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1import logging
2import collections
3
4from .case import _BaseTestCaseContext
5
6
7_LoggingWatcher = collections.namedtuple("_LoggingWatcher",
8                                         ["records", "output"])
9
10class _CapturingHandler(logging.Handler):
11    """
12    A logging handler capturing all (raw and formatted) logging output.
13    """
14
15    def __init__(self):
16        logging.Handler.__init__(self)
17        self.watcher = _LoggingWatcher([], [])
18
19    def flush(self):
20        pass
21
22    def emit(self, record):
23        self.watcher.records.append(record)
24        msg = self.format(record)
25        self.watcher.output.append(msg)
26
27
28class _AssertLogsContext(_BaseTestCaseContext):
29    """A context manager used to implement TestCase.assertLogs()."""
30
31    LOGGING_FORMAT = "%(levelname)s:%(name)s:%(message)s"
32
33    def __init__(self, test_case, logger_name, level):
34        _BaseTestCaseContext.__init__(self, test_case)
35        self.logger_name = logger_name
36        if level:
37            self.level = logging._nameToLevel.get(level, level)
38        else:
39            self.level = logging.INFO
40        self.msg = None
41
42    def __enter__(self):
43        if isinstance(self.logger_name, logging.Logger):
44            logger = self.logger = self.logger_name
45        else:
46            logger = self.logger = logging.getLogger(self.logger_name)
47        formatter = logging.Formatter(self.LOGGING_FORMAT)
48        handler = _CapturingHandler()
49        handler.setFormatter(formatter)
50        self.watcher = handler.watcher
51        self.old_handlers = logger.handlers[:]
52        self.old_level = logger.level
53        self.old_propagate = logger.propagate
54        logger.handlers = [handler]
55        logger.setLevel(self.level)
56        logger.propagate = False
57        return handler.watcher
58
59    def __exit__(self, exc_type, exc_value, tb):
60        self.logger.handlers = self.old_handlers
61        self.logger.propagate = self.old_propagate
62        self.logger.setLevel(self.old_level)
63        if exc_type is not None:
64            # let unexpected exceptions pass through
65            return False
66        if len(self.watcher.records) == 0:
67            self._raiseFailure(
68                "no logs of level {} or higher triggered on {}"
69                .format(logging.getLevelName(self.level), self.logger.name))
70