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#!/usr/bin/env python
# Copyright 2020 The Pigweed Authors
#
# Licensed under the Apache License, Version 2.0 (the "License"); you may not
# use this file except in compliance with the License. You may obtain a copy of
# the License at
#
# https://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
# License for the specific language governing permissions and limitations under
# the License.
"""Contains the Python decoder tests and generates C++ decoder tests."""
from typing import Iterator, List, NamedTuple, Tuple
import unittest
from pw_build.generated_tests import Context, PyTest, TestGenerator, GroupOrTest
from pw_build.generated_tests import parse_test_generation_args
from pw_hdlc_lite.decode import Frame, FrameDecoder, FrameStatus, NO_ADDRESS
from pw_hdlc_lite.protocol import frame_check_sequence as fcs
def _encode(address: int, control: int, data: bytes) -> bytes:
frame = bytearray([address, control]) + data
frame += fcs(frame)
frame = frame.replace(b'\x7d', b'\x7d\x5d')
frame = frame.replace(b'\x7e', b'\x7d\x5e')
return b''.join([b'\x7e', frame, b'\x7e'])
class Expected(NamedTuple):
address: int
control: bytes
data: bytes
status: FrameStatus = FrameStatus.OK
def __eq__(self, other) -> bool:
"""Define == so an Expected and a Frame can be compared."""
return (self.address == other.address and self.control == other.control
and self.data == other.data and self.status is other.status)
_PARTIAL = fcs(b'\x0ACmsg\x5e')
_ESCAPED_FLAG_TEST_CASE = (
b'\x7e\x0ACmsg\x7d\x7e' + _PARTIAL + b'\x7e',
[
Expected(0xA, b'C', b'', FrameStatus.INCOMPLETE),
Expected(_PARTIAL[0], _PARTIAL[1:2], b'', FrameStatus.INCOMPLETE),
],
)
