aboutsummaryrefslogtreecommitdiffstats
path: root/lib/python2.7/site-packages/Twisted-12.2.0-py2.7-linux-x86_64.egg/twisted/test/test_log.py
blob: 8c9a44a3841a3a8d39f65a630ddd685478cef8c5 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
# Copyright (c) Twisted Matrix Laboratories.
# See LICENSE for details.

"""
Tests for L{twisted.python.log}.
"""

import os, sys, time, logging, warnings, calendar
from cStringIO import StringIO

from twisted.trial import unittest

from twisted.python import log, failure


class FakeWarning(Warning):
    """
    A unique L{Warning} subclass used by tests for interactions of
    L{twisted.python.log} with the L{warnings} module.
    """



class LogTest(unittest.TestCase):

    def setUp(self):
        self.catcher = []
        self.observer = self.catcher.append
        log.addObserver(self.observer)
        self.addCleanup(log.removeObserver, self.observer)


    def testObservation(self):
        catcher = self.catcher
        log.msg("test", testShouldCatch=True)
        i = catcher.pop()
        self.assertEqual(i["message"][0], "test")
        self.assertEqual(i["testShouldCatch"], True)
        self.assertIn("time", i)
        self.assertEqual(len(catcher), 0)


    def testContext(self):
        catcher = self.catcher
        log.callWithContext({"subsystem": "not the default",
                             "subsubsystem": "a",
                             "other": "c"},
                            log.callWithContext,
                            {"subsubsystem": "b"}, log.msg, "foo", other="d")
        i = catcher.pop()
        self.assertEqual(i['subsubsystem'], 'b')
        self.assertEqual(i['subsystem'], 'not the default')
        self.assertEqual(i['other'], 'd')
        self.assertEqual(i['message'][0], 'foo')

    def testErrors(self):
        for e, ig in [("hello world","hello world"),
                      (KeyError(), KeyError),
                      (failure.Failure(RuntimeError()), RuntimeError)]:
            log.err(e)
            i = self.catcher.pop()
            self.assertEqual(i['isError'], 1)
            self.flushLoggedErrors(ig)

    def testErrorsWithWhy(self):
        for e, ig in [("hello world","hello world"),
                      (KeyError(), KeyError),
                      (failure.Failure(RuntimeError()), RuntimeError)]:
            log.err(e, 'foobar')
            i = self.catcher.pop()
            self.assertEqual(i['isError'], 1)
            self.assertEqual(i['why'], 'foobar')
            self.flushLoggedErrors(ig)


    def test_erroneousErrors(self):
        """
        Exceptions raised by log observers are logged but the observer which
        raised the exception remains registered with the publisher.  These
        exceptions do not prevent the event from being sent to other observers
        registered with the publisher.
        """
        L1 = []
        L2 = []
        def broken(events):
            1 // 0

        for observer in [L1.append, broken, L2.append]:
            log.addObserver(observer)
            self.addCleanup(log.removeObserver, observer)

        for i in xrange(3):
            # Reset the lists for simpler comparison.
            L1[:] = []
            L2[:] = []

            # Send out the event which will break one of the observers.
            log.msg("Howdy, y'all.")

            # The broken observer should have caused this to be logged.
            excs = self.flushLoggedErrors(ZeroDivisionError)
            self.assertEqual(len(excs), 1)

            # Both other observers should have seen the message.
            self.assertEqual(len(L1), 2)
            self.assertEqual(len(L2), 2)

            # The order is slightly wrong here.  The first event should be
            # delivered to all observers; then, errors should be delivered.
            self.assertEqual(L1[1]['message'], ("Howdy, y'all.",))
            self.assertEqual(L2[0]['message'], ("Howdy, y'all.",))


    def test_doubleErrorDoesNotRemoveObserver(self):
        """
        If logging causes an error, make sure that if logging the fact that
        logging failed also causes an error, the log observer is not removed.
        """
        events = []
        errors = []
        publisher = log.LogPublisher()

        class FailingObserver(object):
            calls = 0
            def log(self, msg, **kwargs):
                # First call raises RuntimeError:
                self.calls += 1
                if self.calls < 2:
                    raise RuntimeError("Failure #%s" % (self.calls,))
                else:
                    events.append(msg)

        observer = FailingObserver()
        publisher.addObserver(observer.log)
        self.assertEqual(publisher.observers, [observer.log])

        try:
            # When observer throws, the publisher attempts to log the fact by
            # calling self._err()... which also fails with recursion error:
            oldError = publisher._err

            def failingErr(failure, why, **kwargs):
                errors.append(failure.value)
                raise RuntimeError("Fake recursion error")

            publisher._err = failingErr
            publisher.msg("error in first observer")
        finally:
            publisher._err = oldError
            # Observer should still exist; we do this in finally since before
            # bug was fixed the test would fail due to uncaught exception, so
            # we want failing assert too in that case:
            self.assertEqual(publisher.observers, [observer.log])

