# Copyright (c) 2004 Canonical Limited
#       Author: Robert Collins <robert.collins@canonical.com>
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program; if not, write to the Free Software
# Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
#

import logging
import unittest


class LogCollector(logging.Handler):
    def __init__(self):
        logging.Handler.__init__(self)
        self.records=[]
    def emit(self, record):
        self.records.append(record.getMessage())


def makeCollectingLogger():
    """I make a logger instance that collects its logs for programmatic analysis
    -> (logger, collector)"""
    logger=logging.Logger("collector")
    handler=LogCollector()
    handler.setFormatter(logging.Formatter("%(levelname)s: %(message)s"))
    logger.addHandler(handler)
    return logger, handler


def visitTests(suite, visitor):
    """A foreign method for visiting the tests in a test suite."""
    if isinstance(suite, unittest.TestCase):
        visitor.visitCase(suite)
        return
    for test in suite._tests:
        #Abusing types to avoid monkey patching unittest.TestCase.
        # Maybe that would be better?
        try:
            test.visit(visitor)
        except AttributeError:
            if isinstance(test, unittest.TestCase):
                visitor.visitCase(test)
            elif isinstance(test, unittest.TestSuite):
                visitor.visitSuite(test)
                visitTests(test, visitor)
            else:
                print("unvisitable non-unittest.TestCase element %r (%r)" % (test, test.__class__))


class TestSuite(unittest.TestSuite):
    """I am an extended TestSuite with a visitor interface.
    This is primarily to allow filtering of tests - and suites or
    more in the future. An iterator of just tests wouldn't scale..."""

    def visit(self, visitor):
        """visit the composite. Visiting is depth-first.
        current callbacks are visitSuite and visitCase."""
        visitor.visitSuite(self)
        visitTests(self, visitor)


class TestLoader(unittest.TestLoader):
    """Custome TestLoader to set the right TestSuite class."""
    suiteClass = TestSuite

class TestVisitor(object):
    """A visitor for Tests"""
    def visitSuite(self, aTestSuite):
        pass
    def visitCase(self, aTestCase):
        pass
