id,summary,reporter,owner,description,type,status,priority,milestone,component,resolution,keywords,cc,branch,branch_author,launchpad_bug
4921,trial reports errors when it shouldn't,djfroofy,,"I noticed some odd behaviors with trial where test reports result in errors even though the underlying errors are handled.  The behaviors I've noticed are as follows:

 1. If I log an error somewhere in code with log.err, then the test results in an error
 2. Errors inside a DeferredList result in a test error (even if the failure is handled)

Here is an example which demonstrates the above behaviors:

{{{
#!python
from twisted.internet import defer
from twisted.python import log
from twisted.trial.unittest import TestCase


class SomeComponent:
    fails = 0

    def on_failed(self, ignore):
        self.fails += 1

    def dowork1(self):
        ds = [ defer.succeed(1), defer.fail(ValueError('woops')) ]
        return defer.gatherResults(ds).addErrback(self.on_failed)

    def dowork2(self):
        return defer.fail(ValueError('woops')).addErrback(self.on_failed)

    def dowork3(self):
        return defer.fail(ValueError('woops')).addErrback(log.err).addErrback(self.on_failed)

class TheTestCase(TestCase):

    def test_failures1(self):
        component = SomeComponent()

        def check(result):
            self.assertEquals(component.fails, 1)
            print 'check succeeded'

        return component.dowork1().addCallback(check)

    def test_failures2(self):
        component = SomeComponent()

        def check(result):
            self.assertEquals(component.fails, 1)
            print 'check succeeded'

        return component.dowork2().addCallback(check)
    
    def test_failures3(self):
        component = SomeComponent()

        def check(result):
            self.assertEquals(component.fails, 0)
            print 'check succeeded'

        return component.dowork3().addCallback(check)
}}}

Output of test run on my machine:

{{{
test_wth
  TheTestCase
    test_failures1 ... check succeeded
                                                 [ERROR]
    test_failures2 ... check succeeded
                                                    [OK]
    test_failures3 ... check succeeded
                                                 [ERROR]

===============================================================================
[ERROR]: test_wth.TheTestCase.test_failures1

Traceback (most recent call last):
Failure: exceptions.ValueError: woops
===============================================================================
[ERROR]: test_wth.TheTestCase.test_failures3

Traceback (most recent call last):
Failure: exceptions.ValueError: woops
-------------------------------------------------------------------------------
Ran 3 tests in 0.005s

FAILED (errors=2, successes=1)
}}}
",defect,closed,normal,,trial,invalid,,jml,,,