        # The next message should succeed:
        publisher.msg("but this should succeed")

        self.assertEqual(observer.calls, 2)
        self.assertEqual(len(events), 1)
        self.assertEqual(events[0]['message'], ("but this should succeed",))
        self.assertEqual(len(errors), 1)
        self.assertIsInstance(errors[0], RuntimeError)


    def test_showwarning(self):
        """
        L{twisted.python.log.showwarning} emits the warning as a message
        to the Twisted logging system.
        """
        publisher = log.LogPublisher()
        publisher.addObserver(self.observer)

        publisher.showwarning(
            FakeWarning("unique warning message"), FakeWarning,
            "warning-filename.py", 27)
        event = self.catcher.pop()
        self.assertEqual(
            event['format'] % event,
            'warning-filename.py:27: twisted.test.test_log.FakeWarning: '
            'unique warning message')
        self.assertEqual(self.catcher, [])

        # Python 2.6 requires that any function used to override the
        # warnings.showwarning API accept a "line" parameter or a
        # deprecation warning is emitted.
        publisher.showwarning(
            FakeWarning("unique warning message"), FakeWarning,
            "warning-filename.py", 27, line=object())
        event = self.catcher.pop()
        self.assertEqual(
            event['format'] % event,
            'warning-filename.py:27: twisted.test.test_log.FakeWarning: '
            'unique warning message')
        self.assertEqual(self.catcher, [])


    def test_warningToFile(self):
        """
        L{twisted.python.log.showwarning} passes warnings with an explicit file
        target on to the underlying Python warning system.
        """
        message = "another unique message"
        category = FakeWarning
        filename = "warning-filename.py"
        lineno = 31

        output = StringIO()
        log.showwarning(message, category, filename, lineno, file=output)

        self.assertEqual(
            output.getvalue(),
            warnings.formatwarning(message, category, filename, lineno))

        # In Python 2.6, warnings.showwarning accepts a "line" argument which
        # gives the source line the warning message is to include.
        if sys.version_info >= (2, 6):
            line = "hello world"
            output = StringIO()
            log.showwarning(message, category, filename, lineno, file=output,
                            line=line)

            self.assertEqual(
                output.getvalue(),
                warnings.formatwarning(message, category, filename, lineno,
                                       line))


    def test_publisherReportsBrokenObserversPrivately(self):
        """
        Log publisher does not use the global L{log.err} when reporting broken
        observers.
        """
        errors = []
        def logError(eventDict):
            if eventDict.get("isError"):
                errors.append(eventDict["failure"].value)

        def fail(eventDict):
            raise RuntimeError("test_publisherLocalyReportsBrokenObservers")

        publisher = log.LogPublisher()
        publisher.addObserver(logError)
        publisher.addObserver(fail)

        publisher.msg("Hello!")
        self.assertEqual(publisher.observers, [logError, fail])
        self.assertEqual(len(errors), 1)
        self.assertIsInstance(errors[0], RuntimeError)



class FakeFile(list):
    def write(self, bytes):
        self.append(bytes)

    def flush(self):
        pass

class EvilStr:
    def __str__(self):
        1//0

class EvilRepr:
    def __str__(self):
        return "Happy Evil Repr"
    def __repr__(self):
        1//0

class EvilReprStr(EvilStr, EvilRepr):
    pass

class LogPublisherTestCaseMixin:
    def setUp(self):
        """
        Add a log observer which records log events in C{self.out}.  Also,
        make sure the default string encoding is ASCII so that
        L{testSingleUnicode} can test the behavior of logging unencodable
        unicode messages.
        """
        self.out = FakeFile()
        self.lp = log.LogPublisher()
        self.flo = log.FileLogObserver(self.out)
        self.lp.addObserver(self.flo.emit)

