Allow customization of which exceptions should pass through ConfigurationMachine.issue10

Fixes #10.

3 files changed, 40 insertions, 4 deletions

diff --git a/CHANGES.rst b/CHANGES.rst
index 99874f1..eb5e594 100644
--- a/CHANGES.rst
+++ b/CHANGES.rst
@@ -46,6 +46,13 @@ Changes
   ``fromUnicode``. See `issue 28
   <https://github.com/zopefoundation/zope.configuration/issues/28>`_.
 
+- Add ``ConfigurationMachine.pass_through_exceptions`` to allow
+  customizing the exceptions that
+  ``ConfigurationMachine.execute_actions`` wraps in a
+  ``ConfigurationExecutionError``. See `issue 10
+  <https://github.com/zopefoundation/zope.configuration/issues/10>`_.
+
+
 4.1.0 (2017-04-26)
 ------------------
 
diff --git a/src/zope/configuration/config.py b/src/zope/configuration/config.py
index 774b265..61c37a8 100644
--- a/src/zope/configuration/config.py
+++ b/src/zope/configuration/config.py
@@ -333,6 +333,14 @@ class ConfigurationMachine(ConfigurationAdapterRegistry, ConfigurationContext):
     includepath = ()
     info = ''
 
+    #: These exceptions are allowed to be raised from `execute_actions`
+    #: without being re-wrapped into a `ConfigurationExecutionError`.
+    #: Users of instances of this class may modify this before calling `execute_actions`
+    #: if they need to propagate specific exceptions.
+    #:
+    #: .. versionadded:: 4.2.0
+    pass_through_exceptions = (KeyboardInterrupt, SystemExit)
+
     def __init__(self):
         super(ConfigurationMachine, self).__init__()
         self.actions = []
@@ -367,6 +375,9 @@ class ConfigurationMachine(ConfigurationAdapterRegistry, ConfigurationContext):
 
         This calls the action callables after resolving conflicts.
         """
+        pass_through_exceptions = self.pass_through_exceptions
+        if testing:
+            pass_through_exceptions = BaseException
         try:
             for action in resolveConflicts(self.actions):
                 callable = action['callable']
@@ -377,11 +388,9 @@ class ConfigurationMachine(ConfigurationAdapterRegistry, ConfigurationContext):
                 info = action['info']
                 try:
                     callable(*args, **kw)
-                except (KeyboardInterrupt, SystemExit): # pragma: no cover
+                except pass_through_exceptions:
                     raise
                 except:
-                    if testing:
-                        raise
                     t, v, tb = sys.exc_info()
                     try:
                         reraise(ConfigurationExecutionError(t, v, info),
diff --git a/src/zope/configuration/tests/test_config.py b/src/zope/configuration/tests/test_config.py
index 4835df9..42e7e2b 100644
--- a/src/zope/configuration/tests/test_config.py
+++ b/src/zope/configuration/tests/test_config.py
@@ -766,10 +766,30 @@ class ConfigurationMachineTests(_ConformsToIConfigurationContext,
         cm.action(None, _err)
         with self.assertRaises(ConfigurationExecutionError) as exc:
             cm.execute_actions()
-        self.assertTrue(exc.exception.etype is ValueError)
+        self.assertIs(exc.exception.etype, ValueError)
         self.assertEqual(str(exc.exception.evalue), "XXX")
         self.assertEqual(exc.exception.info, "INFO")
 
+    def _check_execute_actions_w_errors_wo_testing(self, ex_kind):
+        ex = ex_kind('XXX')
+        def _err(*args, **kw):
+            raise ex
+        cm = self._makeOne()
+        cm.info = 'INFO'
+        cm.action(None, _err)
+        with self.assertRaises(ex_kind) as exc:
+            cm.execute_actions()
+
+        self.assertIs(exc.exception, ex)
+
+    def test_execute_actions_w_errors_wo_testing_SystemExit(self):
+        # It gets passed through as-is
+        self._check_execute_actions_w_errors_wo_testing(SystemExit)
+
+    def test_execute_actions_w_errors_wo_testing_KeyboardInterrupt(self):
+        # It gets passed through as-is
+        self._check_execute_actions_w_errors_wo_testing(KeyboardInterrupt)
+
     def test_keyword_handling(self):
         # This is really an integraiton test.
         from zope.configuration.config import metans