[IMP] tests: partially backport classCleanups from CPython 3.8

This commit partially backports bpo-24412, which allows the definition of
class cleanups (addClassCleanup) and module cleanups (omitted),
similar to instance cleanups (addCleanup).

This is useful for tests that override unittest's setUpClass and
could crash during its execution: If this happens, it is possible that a
bunch of crap is left in the database or even worse, the cursor becomes
completely fucked; Thanks to the addClassCleanup, we can undo the damage
done by the setUpClass.

Another benefit is that it is called unconditionally after tearDownClass
is called, so it can also be called as a replacement and/or safer
tearDownClass.

3 files changed, 123 insertions, 3 deletions

diff --git a/odoo/modules/module.py b/odoo/modules/module.py
index 8d0dd5a7091..851395ba280 100644
--- a/odoo/modules/module.py
+++ b/odoo/modules/module.py
@@ -492,7 +492,8 @@ def run_unit_tests(module_name, position='at_install'):
     :rtype: bool
     """
     global current_test
-    from odoo.tests.common import TagsSelector # Avoid import loop
+    # avoid dependency hell
+    from odoo.tests.common import TagsSelector, OdooSuite
     current_test = module_name
     mods = get_test_modules(module_name)
     threading.currentThread().testing = True
@@ -501,7 +502,7 @@ def run_unit_tests(module_name, position='at_install'):
     r = True
     for m in mods:
         tests = unwrap_suite(unittest.TestLoader().loadTestsFromModule(m))
-        suite = unittest.TestSuite(t for t in tests if position_tag.check(t) and config_tags.check(t))
+        suite = OdooSuite(t for t in tests if position_tag.check(t) and config_tags.check(t))
 
         if suite.countTestCases():
             t0 = time.time()
diff --git a/odoo/service/server.py b/odoo/service/server.py
index aceedc42d60..9ca6212e0ce 100644
--- a/odoo/service/server.py
+++ b/odoo/service/server.py
@@ -20,6 +20,7 @@ import unittest
 import psutil
 import werkzeug.serving
 from werkzeug.debug import DebuggedApplication
+from odoo.tests.common import OdooSuite
 