        try:
            str(u'\N{VULGAR FRACTION ONE HALF}')
        except UnicodeEncodeError:
            # This is the behavior we want - don't change anything.
            self._origEncoding = None
        else:
            reload(sys)
            self._origEncoding = sys.getdefaultencoding()
            sys.setdefaultencoding('ascii')


    def tearDown(self):
        """
        Verify that everything written to the fake file C{self.out} was a
        C{str}.  Also, restore the default string encoding to its previous
        setting, if it was modified by L{setUp}.
        """
        for chunk in self.out:
            self.failUnless(isinstance(chunk, str), "%r was not a string" % (chunk,))

        if self._origEncoding is not None:
            sys.setdefaultencoding(self._origEncoding)
            del sys.setdefaultencoding



class LogPublisherTestCase(LogPublisherTestCaseMixin, unittest.TestCase):
    def testSingleString(self):
        self.lp.msg("Hello, world.")
        self.assertEqual(len(self.out), 1)


    def testMultipleString(self):
        # Test some stupid behavior that will be deprecated real soon.
        # If you are reading this and trying to learn how the logging
        # system works, *do not use this feature*.
        self.lp.msg("Hello, ", "world.")
        self.assertEqual(len(self.out), 1)


    def testSingleUnicode(self):
        self.lp.msg(u"Hello, \N{VULGAR FRACTION ONE HALF} world.")
        self.assertEqual(len(self.out), 1)
        self.assertIn('with str error', self.out[0])
        self.assertIn('UnicodeEncodeError', self.out[0])



class FileObserverTestCase(LogPublisherTestCaseMixin, unittest.TestCase):
    def test_getTimezoneOffset(self):
        """
        Attempt to verify that L{FileLogObserver.getTimezoneOffset} returns
        correct values for the current C{TZ} environment setting.  Do this
        by setting C{TZ} to various well-known values and asserting that the
        reported offset is correct.
        """
        localDaylightTuple = (2006, 6, 30, 0, 0, 0, 4, 181, 1)
        utcDaylightTimestamp = time.mktime(localDaylightTuple)
        localStandardTuple = (2007, 1, 31, 0, 0, 0, 2, 31, 0)
        utcStandardTimestamp = time.mktime(localStandardTuple)

        originalTimezone = os.environ.get('TZ', None)
        try:
            # Test something west of UTC
            os.environ['TZ'] = 'America/New_York'
            time.tzset()
            self.assertEqual(
                self.flo.getTimezoneOffset(utcDaylightTimestamp),
                14400)
            self.assertEqual(
                self.flo.getTimezoneOffset(utcStandardTimestamp),
                18000)

            # Test something east of UTC
            os.environ['TZ'] = 'Europe/Berlin'
            time.tzset()
            self.assertEqual(
                self.flo.getTimezoneOffset(utcDaylightTimestamp),
                -7200)
            self.assertEqual(
                self.flo.getTimezoneOffset(utcStandardTimestamp),
                -3600)

            # Test a timezone that doesn't have DST
            os.environ['TZ'] = 'Africa/Johannesburg'
            time.tzset()
            self.assertEqual(
                self.flo.getTimezoneOffset(utcDaylightTimestamp),
                -7200)
            self.assertEqual(
                self.flo.getTimezoneOffset(utcStandardTimestamp),
                -7200)
        finally:
            if originalTimezone is None:
                del os.environ['TZ']
            else:
                os.environ['TZ'] = originalTimezone
            time.tzset()
    if getattr(time, 'tzset', None) is None:
        test_getTimezoneOffset.skip = (
            "Platform cannot change timezone, cannot verify correct offsets "
            "in well-known timezones.")


    def test_timeFormatting(self):
        """
        Test the method of L{FileLogObserver} which turns a timestamp into a
        human-readable string.
        """
        when = calendar.timegm((2001, 2, 3, 4, 5, 6, 7, 8, 0))

        # Pretend to be in US/Eastern for a moment
        self.flo.getTimezoneOffset = lambda when: 18000
        self.assertEqual(self.flo.formatTime(when), '2001-02-02 23:05:06-0500')

        # Okay now we're in Eastern Europe somewhere
        self.flo.getTimezoneOffset = lambda when: -3600
        self.assertEqual(self.flo.formatTime(when), '2001-02-03 05:05:06+0100')

