[pitivi] undo: Ignore empty transactions when committing

[Alexandru Băluț <alexbalut src gnome org>]

commit 0de65fd03f2cfc95e0e6a0688bca0410450020fb
Author: Alexandru Băluț <alexandru balut gmail com>
Date:   Tue May 17 07:23:50 2016 +0200

    undo: Ignore empty transactions when committing
    
    There are cases when no action is pushed in a transaction. We could make
    sure this does not happen but it's easier to ignore them.
    
    Differential Revision: https://phabricator.freedesktop.org/D995

 pitivi/undo/undo.py |    5 ++++-
 tests/test_undo.py  |   18 ++++++++++++------
 2 files changed, 16 insertions(+), 7 deletions(-)
---
diff --git a/pitivi/undo/undo.py b/pitivi/undo/undo.py
index 8436ce7..e60d987 100644
--- a/pitivi/undo/undo.py
+++ b/pitivi/undo/undo.py
@@ -202,10 +202,13 @@ class UndoableActionLog(GObject.Object, Loggable):
             self.debug("Ignore commit because running")
             return
 
-        self.debug("Committing")
+        self.debug("Committing %s", action_group_name)
         stack = self._get_last_stack(pop=True)
         if action_group_name != stack.action_group_name:
             raise UndoWrongStateError("Unexpected commit", action_group_name, stack, self.stacks)
+        if not stack.done_actions:
+            self.debug("Ignore empty stack %s", stack.action_group_name)
+            return
         if not self.stacks:
             self.undo_stacks.append(stack)
         else:
diff --git a/tests/test_undo.py b/tests/test_undo.py
index ecd7192..33ba6ee 100644
--- a/tests/test_undo.py
+++ b/tests/test_undo.py
@@ -147,9 +147,12 @@ class TestUndoableActionLog(TestCase):
         self.assertTrue(self.log.is_in_transaction())
 
         self.assertEqual(self.log.undo_stacks, [])
+        self.log.push(mock.Mock())
         self.log.commit("meh")
-        self.assertEqual(len(self.signals), 2)
-        name, (stack,) = self.signals[1]
+        self.assertEqual(len(self.signals), 3)
+        name, (stack, action) = self.signals[1]
+        self.assertEqual(name, "push")
+        name, (stack,) = self.signals[2]
         self.assertEqual(name, "commit")
         self.assertFalse(self.log.is_in_transaction())
         self.assertEqual(len(self.log.undo_stacks), 1)
@@ -180,9 +183,12 @@ class TestUndoableActionLog(TestCase):
         self.assertTrue(self.log.is_in_transaction())
 
         self.assertEqual(self.log.undo_stacks, [])
+        self.log.push(mock.Mock())
         self.log.commit("nested")
-        self.assertEqual(len(self.signals), 3)
-        name, (stack,) = self.signals[2]
+        self.assertEqual(len(self.signals), 4)
+        name, (stack, action) = self.signals[2]
+        self.assertEqual(name, "push")
+        name, (stack,) = self.signals[3]
         self.assertEqual(name, "commit")
         self.assertTrue(self.log.is_in_transaction())
         self.assertEqual(len(self.log.undo_stacks), 0)
@@ -190,8 +196,8 @@ class TestUndoableActionLog(TestCase):
 
         self.assertEqual(self.log.undo_stacks, [])
         self.log.commit("meh")
-        self.assertEqual(len(self.signals), 4)
-        name, (stack,) = self.signals[3]
+        self.assertEqual(len(self.signals), 5)
+        name, (stack,) = self.signals[4]
         self.assertEqual(name, "commit")
         self.assertFalse(self.log.is_in_transaction())
         self.assertEqual(len(self.log.undo_stacks), 1)