mojo: Add a runloop utility in python

mojo/python/tests/runloop_unittest.py

+# Copyright 2014 The Chromium Authors. All rights reserved.
+# Use of this source code is governed by a BSD-style license that can be
+# found in the LICENSE file.
+
+import unittest
+
+# pylint: disable=F0401
+import mojo.embedder
+from mojo import system
+
+
+def _Increment(array):
+  def _Closure():
+    array.append(0)
+  return _Closure
+
+
+class RunLoopTest(unittest.TestCase):
+
+  def setUp(self):
+    mojo.embedder.Init()
+
+  def testRunLoop(self):
+    loop = system.RunLoop()
+    array = []
+    for _ in xrange(10):
+      loop.PostDelayedTask(_Increment(array))
+    loop.RunUntilIdle()
+    self.assertEquals(len(array), 10)
+
+  def testRunLoopWithException(self):
+    loop = system.RunLoop()
+    def Throw():
+      raise Exception("error")
+    array = []
+    loop.PostDelayedTask(Throw)
+    loop.PostDelayedTask(_Increment(array))
+    with self.assertRaisesRegexp(Exception, '^error$'):
+      loop.Run()
+    self.assertEquals(len(array), 0)
+    loop.RunUntilIdle()
+    self.assertEquals(len(array), 1)