        # And off in the Pacific or someplace like that
        self.flo.getTimezoneOffset = lambda when: -39600
        self.assertEqual(self.flo.formatTime(when), '2001-02-03 15:05:06+1100')

        # One of those weird places with a half-hour offset timezone
        self.flo.getTimezoneOffset = lambda when: 5400
        self.assertEqual(self.flo.formatTime(when), '2001-02-03 02:35:06-0130')

        # Half-hour offset in the other direction
        self.flo.getTimezoneOffset = lambda when: -5400
        self.assertEqual(self.flo.formatTime(when), '2001-02-03 05:35:06+0130')

        # Test an offset which is between 0 and 60 minutes to make sure the
        # sign comes out properly in that case.
        self.flo.getTimezoneOffset = lambda when: 1800
        self.assertEqual(self.flo.formatTime(when), '2001-02-03 03:35:06-0030')

        # Test an offset between 0 and 60 minutes in the other direction.
        self.flo.getTimezoneOffset = lambda when: -1800
        self.assertEqual(self.flo.formatTime(when), '2001-02-03 04:35:06+0030')

        # If a strftime-format string is present on the logger, it should
        # use that instead.  Note we don't assert anything about day, hour
        # or minute because we cannot easily control what time.strftime()
        # thinks the local timezone is.
        self.flo.timeFormat = '%Y %m'
        self.assertEqual(self.flo.formatTime(when), '2001 02')


    def test_loggingAnObjectWithBroken__str__(self):
        #HELLO, MCFLY
        self.lp.msg(EvilStr())
        self.assertEqual(len(self.out), 1)
        # Logging system shouldn't need to crap itself for this trivial case
        self.assertNotIn('UNFORMATTABLE', self.out[0])


    def test_formattingAnObjectWithBroken__str__(self):
        self.lp.msg(format='%(blat)s', blat=EvilStr())
        self.assertEqual(len(self.out), 1)
        self.assertIn('Invalid format string or unformattable object', self.out[0])


    def test_brokenSystem__str__(self):
        self.lp.msg('huh', system=EvilStr())
        self.assertEqual(len(self.out), 1)
        self.assertIn('Invalid format string or unformattable object', self.out[0])


    def test_formattingAnObjectWithBroken__repr__Indirect(self):
        self.lp.msg(format='%(blat)s', blat=[EvilRepr()])
        self.assertEqual(len(self.out), 1)
        self.assertIn('UNFORMATTABLE OBJECT', self.out[0])


    def test_systemWithBroker__repr__Indirect(self):
        self.lp.msg('huh', system=[EvilRepr()])
        self.assertEqual(len(self.out), 1)
        self.assertIn('UNFORMATTABLE OBJECT', self.out[0])


    def test_simpleBrokenFormat(self):
        self.lp.msg(format='hooj %s %s', blat=1)
        self.assertEqual(len(self.out), 1)
        self.assertIn('Invalid format string or unformattable object', self.out[0])


    def test_ridiculousFormat(self):
        self.lp.msg(format=42, blat=1)
        self.assertEqual(len(self.out), 1)
        self.assertIn('Invalid format string or unformattable object', self.out[0])


    def test_evilFormat__repr__And__str__(self):
        self.lp.msg(format=EvilReprStr(), blat=1)
        self.assertEqual(len(self.out), 1)
        self.assertIn('PATHOLOGICAL', self.out[0])


    def test_strangeEventDict(self):
        """
        This kind of eventDict used to fail silently, so test it does.
        """
        self.lp.msg(message='', isError=False)
        self.assertEqual(len(self.out), 0)


    def test_startLogging(self):
        """
        startLogging() installs FileLogObserver and overrides sys.stdout and
        sys.stderr.
        """
        # When done with test, reset stdout and stderr to current values:
        origStdout, origStderr = sys.stdout, sys.stderr
        self.addCleanup(setattr, sys, 'stdout', sys.stdout)
        self.addCleanup(setattr, sys, 'stderr', sys.stderr)
        fakeFile = StringIO()
        observer = log.startLogging(fakeFile)
        self.addCleanup(observer.stop)
        log.msg("Hello!")
        self.assertIn("Hello!", fakeFile.getvalue())
        self.assertIsInstance(sys.stdout, log.StdioOnnaStick)
        self.assertEqual(sys.stdout.isError, False)
        self.assertEqual(sys.stdout.encoding, 
                         origStdout.encoding or sys.getdefaultencoding())
        self.assertIsInstance(sys.stderr, log.StdioOnnaStick)
        self.assertEqual(sys.stderr.isError, True)
        self.assertEqual(sys.stderr.encoding,
                         origStderr.encoding or sys.getdefaultencoding())


