/brz/remove-bazaar

# Copyright (C) 2011 Canonical Ltd

#

# 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

"""Tests for our estimation of compressed content."""

import zlib

import hashlib

from .. import (

    estimate_compressed_size,

    tests,

    )

class TestZLibEstimator(tests.TestCase):

    def get_slightly_random_content(self, length, seed=b''):

        """We generate some hex-data that can be seeded.

        The output should be deterministic, but the data stream is effectively

        random.

        """

        h = hashlib.md5(seed)

        hex_content = []

        count = 0

        while count < length:

            b = h.hexdigest().encode('ascii')

            hex_content.append(b)

            h.update(b)

            count += len(b)

        return b''.join(hex_content)[:length]

    def test_adding_content(self):

        ze = estimate_compressed_size.ZLibEstimator(32000)

        raw_data = self.get_slightly_random_content(60000)

        block_size = 1000

        for start in range(0, len(raw_data), block_size):

            ze.add_content(raw_data[start:start + block_size])

            if ze.full():

                break

        # Practise showed that 'start' was 56000. However, zlib is a bit

        # platform dependent, so give it +/- 5%.

        self.assertTrue(54000 <= start <= 58000,

                        "Unexpected amount of raw data added: %d bytes" % (start,))

        # The real compression should be 'close' to 32000, real measurement was

        # 32401

        raw_comp = zlib.compress(raw_data[:start])

        self.assertTrue(31000 < len(raw_comp) < 33000,

                        "Unexpected compressed size: %d bytes" % (len(raw_comp),))

    def test_adding_more_content(self):

        ze = estimate_compressed_size.ZLibEstimator(64000)

        raw_data = self.get_slightly_random_content(150000)

        block_size = 1000

        for start in range(0, len(raw_data), block_size):

            ze.add_content(raw_data[start:start + block_size])

            if ze.full():

                break

        # Practise showed that 'start' was 112000

        self.assertTrue(110000 <= start <= 114000,

                        "Unexpected amount of raw data added: %d bytes" % (start,))

        # The real compression should be 'close' to 32000, real measurement was

        # 32401

        raw_comp = zlib.compress(raw_data[:start])

        self.assertTrue(63000 < len(raw_comp) < 65000,

                        "Unexpected compressed size: %d bytes" % (len(raw_comp),))