contrib/python-zstandard/tests/test_data_structures.py

githelp: clean up reflog help

This referenced commands that don't exist in core. The new help
isn't great since it references an experimental extension. But
it is better than nothing.

While we're here, also add test coverage.

Differential Revision: https://phab.mercurial-scm.org/D1727

try:
    import unittest2 as unittest
except ImportError:
    import unittest

import zstd

from . common import (
    make_cffi,
)


@make_cffi
class TestCompressionParameters(unittest.TestCase):
    def test_init_bad_arg_type(self):
        with self.assertRaises(TypeError):
            zstd.CompressionParameters()

        with self.assertRaises(TypeError):
            zstd.CompressionParameters(0, 1)

    def test_bounds(self):
        zstd.CompressionParameters(zstd.WINDOWLOG_MIN,
                                   zstd.CHAINLOG_MIN,
                                   zstd.HASHLOG_MIN,
                                   zstd.SEARCHLOG_MIN,
                                   zstd.SEARCHLENGTH_MIN + 1,
                                   zstd.TARGETLENGTH_MIN,
                                   zstd.STRATEGY_FAST)

        zstd.CompressionParameters(zstd.WINDOWLOG_MAX,
                                   zstd.CHAINLOG_MAX,
                                   zstd.HASHLOG_MAX,
                                   zstd.SEARCHLOG_MAX,
                                   zstd.SEARCHLENGTH_MAX - 1,
                                   zstd.TARGETLENGTH_MAX,
                                   zstd.STRATEGY_BTOPT)

    def test_get_compression_parameters(self):
        p = zstd.get_compression_parameters(1)
        self.assertIsInstance(p, zstd.CompressionParameters)

        self.assertEqual(p.window_log, 19)

    def test_members(self):
        p = zstd.CompressionParameters(10, 6, 7, 4, 5, 8, 1)
        self.assertEqual(p.window_log, 10)
        self.assertEqual(p.chain_log, 6)
        self.assertEqual(p.hash_log, 7)
        self.assertEqual(p.search_log, 4)
        self.assertEqual(p.search_length, 5)
        self.assertEqual(p.target_length, 8)
        self.assertEqual(p.strategy, 1)

    def test_estimated_compression_context_size(self):
        p = zstd.CompressionParameters(20, 16, 17,  1,  5, 16, zstd.STRATEGY_DFAST)

        # 32-bit has slightly different values from 64-bit.
        self.assertAlmostEqual(p.estimated_compression_context_size(), 1287076,
                               delta=110)


@make_cffi
class TestFrameParameters(unittest.TestCase):
    def test_invalid_type(self):
        with self.assertRaises(TypeError):
            zstd.get_frame_parameters(None)

        with self.assertRaises(TypeError):
            zstd.get_frame_parameters(u'foobarbaz')

    def test_invalid_input_sizes(self):
        with self.assertRaisesRegexp(zstd.ZstdError, 'not enough data for frame'):
            zstd.get_frame_parameters(b'')

        with self.assertRaisesRegexp(zstd.ZstdError, 'not enough data for frame'):
            zstd.get_frame_parameters(zstd.FRAME_HEADER)

    def test_invalid_frame(self):
        with self.assertRaisesRegexp(zstd.ZstdError, 'Unknown frame descriptor'):
            zstd.get_frame_parameters(b'foobarbaz')

    def test_attributes(self):
        params = zstd.get_frame_parameters(zstd.FRAME_HEADER + b'\x00\x00')
        self.assertEqual(params.content_size, 0)
        self.assertEqual(params.window_size, 1024)
        self.assertEqual(params.dict_id, 0)
        self.assertFalse(params.has_checksum)

        # Lowest 2 bits indicate a dictionary and length. Here, the dict id is 1 byte.
        params = zstd.get_frame_parameters(zstd.FRAME_HEADER + b'\x01\x00\xff')
        self.assertEqual(params.content_size, 0)
        self.assertEqual(params.window_size, 1024)
        self.assertEqual(params.dict_id, 255)
        self.assertFalse(params.has_checksum)

        # Lowest 3rd bit indicates if checksum is present.
        params = zstd.get_frame_parameters(zstd.FRAME_HEADER + b'\x04\x00')
        self.assertEqual(params.content_size, 0)
        self.assertEqual(params.window_size, 1024)
        self.assertEqual(params.dict_id, 0)
        self.assertTrue(params.has_checksum)

        # Upper 2 bits indicate content size.
        params = zstd.get_frame_parameters(zstd.FRAME_HEADER + b'\x40\x00\xff\x00')
        self.assertEqual(params.content_size, 511)
        self.assertEqual(params.window_size, 1024)
        self.assertEqual(params.dict_id, 0)
        self.assertFalse(params.has_checksum)

        # Window descriptor is 2nd byte after frame header.
        params = zstd.get_frame_parameters(zstd.FRAME_HEADER + b'\x00\x40')
        self.assertEqual(params.content_size, 0)
        self.assertEqual(params.window_size, 262144)
        self.assertEqual(params.dict_id, 0)
        self.assertFalse(params.has_checksum)

        # Set multiple things.
        params = zstd.get_frame_parameters(zstd.FRAME_HEADER + b'\x45\x40\x0f\x10\x00')
        self.assertEqual(params.content_size, 272)
        self.assertEqual(params.window_size, 262144)
        self.assertEqual(params.dict_id, 15)
        self.assertTrue(params.has_checksum)