    def test_startLoggingTwice(self):
        """
        There are some obscure error conditions that can occur when logging is
        started twice. See http://twistedmatrix.com/trac/ticket/3289 for more
        information.
        """
        # The bug is particular to the way that the t.p.log 'global' function
        # handle stdout. If we use our own stream, the error doesn't occur. If
        # we use our own LogPublisher, the error doesn't occur.
        sys.stdout = StringIO()
        self.addCleanup(setattr, sys, 'stdout', sys.stdout)
        self.addCleanup(setattr, sys, 'stderr', sys.stderr)

        def showError(eventDict):
            if eventDict['isError']:
                sys.__stdout__.write(eventDict['failure'].getTraceback())

        log.addObserver(showError)
        self.addCleanup(log.removeObserver, showError)
        observer = log.startLogging(sys.stdout)
        self.addCleanup(observer.stop)
        # At this point, we expect that sys.stdout is a StdioOnnaStick object.
        self.assertIsInstance(sys.stdout, log.StdioOnnaStick)
        fakeStdout = sys.stdout
        observer = log.startLogging(sys.stdout)
        self.assertIdentical(sys.stdout, fakeStdout)


class PythonLoggingObserverTestCase(unittest.TestCase):
    """
    Test the bridge with python logging module.
    """
    def setUp(self):
        self.out = StringIO()

        rootLogger = logging.getLogger("")
        self.originalLevel = rootLogger.getEffectiveLevel()
        rootLogger.setLevel(logging.DEBUG)
        self.hdlr = logging.StreamHandler(self.out)
        fmt = logging.Formatter(logging.BASIC_FORMAT)
        self.hdlr.setFormatter(fmt)
        rootLogger.addHandler(self.hdlr)

        self.lp = log.LogPublisher()
        self.obs = log.PythonLoggingObserver()
        self.lp.addObserver(self.obs.emit)

    def tearDown(self):
        rootLogger = logging.getLogger("")
        rootLogger.removeHandler(self.hdlr)
        rootLogger.setLevel(self.originalLevel)
        logging.shutdown()

    def test_singleString(self):
        """
        Test simple output, and default log level.
        """
        self.lp.msg("Hello, world.")
        self.assertIn("Hello, world.", self.out.getvalue())
        self.assertIn("INFO", self.out.getvalue())

    def test_errorString(self):
        """
        Test error output.
        """
        self.lp.msg(failure=failure.Failure(ValueError("That is bad.")), isError=True)
        self.assertIn("ERROR", self.out.getvalue())

    def test_formatString(self):
        """
        Test logging with a format.
        """
        self.lp.msg(format="%(bar)s oo %(foo)s", bar="Hello", foo="world")
        self.assertIn("Hello oo world", self.out.getvalue())

    def test_customLevel(self):
        """
        Test the logLevel keyword for customizing level used.
        """
        self.lp.msg("Spam egg.", logLevel=logging.DEBUG)
        self.assertIn("Spam egg.", self.out.getvalue())
        self.assertIn("DEBUG", self.out.getvalue())
        self.out.reset()
        self.lp.msg("Foo bar.", logLevel=logging.WARNING)
        self.assertIn("Foo bar.", self.out.getvalue())
        self.assertIn("WARNING", self.out.getvalue())

    def test_strangeEventDict(self):
        """
        Verify that an event dictionary which is not an error and has an empty
        message isn't recorded.
        """
        self.lp.msg(message='', isError=False)
        self.assertEqual(self.out.getvalue(), '')


class PythonLoggingIntegrationTestCase(unittest.TestCase):
    """
    Test integration of python logging bridge.
    """
    def test_startStopObserver(self):
        """
        Test that start and stop methods of the observer actually register
        and unregister to the log system.
        """
        oldAddObserver = log.addObserver
        oldRemoveObserver = log.removeObserver
        l = []
        try:
            log.addObserver = l.append
            log.removeObserver = l.remove
            obs = log.PythonLoggingObserver()
            obs.start()
            self.assertEqual(l[0], obs.emit)
            obs.stop()
            self.assertEqual(len(l), 0)
        finally:
            log.addObserver = oldAddObserver
            log.removeObserver = oldRemoveObserver