TEST_CASES: Tuple[GroupOrTest[Tuple[bytes, List[Expected]]], ...] = (
'Empty payload',
(_encode(0, 0, b''), [Expected(0, b'\0', b'')]),
(_encode(55, 0x99, b''), [Expected(55, b'\x99', b'')]),
(_encode(55, 0x99, b'') * 3, [Expected(55, b'\x99', b'')] * 3),
'Simple one-byte payload',
(_encode(0, 0, b'\0'), [Expected(0, b'\0', b'\0')]),
(_encode(123, 0, b'A'), [Expected(123, b'\0', b'A')]),
'Simple multi-byte payload',
(_encode(0, 0, b'Hello, world!'), [Expected(0, b'\0', b'Hello, world!')]),
(_encode(123, 0, b'\0\0\1\0\0'), [Expected(123, b'\0', b'\0\0\1\0\0')]),
'Escaped one-byte payload',
(_encode(1, 2, b'\x7e'), [Expected(1, b'\2', b'\x7e')]),
(_encode(1, 2, b'\x7d'), [Expected(1, b'\2', b'\x7d')]),
(_encode(1, 2, b'\x7e') + _encode(1, 2, b'\x7d'),
[Expected(1, b'\2', b'\x7e'),
Expected(1, b'\2', b'\x7d')]),
'Escaped address',
(_encode(0x7e, 0, b'A'), [Expected(0x7e, b'\0', b'A')]),
(_encode(0x7d, 0, b'B'), [Expected(0x7d, b'\0', b'B')]),
'Escaped control',
(_encode(0, 0x7e, b'C'), [Expected(0, b'\x7e', b'C')]),
(_encode(0, 0x7d, b'D'), [Expected(0, b'\x7d', b'D')]),
'Escaped address and control',
(_encode(0x7e, 0x7d, b'E'), [Expected(0x7e, b'\x7d', b'E')]),
(_encode(0x7d, 0x7e, b'F'), [Expected(0x7d, b'\x7e', b'F')]),
(_encode(0x7e, 0x7e, b'\x7e'), [Expected(0x7e, b'\x7e', b'\x7e')]),
'Multiple frames separated by single flag',
(_encode(0, 0, b'A')[:-1] + _encode(1, 2, b'123'),
[Expected(0, b'\0', b'A'),
Expected(1, b'\2', b'123')]),
(_encode(0xff, 0, b'Yo')[:-1] * 3 + b'\x7e',
[Expected(0xff, b'\0', b'Yo')] * 3),
'Ignore empty frames',
(b'\x7e\x7e', []),
(b'\x7e' * 10, []),
(b'\x7e\x7e' + _encode(1, 2, b'3') + b'\x7e' * 5,
[Expected(1, b'\2', b'3')]),
(b'\x7e' * 10 + _encode(1, 2, b':O') + b'\x7e' * 3 + _encode(3, 4, b':P'),
[Expected(1, b'\2', b':O'),
Expected(3, b'\4', b':P')]),
'Cannot escape flag',
(b'\x7e\xAA\x7d\x7e\xab\x00Hello' + fcs(b'\xab\0Hello') + b'\x7e', [
Expected(0xAA, b'', b'', FrameStatus.INCOMPLETE),
Expected(0xab, b'\0', b'Hello'),
]),
_ESCAPED_FLAG_TEST_CASE,
'Frame too short',
(b'\x7e1\x7e', [Expected(ord('1'), b'', b'', FrameStatus.INCOMPLETE)]),
(b'\x7e12\x7e', [Expected(ord('1'), b'2', b'', FrameStatus.INCOMPLETE)]),
(b'\x7e12345\x7e', [Expected(ord('1'), b'2', b'',
FrameStatus.INCOMPLETE)]),
'Incorrect frame check sequence',
(b'\x7e123456\x7e',
[Expected(ord('1'), b'2', b'', FrameStatus.FCS_MISMATCH)]),
(b'\x7e\1\2msg\xff\xff\xff\xff\x7e',
[Expected(0x1, b'\2', b'msg', FrameStatus.FCS_MISMATCH)]),
(_encode(0xA, 0xB, b'???')[:-2] + _encode(1, 2, b'def'), [
Expected(0xA, b'\x0B', b'??', FrameStatus.FCS_MISMATCH),
Expected(1, b'\2', b'def'),
]),
'Invalid escape in address',
(b'\x7e\x7d\x7d\0' + fcs(b'\x5d\0') + b'\x7e',
[Expected(0,
fcs(b'\x5d\0')[0:1], b'', FrameStatus.INVALID_ESCAPE)]),
'Invalid escape in control',
(b'\x7e\0\x7d\x7d' + fcs(b'\0\x5d') + b'\x7e',
[Expected(0,
fcs(b'\0\x5d')[0:1], b'', FrameStatus.INVALID_ESCAPE)]),
'Invalid escape in data',
(b'\x7e\0\1\x7d\x7d' + fcs(b'\0\1\x5d') + b'\x7e',
[Expected(0, b'\1', b'', FrameStatus.INVALID_ESCAPE)]),
'Frame ends with escape',
(b'\x7e\x7d\x7e', [Expected(NO_ADDRESS, b'', b'',
FrameStatus.INCOMPLETE)]),
(b'\x7e\1\x7d\x7e', [Expected(1, b'', b'', FrameStatus.INCOMPLETE)]),
(b'\x7e\1\2abc\x7d\x7e', [Expected(1, b'\2', b'',
FrameStatus.INCOMPLETE)]),
(b'\x7e\1\2abcd\x7d\x7e',
[Expected(1, b'\2', b'', FrameStatus.INCOMPLETE)]),
(b'\x7e\1\2abcd1234\x7d\x7e',
[Expected(1, b'\2', b'abcd', FrameStatus.INCOMPLETE)]),
'Inter-frame data is only escapes',
(b'\x7e\x7d\x7e\x7d\x7e', [
Expected(NO_ADDRESS, b'', b'', FrameStatus.INCOMPLETE),
