        # process -- a sibling class, another module -- has already earned
-        # allowance against it. Start every test from the unset default, as a
-        # freshly imported module would, rather than relying on a re-import per
-        # test to do it (GitHub issue #1065).
+        # The ledger is cumulative per context, and this class's tests share one
+        # import of the module, so an earlier test has already earned allowance
+        # against it. Start every test from the unset default, as a freshly
+        # imported module would (GitHub issue #1065).
         token = field_module._zero_pad_ledger.set(None)
         self.addCleanup(field_module._zero_pad_ledger.reset, token)
 

tests/foundation/registry/test_foundation.py

@@ -179,8 +179,8 @@ def test_registration_accepts_pcapkit_own_builtin_classes(self) -> None:
         # path instead of the public wrappers. The subject classes and the read-back
         # are unchanged.
         #
-        # NOTE: imported inside the test because ``setUp`` swaps in a fresh ``pcapkit`` in
-        # ``sys.modules``, which is why every sibling test imports locally too.
+        # NOTE: imported inside the test because ``setUp`` puts the class's own ``pcapkit``
+        # import in ``sys.modules``, which is why every sibling test imports locally too.
         # ``Extractor`` is needed by name here so the registries can be read back.
         from pcapkit.foundation.engines.pcap import PCAP as PCAP_Engine
         from pcapkit.foundation.extraction import Extractor

tests/foundation/test_extraction.py

@@ -89,11 +89,10 @@ def setUp(self) -> None:
 
         # Several tests here register into the four registries for real --
         # overwriting ``json``, ``dpkt``, ``ipv4`` and ``tcp`` with stand-ins,
-        # or adding ``unit-*`` names -- so each table is put back in place
-        # afterwards. A fresh import per test used to do that implicitly; without
-        # it, a later extraction ran the stand-in engine and hung, and
-        # :mod:`tests.interface.test_core` found engines it has no constant for
-        # (GitHub issue #1065).
+        # or adding ``unit-*`` names -- and the class shares one import, so each
+        # table is put back afterwards. Without that, a later extraction ran the
+        # stand-in engine and hung, and :mod:`tests.interface.test_core` found
+        # engines it has no constant for (GitHub issue #1065).
         for table in (Extractor.__output__, Extractor.__engine__,
                       Extractor.__reassembly__, Extractor.__traceflow__):
             self.addCleanup(lambda table=table, saved=dict(table): (table.clear(), table.update(saved)))