Resolve a bug in TransactionHook.

This commit makes TransactionHook more robust so that it isn't as susceptible
to failure when exceptions occur in *other* PecanHooks within a request.

2 files changed, 46 insertions, 2 deletions

diff --git a/pecan/hooks.py b/pecan/hooks.py
index 97dc416..f7422b8 100644
--- a/pecan/hooks.py
+++ b/pecan/hooks.py
@@ -144,7 +144,8 @@ class TransactionHook(PecanHook):
             self.start_ro()
 
     def before(self, state):
-        if self.is_transactional(state) and not state.request.transactional:
+        if self.is_transactional(state) \
+                and not getattr(state.request, 'transactional', False):
             self.clear()
             state.request.transactional = True
             self.start()
@@ -170,7 +171,7 @@ class TransactionHook(PecanHook):
         state.request.error = True
 
     def after(self, state):
-        if state.request.transactional:
+        if getattr(state.request, 'transactional', False):
             action_name = None
             if state.request.error:
                 action_name = 'after_rollback'
diff --git a/pecan/tests/test_hooks.py b/pecan/tests/test_hooks.py
index 5ad4d46..8f6c55a 100644
--- a/pecan/tests/test_hooks.py
+++ b/pecan/tests/test_hooks.py
@@ -992,6 +992,49 @@ class TestTransactionHook(PecanTestCase):
         assert run_hook[2] == 'commit'
         assert run_hook[3] == 'clear'
 
+    def test_transaction_hook_with_broken_hook(self):
+        """
+        In a scenario where a preceding hook throws an exception,
+        ensure that TransactionHook still rolls back properly.
+        """
+        run_hook = []
+
+        class RootController(object):
+            @expose()
+            def index(self):
+                return 'Hello, World!'
+
+        def gen(event):
+            return lambda: run_hook.append(event)
+
+        class MyCustomException(Exception):
+            pass
+
+        class MyHook(PecanHook):
+
+            def on_route(self, state):
+                raise MyCustomException('BROKEN!')
+
+        app = TestApp(make_app(RootController(), hooks=[
+            MyHook(),
+            TransactionHook(
+                start=gen('start'),
+                start_ro=gen('start_ro'),
+                commit=gen('commit'),
+                rollback=gen('rollback'),
+                clear=gen('clear')
+            )
+        ]))
+
+        self.assertRaises(
+            MyCustomException,
+            app.get,
+            '/'
+        )
+
+        assert len(run_hook) == 1
+        assert run_hook[0] == 'clear'
+
 
 class TestRequestViewerHook(PecanTestCase):