Fixes for ticket https://bugs.launchpad.net/bugs/266921

I have cleaned up all the tests in test_asyncfrontendbase.py so that
they adhere to good twisted testing protocols.

IPython/frontend/tests/test_asyncfrontendbase.py

@@ -1,6 +1,6 b''
 # encoding: utf-8
 
-"""This file contains unittests for the frontendbase module."""
+"""This file contains unittests for the asyncfrontendbase module."""
 
 __docformat__ = "restructuredtext en"
 
@@ -15,17 +15,17 b' __docformat__ = "restructuredtext en"'
 # Imports                                                                   
 #---------------------------------------------------------------------------
 
-import unittest
 
 try:
+    from twisted.trial import unittest
     from IPython.frontend.asyncfrontendbase import AsyncFrontEndBase
     from IPython.frontend import frontendbase 
     from IPython.kernel.engineservice import EngineService
+    from IPython.testing.parametric import Parametric, parametric
 except ImportError:
     import nose
     raise nose.SkipTest("This test requires zope.interface, Twisted and Foolscap")
 
-from IPython.testing.decorators import skip
 
 class FrontEndCallbackChecker(AsyncFrontEndBase):
     """FrontEndBase subclass for checking callbacks"""
@@ -44,14 +44,11 b' class FrontEndCallbackChecker(AsyncFrontEndBase):'
         self.renderResultCalled = True
         return result
     
-    
     def render_error(self, failure):
         self.renderErrorCalled = True
         return failure
-    
 
 
-    
 class TestAsyncFrontendBase(unittest.TestCase):
     def setUp(self):
         """Setup the EngineService and FrontEndBase"""
@@ -59,97 +56,56 b' class TestAsyncFrontendBase(unittest.TestCase):'
         self.fb = FrontEndCallbackChecker(engine=EngineService())
     
     def test_implements_IFrontEnd(self):
-        assert(frontendbase.IFrontEnd.implementedBy(
+        self.assert_(frontendbase.IFrontEnd.implementedBy(
                                     AsyncFrontEndBase))
     
     def test_is_complete_returns_False_for_incomplete_block(self):
-        """"""
-        
         block = """def test(a):"""
-        
-        assert(self.fb.is_complete(block) == False)
+        self.assert_(self.fb.is_complete(block) == False)
     
     def test_is_complete_returns_True_for_complete_block(self):
-        """"""
-        
         block = """def test(a): pass"""
-            
-        assert(self.fb.is_complete(block))
-        
+        self.assert_(self.fb.is_complete(block))
         block = """a=3"""
-        
-        assert(self.fb.is_complete(block))
+        self.assert_(self.fb.is_complete(block))
     
     def test_blockID_added_to_result(self):
         block = """3+3"""
-        
         d = self.fb.execute(block, blockID='TEST_ID')
-        
-        d.addCallback(self.checkBlockID, expected='TEST_ID')
+        d.addCallback(lambda r: self.assert_(r['blockID']=='TEST_ID'))
+        return d
     
     def test_blockID_added_to_failure(self):
         block = "raise Exception()"
-        
         d = self.fb.execute(block,blockID='TEST_ID')
-        d.addErrback(self.checkFailureID, expected='TEST_ID')
-    
-    def checkBlockID(self, result, expected=""):
-        assert(result['blockID'] == expected)
-    
-    
-    def checkFailureID(self, failure, expected=""):
-        assert(failure.blockID == expected)
-    
+        d.addErrback(lambda f: self.assert_(f.blockID=='TEST_ID'))
+        return d
     
     def test_callbacks_added_to_execute(self):
-        """test that
-        update_cell_prompt
-        render_result
-        
-        are added to execute request
-        """
-        
         d = self.fb.execute("10+10")
-        d.addCallback(self.checkCallbacks)
+        d.addCallback(lambda r: self.assert_(self.fb.updateCalled and self.fb.renderResultCalled))
+        return d
     
-    def checkCallbacks(self, result):
-        assert(self.fb.updateCalled)
-        assert(self.fb.renderResultCalled)
-    
-    @skip("This test fails and lead to an unhandled error in a Deferred.")
     def test_error_callback_added_to_execute(self):
-        """test that render_error called on execution error"""
+        """Test that render_error called on execution error."""
         
         d = self.fb.execute("raise Exception()")
-        d.addCallback(self.checkRenderError)
-    
-    def checkRenderError(self, result):
-        assert(self.fb.renderErrorCalled)
+        d.addErrback(lambda f: self.assert_(self.fb.renderErrorCalled))
+        return d
     
     def test_history_returns_expected_block(self):
-        """Make sure history browsing doesn't fail"""
+        """Make sure history browsing doesn't fail."""
         
         blocks = ["a=1","a=2","a=3"]
-        for b in blocks:
-            d = self.fb.execute(b)
-        
-        # d is now the deferred for the last executed block
-        d.addCallback(self.historyTests, blocks)
-        
-    
-    def historyTests(self, result, blocks):
-        """historyTests"""
-        
-        assert(len(blocks) >= 3)
-        assert(self.fb.get_history_previous("") == blocks[-2])
-        assert(self.fb.get_history_previous("") == blocks[-3])
-        assert(self.fb.get_history_next() == blocks[-2])
-    
-    
-    def test_history_returns_none_at_startup(self):
-        """test_history_returns_none_at_startup"""
-        
-        assert(self.fb.get_history_previous("")==None)
-        assert(self.fb.get_history_next()==None)
-    
-    
+        d = self.fb.execute(blocks[0])
+        d.addCallback(lambda _: self.fb.execute(blocks[1]))
+        d.addCallback(lambda _: self.fb.execute(blocks[2]))
+        d.addCallback(lambda _: self.assert_(self.fb.get_history_previous("")==blocks[-2]))
+        d.addCallback(lambda _: self.assert_(self.fb.get_history_previous("")==blocks[-3]))
+        d.addCallback(lambda _: self.assert_(self.fb.get_history_next()==blocks[-2]))
+        return d
+    
+    def test_history_returns_none_at_startup(self):        
+        self.assert_(self.fb.get_history_previous("")==None)
+        self.assert_(self.fb.get_history_next()==None)
+