cloudcomputinghust/CAL

# NOTE(mriedem): This is needed for importing from fixtures.
from __future__ import absolute_import

import logging as std_logging
import os

import fixtures

_TRUE_VALUES = ('True', 'true', '1', 'yes')


class NullHandler(std_logging.Handler):

    """custom default NullHandler to attempt to format the record.
    Used in conjunction with
    log_fixture.get_logging_handle_error_fixture to detect formatting errors in
    debug level logs without saving the logs.
    """

    def handle(self, record):
        self.format(record)

    def emit(self, record):
        pass

    def createLock(self):
        self.lock = None


class StandardLogging(fixtures.Fixture):

    """Setup Logging redirection for tests.
    There are a number of things we want to handle with logging in tests:
    * Redirect the logging to somewhere that we can test or dump it later.
    * Ensure that as many DEBUG messages as possible are actually
       executed, to ensure they are actually syntactically valid (they
       often have not been).
    * Ensure that we create useful output for tests that doesn't
      overwhelm the testing system (which means we can't capture the
      100 MB of debug logging on every run).
    To do this we create a logger fixture at the root level, which
    defaults to INFO and create a Null Logger at DEBUG which lets
    us execute log messages at DEBUG but not keep the output.
    To support local debugging OS_DEBUG=True can be set in the
    environment, which will print out the full debug logging.
    There are also a set of overrides for particularly verbose
    modules to be even less than INFO.
    """

    def setUp(self):
        super(StandardLogging, self).setUp()

        # set root logger to debug
        root = std_logging.getLogger()
        root.setLevel(std_logging.DEBUG)

        # supports collecting debug level for local runs
        if os.environ.get('OS_DEBUG') in _TRUE_VALUES:
            level = std_logging.DEBUG
        else:
            level = std_logging.INFO

        # Collect logs
        fs = '%(asctime)s %(levelname)s [%(name)s] %(message)s'
        self.logger = self.useFixture(
            fixtures.FakeLogger(format=fs, level=None))
        # TODO(sdague): why can't we send level through the fake
        # logger? Tests prove that it breaks, but it's worth getting
        # to the bottom of.
        root.handlers[0].setLevel(level)

        if level > std_logging.DEBUG:
            # Just attempt to format debug level logs, but don't save them
            handler = NullHandler()
            self.useFixture(fixtures.LogHandler(handler, nuke_handlers=False))
            handler.setLevel(std_logging.DEBUG)

            # Don't log every single DB migration step
            std_logging.getLogger(
                'migrate.versioning.api').setLevel(std_logging.WARNING)


def copy_and_update_dict(src_dict, diffs):
    """Returns a copy of src_dict, updated with the new key-value
       pairs in diffs."""
    dest_dict = dict(src_dict)
    dest_dict.update(diffs)
    return dest_dict