 if os.name == 'posix':
     # Unix only for workers
@@ -1130,7 +1131,7 @@ def load_test_file_py(registry, test_file):
             for mod_mod in get_test_modules(mod):
                 mod_path, _ = os.path.splitext(getattr(mod_mod, '__file__', ''))
                 if test_path == mod_path:
-                    suite = unittest.TestSuite()
+                    suite = OdooSuite()
                     for t in unittest.TestLoader().loadTestsFromModule(mod_mod):
                         suite.addTest(t)
                     _logger.log(logging.INFO, 'running tests %s.', mod_mod.__name__)
diff --git a/odoo/tests/common.py b/odoo/tests/common.py
index 6035cf21d10..fcf02041518 100644
--- a/odoo/tests/common.py
+++ b/odoo/tests/common.py
@@ -19,6 +19,7 @@ import requests
 import shutil
 import signal
 import subprocess
+import sys
 import tempfile
 import threading
 import time
@@ -128,9 +129,126 @@ def new_test_user(env, login='', groups='base.group_user', context=None, **kwarg
 # ------------------------------------------------------------
 # Main classes
 # ------------------------------------------------------------
+class OdooSuite(unittest.suite.TestSuite):
+
+    if sys.version_info < (3, 8):
+        # Partial backport of bpo-24412, merged in CPython 3.8
+
+        def _handleClassSetup(self, test, result):
+            previousClass = getattr(result, '_previousTestClass', None)
+            currentClass = test.__class__
+            if currentClass == previousClass:
+                return
+            if result._moduleSetUpFailed:
+                return
+            if getattr(currentClass, "__unittest_skip__", False):
+                return
+
+            try:
+                currentClass._classSetupFailed = False
+            except TypeError:
+                # test may actually be a function
+                # so its class will be a builtin-type
+                pass
+
+            setUpClass = getattr(currentClass, 'setUpClass', None)
+            if setUpClass is not None:
+                unittest.suite._call_if_exists(result, '_setupStdout')
+                try:
+                    setUpClass()
+                except Exception as e:
+                    if isinstance(result, unittest.suite._DebugResult):
+                        raise
+                    currentClass._classSetupFailed = True
+                    className = unittest.util.strclass(currentClass)
+                    self._createClassOrModuleLevelException(result, e,
+                                                            'setUpClass',
+                                                            className)
+                finally:
+                    unittest.suite._call_if_exists(result, '_restoreStdout')
+                    if currentClass._classSetupFailed is True:
+                        currentClass.doClassCleanups()
+                        if len(currentClass.tearDown_exceptions) > 0:
+                            for exc in currentClass.tearDown_exceptions:
+                                self._createClassOrModuleLevelException(
+                                        result, exc[1], 'setUpClass', className,
+                                        info=exc)
+
+        def _createClassOrModuleLevelException(self, result, exc, method_name, parent, info=None):
+            errorName = f'{method_name} ({parent})'
+            self._addClassOrModuleLevelException(result, exc, errorName, info)
+
+        def _addClassOrModuleLevelException(self, result, exception, errorName, info=None):
+            error = unittest.suite._ErrorHolder(errorName)
+            addSkip = getattr(result, 'addSkip', None)
+            if addSkip is not None and isinstance(exception, unittest.case.SkipTest):
+                addSkip(error, str(exception))
+            else:
+                if not info:
+                    result.addError(error, sys.exc_info())
+                else:
+                    result.addError(error, info)
+
+        def _tearDownPreviousClass(self, test, result):
+            previousClass = getattr(result, '_previousTestClass', None)
+            currentClass = test.__class__
+            if currentClass == previousClass:
+                return
+            if getattr(previousClass, '_classSetupFailed', False):
+                return
+            if getattr(result, '_moduleSetUpFailed', False):
+                return
+            if getattr(previousClass, "__unittest_skip__", False):
+                return
+
+            tearDownClass = getattr(previousClass, 'tearDownClass', None)
+            if tearDownClass is not None:
+                unittest.suite._call_if_exists(result, '_setupStdout')
+                try:
+                    tearDownClass()
+                except Exception as e:
+                    if isinstance(result, unittest.suite._DebugResult):
+                        raise
+                    className = unittest.util.strclass(previousClass)
+                    self._createClassOrModuleLevelException(result, e,
+                                                            'tearDownClass',
+                                                            className)
+                finally:
+                    unittest.suite._call_if_exists(result, '_restoreStdout')
+                    previousClass.doClassCleanups()
+                    if len(previousClass.tearDown_exceptions) > 0:
+                        for exc in previousClass.tearDown_exceptions:
+                            className = unittest.util.strclass(previousClass)
+                            self._createClassOrModuleLevelException(result, exc[1],
+                                                                    'tearDownClass',
+                                                                    className,
+                                                                    info=exc)
 
 
 class TreeCase(unittest.TestCase):
+
+    if sys.version_info < (3, 8):
+        # Partial backport of bpo-24412, merged in CPython 3.8
+        _class_cleanups = []
+
+        @classmethod
+        def addClassCleanup(cls, function, *args, **kwargs):
+            """Same as addCleanup, except the cleanup items are called even if
+            setUpClass fails (unlike tearDownClass). Backport of bpo-24412."""
+            cls._class_cleanups.append((function, args, kwargs))
+
+        @classmethod
+        def doClassCleanups(cls):
+            """Execute all class cleanup functions. Normally called for you after tearDownClass.
+            Backport of bpo-24412."""
+            cls.tearDown_exceptions = []
+            while cls._class_cleanups:
+                function, args, kwargs = cls._class_cleanups.pop()
+                try:
+                    function(*args, **kwargs)
+                except Exception as exc:
+                    cls.tearDown_exceptions.append(sys.exc_info())
+
     def __init__(self, methodName='runTest'):
         super(TreeCase, self).__init__(methodName)
         self.addTypeEqualityFunc(etree._Element, self.assertTreesEqual)