integration test for trac #2951

add a test for the case which the db is too slow to complete the newLog before end of the step

if I revert previous commit, I get the error reported by benallard

===============================================================================
[ERROR]
Traceback (most recent call last):
  File "/Users/ptardy/dev/bb/buildbot-heroku/buildbot/master/buildbot/process/buildstep.py", line 157, in next
    self._catchup()
  File "/Users/ptardy/dev/bb/buildbot-heroku/buildbot/master/buildbot/process/buildstep.py", line 159, in _catchup
    self.step._start_unhandled_deferreds.append(d)
exceptions.AttributeError: 'NoneType' object has no attribute 'append'

buildbot.test.integration.test_custom_buildstep.RunSteps.test_OldStyleCustomBuildStepSlowDB
buildbot.test.integration.test_custom_buildstep.RunSteps.test_OldStyleCustomBuildStepSlowDB
===============================================================================
[ERROR]
Traceback (most recent call last):
  File "/Users/ptardy/dev/bb/buildbot-heroku/buildbot/master/buildbot/process/buildstep.py", line 135, in gotAsync
    self._catchup()
  File "/Users/ptardy/dev/bb/buildbot-heroku/buildbot/master/buildbot/process/buildstep.py", line 159, in _catchup
    self.step._start_unhandled_deferreds.append(d)
exceptions.AttributeError: 'NoneType' object has no attribute 'append'

buildbot.test.integration.test_custom_buildstep.RunSteps.test_OldStyleCustomBuildStepSlowDB

Signed-off-by: Pierre Tardy <pierre.tardy@intel.com>

master/buildbot/test/integration/test_custom_buildstep.py

@@ -227,7 +227,21 @@ def assertLogs(self, exp_logs):
         self.assertEqual(got_logs, exp_logs)
 
     @defer.inlineCallbacks
-    def test_OldStyleCustomBuildStep(self):
+    def doOldStyleCustomBuildStep(self, slowDB=False):
+        if slowDB:
+            oldNewLog = self.master.data.updates.newLog
+
+            def newLog(*args, **kw):
+                d = defer.Deferred()
+
+                def delayed():
+                    r = oldNewLog(*args, **kw)
+                    r.addCallback(d.callback)
+
+                reactor.callLater(.1, delayed)
+                return d
+            self.patch(self.master.data.updates, "newLog", newLog)
+
         self.factory.addStep(OldStyleCustomBuildStep(arg1=1, arg2=2))
         yield self.do_test_step()
 
@@ -239,10 +253,18 @@ def test_OldStyleCustomBuildStep(self):
             # 'stdout\n\xe2\x98\x83\nstderr\n',
             u'ostdout\no\N{SNOWMAN}\nestderr\n',
             u'obs':
+            # if slowDB, the observer wont see anything before the end of this instant step
+            u'Observer saw []\n' if slowDB else
             # 'Observer saw [\'stdout\\n\', \'\\xe2\\x98\\x83\\n\']',
             u'Observer saw [u\'stdout\\n\', u\'\\u2603\\n\']\n',
         })
 
+    def test_OldStyleCustomBuildStep(self):
+        return self.doOldStyleCustomBuildStep(False)
+
+    def test_OldStyleCustomBuildStepSlowDB(self):
+        return self.doOldStyleCustomBuildStep(True)
+
     @defer.inlineCallbacks
     def test_OldStyleCustomBuildStep_failure(self):
         self.factory.addStep(OldStyleCustomBuildStep(arg1=1, arg2=2, doFail=1))