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// Copyright 2017 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include "net/tools/huffman_trie/bit_writer.h"
#include "testing/gmock/include/gmock/gmock.h"
#include "testing/gtest/include/gtest/gtest.h"
namespace net::huffman_trie {
namespace {
// Test that single bits are written to the buffer correctly.
TEST(BitWriterTest, WriteBit) {
BitWriter writer;
EXPECT_EQ(0U, writer.position());
EXPECT_EQ(0U, writer.bytes().size());
writer.WriteBit(0);
EXPECT_EQ(1U, writer.position());
writer.WriteBit(1);
writer.WriteBit(0);
writer.WriteBit(1);
writer.WriteBit(0);
writer.WriteBit(1);
writer.WriteBit(0);
writer.WriteBit(1);
EXPECT_EQ(8U, writer.position());
writer.WriteBit(0);
EXPECT_EQ(9U, writer.position());
writer.WriteBit(1);
writer.WriteBit(0);
EXPECT_EQ(11U, writer.position());
// Flush should pad the current byte with zero's until it's full.
writer.Flush();
// The writer should have 2 bytes now even though we only wrote 11 bits.
EXPECT_EQ(16U, writer.position());
// 0 + 1 + 0 + 1 + 0 + 1 + 0 + 1 + 0 + 1 + 0 + 00000 (padding) = 0x5540.
EXPECT_THAT(writer.bytes(), testing::ElementsAre(0x55, 0x40));
}
// Test that when multiple bits are written to the buffer, they are appended
// correctly.
TEST(BitWriterTest, WriteBits) {
BitWriter writer;
// 0xAA is 10101010 in binary. WritBits will write the n least significant
// bits where n is given as the second parameter.
writer.WriteBits(0xAA, 1);
EXPECT_EQ(1U, writer.position());
writer.WriteBits(0xAA, 2);
EXPECT_EQ(3U, writer.position());
writer.WriteBits(0xAA, 3);
EXPECT_EQ(6U, writer.position());
writer.WriteBits(0xAA, 2);
EXPECT_EQ(8U, writer.position());
writer.WriteBits(0xAA, 2);
EXPECT_EQ(10U, writer.position());
// Flush should pad the current byte with zero's until it's full.
writer.Flush();
// The writer should have 2 bytes now even though we only wrote 10 bits.
EXPECT_EQ(16U, writer.position());
// 0 + 10 + 010 + 10 + 10 + 000000 (padding) = 0x4A80
EXPECT_THAT(writer.bytes(), testing::ElementsAre(0x4A, 0x80));
}
// Test that buffering works correct when the methods are mixed.
TEST(BitWriterTest, WriteBoth) {
BitWriter writer;
// 0xAA is 10101010 in binary. WritBits will write the n least significant
// bits where n is given as the second parameter.
writer.WriteBits(0xAA, 1);
EXPECT_EQ(1U, writer.position());
writer.WriteBit(1);
writer.WriteBits(0xAA, 2);
EXPECT_EQ(4U, writer.position());
writer.WriteBits(0xAA, 3);
EXPECT_EQ(7U, writer.position());
writer.WriteBit(1);
EXPECT_EQ(8U, writer.position());
writer.WriteBits(0xAA, 2);
writer.WriteBit(0);
EXPECT_EQ(11U, writer.position());
// Flush should pad the current byte with zero's until it's full.
writer.Flush();
// The writer should have 2 bytes now even though we only wrote 10 bits.
EXPECT_EQ(16U, writer.position());
// 0 + 1 + 10 + 010 + 1 + 10 + 0 + 00000 (padding) = 0x6580
EXPECT_THAT(writer.bytes(), testing::ElementsAre(0x65, 0x80));
}
} // namespace
} // namespace net::huffman_trie
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