Expected(NO_ADDRESS, b'', b'', FrameStatus.INCOMPLETE),
]),
(b'\x7e\x7d\x7d\x7e\x7d\x7d\x7e', [
Expected(NO_ADDRESS, b'', b'', FrameStatus.INVALID_ESCAPE),
Expected(NO_ADDRESS, b'', b'', FrameStatus.INVALID_ESCAPE),
]),
'Data before first flag',
(b'\0\1' + fcs(b'\0\1'), []),
(b'\0\1' + fcs(b'\0\1') + b'\x7e',
[Expected(0, b'\1', b'', FrameStatus.INCOMPLETE)]),
'No frames emitted until flag',
(_encode(1, 2, b'3')[:-1], []),
(b'\x7e' + _encode(1, 2, b'3')[1:-1] * 2, []),
) # yapf: disable
# Formatting for the above tuple is very slow, so disable yapf.
_TESTS = TestGenerator(TEST_CASES)
def _expected(frames: List[Frame]) -> Iterator[str]:
for i, frame in enumerate(frames, 1):
if frame.ok():
yield f' Frame(kDecodedFrame{i:02}),'
else:
yield f' Status::DATA_LOSS, // Frame {i}'
_CPP_HEADER = """\
#include "pw_hdlc_lite/decoder.h"
#include <array>
#include <cstddef>
#include <variant>
#include "gtest/gtest.h"
#include "pw_bytes/array.h"
namespace pw::hdlc_lite {
namespace {
"""
_CPP_FOOTER = """\
} // namespace
} // namespace pw::hdlc_lite"""
def _cpp_test(ctx: Context) -> Iterator[str]:
"""Generates a C++ test for the provided test data."""
data, _ = ctx.test_case
frames = list(FrameDecoder().process(data))
data_bytes = ''.join(rf'\x{byte:02x}' for byte in data)
yield f'TEST(Decoder, {ctx.cc_name()}) {{'
yield f' static constexpr auto kData = bytes::String("{data_bytes}");\n'
for i, frame in enumerate(frames, 1):
if frame.status is FrameStatus.OK:
frame_bytes = ''.join(rf'\x{byte:02x}' for byte in frame.raw)
yield (f' static constexpr auto kDecodedFrame{i:02} = '
f'bytes::String("{frame_bytes}");')
else:
yield f' // Frame {i}: {frame.status.value}'
yield ''
expected = '\n'.join(_expected(frames)) or ' // No frames'
decoder_size = max(len(data), 8) # Make sure large enough for a frame
yield f"""\
DecoderBuffer<{decoder_size}> decoder;
static constexpr std::array<std::variant<Frame, Status>, {len(frames)}> kExpected = {{
{expected}
}};
size_t decoded_frames = 0;
decoder.Process(kData, [&](const Result<Frame>& result) {{
ASSERT_LT(decoded_frames++, kExpected.size());
auto& expected = kExpected[decoded_frames - 1];
if (std::holds_alternative<Status>(expected)) {{
EXPECT_EQ(Status::DATA_LOSS, result.status());
}} else {{
ASSERT_EQ(Status::OK, result.status());
const Frame& decoded_frame = result.value();
const Frame& expected_frame = std::get<Frame>(expected);
EXPECT_EQ(expected_frame.address(), decoded_frame.address());
EXPECT_EQ(expected_frame.control(), decoded_frame.control());
ASSERT_EQ(expected_frame.data().size(), decoded_frame.data().size());
EXPECT_EQ(std::memcmp(expected_frame.data().data(),
decoded_frame.data().data(),
expected_frame.data().size()),
0);
}}
}});
EXPECT_EQ(decoded_frames, kExpected.size());
}}"""
def _define_py_test(ctx: Context) -> PyTest:
data, expected_frames = ctx.test_case
def test(self) -> None:
# Decode in one call
self.assertEqual(expected_frames,
list(FrameDecoder().process(data)),
msg=f'{ctx.group}: {data!r}')
# Decode byte-by-byte
decoder = FrameDecoder()
decoded_frames: List[Frame] = []
for i in range(len(data)):
decoded_frames += decoder.process(data[i:i + 1])
self.assertEqual(expected_frames,
decoded_frames,
msg=f'{ctx.group} (byte-by-byte): {data!r}')
return test
# Class that tests all cases in TEST_CASES.
DecoderTest = _TESTS.python_tests('DecoderTest', _define_py_test)
if __name__ == '__main__':
args = parse_test_generation_args()
if args.generate_cc_test:
_TESTS.cc_tests(args.generate_cc_test, _cpp_test, _CPP_HEADER,
_CPP_FOOTER)
else:
unittest.main()
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