testhdlr.py

#!/usr/bin/env python
# Copyright (C) 2010 Vinay Sajip. All Rights Reserved.
#
# Permission to use, copy, modify, and distribute this software and its
# documentation for any purpose and without fee is hereby granted,
# provided that the above copyright notice appear in all copies and that
# both that copyright notice and this permission notice appear in
# supporting documentation, and that the name of Vinay Sajip
# not be used in advertising or publicity pertaining to distribution
# of the software without specific, written prior permission.
# VINAY SAJIP DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE, INCLUDING
# ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL
# VINAY SAJIP BE LIABLE FOR ANY SPECIAL, INDIRECT OR CONSEQUENTIAL DAMAGES OR
# ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER
# IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT
# OF OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
#
import logging
from logging.handlers import BufferingHandler
import unittest

class TestHandler(BufferingHandler):
    def __init__(self, matcher):
        # BufferingHandler takes a "capacity" argument
        # so as to know when to flush. As we're overriding
        # shouldFlush anyway, we can set a capacity of zero.
        # You can call flush() manually to clear out the
        # buffer.
        BufferingHandler.__init__(self, 0)
        self.matcher = matcher

    def shouldFlush(self):
        return False

    def emit(self, record):
        self.format(record)
        self.buffer.append(record.__dict__)

    def matches(self, **kwargs):
        """
        Look for a saved dict whose keys/values match the supplied arguments.
        """
        result = False
        for d in self.buffer:
            if self.matcher.matches(d, **kwargs):
                result = True
                break
        return result

class Matcher(object):

    _partial_matches = ('msg', 'message')

    def matches(self, d, **kwargs):
        """
        Try to match a single dict with the supplied arguments.

        Keys whose values are strings and which are in self._partial_matches
        will be checked for partial (i.e. substring) matches. You can extend
        this scheme to (for example) do regular expression matching, etc.
        """
        result = True
        for k in kwargs:
            v = kwargs[k]
            dv = d.get(k)
            if not self.match_value(k, dv, v):
                result = False
                break
        return result

    def match_value(self, k, dv, v):
        """
        Try to match a single stored value (dv) with a supplied value (v).
        """
        if type(v) != type(dv):
            result = False
        elif type(dv) is not str or k not in self._partial_matches:
            result = (v == dv)
        else:
            result = dv.find(v) >= 0
        return result

class LoggingTest(unittest.TestCase):
    def setUp(self):
        self.handler = h = TestHandler(Matcher())
        self.logger = l = logging.getLogger()
        l.addHandler(h)
        
    def tearDown(self):
        self.logger.removeHandler(self.handler)
        self.handler.close()
        
    def test_simple(self):
        "Simple test of logging test harness."
        # Just as a demo, let's log some messages.
        # Only one should show up in the log.
        self.logger.debug("This won't show up.")
        self.logger.info("Neither will this.")
        self.logger.warning("But this will.")
        h = self.handler
        self.assertTrue(h.matches(levelno=logging.WARNING))
        self.assertFalse(h.matches(levelno=logging.DEBUG))
        self.assertFalse(h.matches(levelno=logging.INFO))

    def test_partial(self):
        "Test of partial matching in logging test harness."
        # Just as a demo, let's log some messages.
        # Only one should show up in the log.
        self.logger.debug("This won't show up.")
        self.logger.info("Neither will this.")
        self.logger.warning("But this will.")
        h = self.handler
        self.assertTrue(h.matches(msg="ut th")) # from "But this will"
        self.assertTrue(h.matches(message="ut th")) # from "But this will"
        self.assertFalse(h.matches(message="either"))
        self.assertFalse(h.matches(message="won't"))

    def test_multiple(self):
        "Test of matching multiple values in logging test harness."
        # Just as a demo, let's log some messages.
        # Only one should show up in the log.
        self.logger.debug("This won't show up.")
        self.logger.info("Neither will this.")
        self.logger.warning("But this will.")
        self.logger.error("And so will this.")
        h = self.handler
        self.assertTrue(h.matches(levelno=logging.WARNING,
                                  funcName='test_multiple'))
        self.assertTrue(h.matches(levelno=logging.ERROR,
                                  funcName='test_multiple'))
        self.assertFalse(h.matches(levelno=logging.INFO))

if __name__ == '__main__':
    unittest.main()