    def test_inheritance(self):
        """
        Test that we can inherit L{log.PythonLoggingObserver} and use super:
        that's basically a validation that L{log.PythonLoggingObserver} is
        new-style class.
        """
        class MyObserver(log.PythonLoggingObserver):
            def emit(self, eventDict):
                super(MyObserver, self).emit(eventDict)
        obs = MyObserver()
        l = []
        oldEmit = log.PythonLoggingObserver.emit
        try:
            log.PythonLoggingObserver.emit = l.append
            obs.emit('foo')
            self.assertEqual(len(l), 1)
        finally:
            log.PythonLoggingObserver.emit = oldEmit


class DefaultObserverTestCase(unittest.TestCase):
    """
    Test the default observer.
    """

    def test_failureLogger(self):
        """
        The reason argument passed to log.err() appears in the report
        generated by DefaultObserver.
        """
        from StringIO import StringIO

        obs = log.DefaultObserver()
        obs.stderr = StringIO()
        obs.start()

        reason = "The reason."
        log.err(Exception(), reason)
        errors = self.flushLoggedErrors()

        self.assertSubstring(reason, obs.stderr.getvalue())
        self.assertEqual(len(errors), 1)

        obs.stop()



class StdioOnnaStickTestCase(unittest.TestCase):
    """
    StdioOnnaStick should act like the normal sys.stdout object.
    """

    def setUp(self):
        self.resultLogs = []
        log.addObserver(self.resultLogs.append)


    def tearDown(self):
        log.removeObserver(self.resultLogs.append)


    def getLogMessages(self):
        return ["".join(d['message']) for d in self.resultLogs]


    def test_write(self):
        """
        Writing to a StdioOnnaStick instance results in Twisted log messages.

        Log messages are generated every time a '\n' is encountered.
        """
        stdio = log.StdioOnnaStick()
        stdio.write("Hello there\nThis is a test")
        self.assertEqual(self.getLogMessages(), ["Hello there"])
        stdio.write("!\n")
        self.assertEqual(self.getLogMessages(), ["Hello there", "This is a test!"])


    def test_metadata(self):
        """
        The log messages written by StdioOnnaStick have printed=1 keyword, and
        by default are not errors.
        """
        stdio = log.StdioOnnaStick()
        stdio.write("hello\n")
        self.assertEqual(self.resultLogs[0]['isError'], False)
        self.assertEqual(self.resultLogs[0]['printed'], True)


    def test_writeLines(self):
        """
        Writing lines to a StdioOnnaStick results in Twisted log messages.
        """
        stdio = log.StdioOnnaStick()
        stdio.writelines(["log 1", "log 2"])
        self.assertEqual(self.getLogMessages(), ["log 1", "log 2"])


    def test_print(self):
        """
        When StdioOnnaStick is set as sys.stdout, prints become log messages.
        """
        oldStdout = sys.stdout
        sys.stdout = log.StdioOnnaStick()
        self.addCleanup(setattr, sys, "stdout", oldStdout)
        print "This",
        print "is a test"
        self.assertEqual(self.getLogMessages(), ["This is a test"])


    def test_error(self):
        """
        StdioOnnaStick created with isError=True log messages as errors.
        """
        stdio = log.StdioOnnaStick(isError=True)
        stdio.write("log 1\n")
        self.assertEqual(self.resultLogs[0]['isError'], True)


    def test_unicode(self):
        """
        StdioOnnaStick converts unicode prints to strings, in order to be
        compatible with the normal stdout/stderr objects.
        """
        unicodeString = u"Hello, \N{VULGAR FRACTION ONE HALF} world."
        stdio = log.StdioOnnaStick(encoding="utf-8")
        self.assertEqual(stdio.encoding, "utf-8")
        stdio.write(unicodeString + u"\n")
        stdio.writelines([u"Also, " + unicodeString])
        oldStdout = sys.stdout
        sys.stdout = stdio
        self.addCleanup(setattr, sys, "stdout", oldStdout)
        # This should go to the log, utf-8 encoded too:
        print unicodeString
        self.assertEqual(self.getLogMessages(),
                         [unicodeString.encode("utf-8"),
                          (u"Also, " + unicodeString).encode("utf-8"),
                          unicodeString.encode("utf-8")])