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# 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 bzrlib import (
estimate_compressed_size,
tests,
)
class TestZLibEstimator(tests.TestCase):
def get_slightly_random_content(self, length, seed=''):
"""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()
hex_content.append(b)
h.update(b)
count += len(b)
return ''.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 xrange(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 xrange(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),))
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