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bzrlib/tests/test_chunk_writer.py
 
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# Copyright (C) 2008 Canonical Ltd
 
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#
 
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# This program is free software; you can redistribute it and/or modify
 
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# it under the terms of the GNU General Public License as published by
 
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# the Free Software Foundation; either version 2 of the License, or
 
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# (at your option) any later version.
 
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#
 
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# This program is distributed in the hope that it will be useful,
 
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# but WITHOUT ANY WARRANTY; without even the implied warranty of
 
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 
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# GNU General Public License for more details.
 
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#
 
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# You should have received a copy of the GNU General Public License
 
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# along with this program; if not, write to the Free Software
 
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# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307  USA
 
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#
 
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"""Tests for writing fixed size chunks with compression."""
 
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import zlib
 
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from bzrlib import chunk_writer
 
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from bzrlib.tests import TestCaseWithTransport
 
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class TestWriter(TestCaseWithTransport):
 
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    def check_chunk(self, bytes_list, size):
 
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        bytes = ''.join(bytes_list)
 
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        self.assertEqual(size, len(bytes))
 
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        return zlib.decompress(bytes)
 
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    def test_chunk_writer_empty(self):
 
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        writer = chunk_writer.ChunkWriter(4096)
 
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        bytes_list, unused, padding = writer.finish()
 
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        node_bytes = self.check_chunk(bytes_list, 4096)
 
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        self.assertEqual("", node_bytes)
 
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        self.assertEqual(None, unused)
 
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        # Only a zlib header.
 
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        self.assertEqual(4088, padding)
 
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    def test_some_data(self):
 
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        writer = chunk_writer.ChunkWriter(4096)
 
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        writer.write("foo bar baz quux\n")
 
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        bytes_list, unused, padding = writer.finish()
 
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        node_bytes = self.check_chunk(bytes_list, 4096)
 
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        self.assertEqual("foo bar baz quux\n", node_bytes)
 
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        self.assertEqual(None, unused)
 
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        # More than just the header..
 
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        self.assertEqual(4073, padding)
 
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    def test_too_much_data_does_not_exceed_size(self):
 
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        # Generate enough data to exceed 4K
 
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        lines = []
 
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        for group in range(48):
 
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            offset = group * 50
 
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            numbers = range(offset, offset + 50)
 
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            # Create a line with this group
 
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            lines.append(''.join(map(str, numbers)) + '\n')
 
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        writer = chunk_writer.ChunkWriter(4096)
 
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        for idx, line in enumerate(lines):
 
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            if writer.write(line):
 
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                self.assertEqual(46, idx)
 
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                break
 
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        bytes_list, unused, _ = writer.finish()
 
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        node_bytes = self.check_chunk(bytes_list, 4096)
 
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        # the first 46 lines should have been added
 
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        expected_bytes = ''.join(lines[:46])
 
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        self.assertEqualDiff(expected_bytes, node_bytes)
 
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        # And the line that failed should have been saved for us
 
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        self.assertEqual(lines[46], unused)
 
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    def test_too_much_data_preserves_reserve_space(self):
 
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        # Generate enough data to exceed 4K
 
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        lines = []
 
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        for group in range(48):
 
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            offset = group * 50
 
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            numbers = range(offset, offset + 50)
 
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            # Create a line with this group
 
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            lines.append(''.join(map(str, numbers)) + '\n')
 
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        writer = chunk_writer.ChunkWriter(4096, 256)
 
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        for idx, line in enumerate(lines):
 
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            if writer.write(line):
 
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                self.assertEqual(44, idx)
 
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                break
 
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        else:
 
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            self.fail('We were able to write all lines')
 
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        self.assertFalse(writer.write("A"*256, reserved=True))
 
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        bytes_list, unused, _ = writer.finish()
 
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        node_bytes = self.check_chunk(bytes_list, 4096)
 
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        # the first 44 lines should have been added
 
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        expected_bytes = ''.join(lines[:44]) + "A"*256
 
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        self.assertEqualDiff(expected_bytes, node_bytes)
 
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        # And the line that failed should have been saved for us
 
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        self.assertEqual(lines[44], unused)