Stop using six; fixes #504. Get tests running with newer ZODB that ha…

…s removed a bunch of tests apparently.

CHANGES.rst

@@ -9,7 +9,7 @@
   to support newer compilers like GCC 13.
 - Compile in C++ 11 mode instead of whatever the compiler default was
   (sometimes C++ 03), because the latter is deprecated by Boost.
-
+- Stop relying on an undeclared dependency on ``six``. See :issue:`504`.
 
 4.0.0 (2023-12-11)
 ==================

src/relstorage/adapters/locker.py

@@ -20,7 +20,6 @@
 
 import abc
 import sys
-import six
 
 
 from relstorage._compat import ABC
@@ -277,10 +276,7 @@ def reraise_commit_lock_error(self, cursor, lock_stmt, kind):
         val = kind(message)
         val.__relstorage_cause__ = v
         del v
-        six.reraise(
-            kind,
-            val,
-            sys.exc_info()[2])
+        raise val.with_traceback(sys.exc_info()[2])
 
     # MySQL allows aggregates in the top level to use FOR UPDATE,
     # but PostgreSQL does not, so we have to use the second form.

src/relstorage/tests/hptestbase.py

@@ -480,6 +480,9 @@ def __tid_clock_needs_care(self):
         return getattr(adapter, 'RS_TEST_TXN_PACK_NEEDS_SLEEP', False)
 
     def __maybe_ignore_monotonic(self, cls, method_name):
+        if not hasattr(super(), method_name):
+            raise unittest.SkipTest('Method ' + method_name + ' not available')
+
         if not self.__tid_clock_needs_care():
             return getattr(super(), method_name)()
 
@@ -523,6 +526,8 @@ def checkLoadBeforeOld(self):
                                       'checkLoadBeforeOld')
 
     def checkSimpleHistory(self):
+        if not hasattr(super(), 'checkSimpleHistory'):
+            raise unittest.SkipTest('No test checkSimpleHistory')
         if not self.__tid_clock_needs_care():
             return super().checkSimpleHistory() # pylint:disable=no-member
         # This assumes that the `time` value in the storage.history()
@@ -605,7 +610,10 @@ def _run_with_storage_packing_at_packtime(self,
                                               find_packtime):
         # Ignore the pack timestamp given. Execute `find_packtime(storage)`
         # instead and use that.
-        meth = getattr(super(), methname)
+        try:
+            meth = getattr(super(), methname)
+        except AttributeError:
+            raise unittest.SkipTest('No method ' + methname) from None
         if not self.__tid_clock_needs_care():
             return meth()
 

src/relstorage/tests/reltestbase.py

@@ -225,9 +225,12 @@ def __thread_safe_wrapper(self):
                 self._storage = orig_storage
 
     def __generic_wrapped_test(self, meth_name):
-        meth = getattr(
-            super(),
-            meth_name)
+        try:
+            meth = getattr(
+                super(),
+                meth_name)
+        except AttributeError:
+            self.skipTest('No method ' + meth_name)
         try:
             with self.__thread_safe_wrapper():
                 meth()
@@ -1119,11 +1122,11 @@ def checkBTreesLengthStress(self): # pylint:disable=too-complex
         from ZODB.ConflictResolution import logger as CRLogger
         from BTrees.Length import Length
         import BTrees
-        from six import reraise
 
         def log_err(*args, **kwargs): # pylint:disable=unused-argument
             import sys
-            reraise(*sys.exc_info())
+            _t, v, _tb = sys.exc_info()
+            raise v
 
         CRLogger.debug = log_err
         CRLogger.exception = log_err