Add unittests for different transport security state generator components.

net/tools/transport_security_state_generator/trie/trie_bit_buffer_unittest.cc

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "net/tools/transport_security_state_generator/trie/trie_bit_buffer.h"
+#include "net/tools/transport_security_state_generator/bit_writer.h"
+#include "net/tools/transport_security_state_generator/huffman/huffman_builder.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace net {
+
+namespace transport_security_state {
+
+// Test writing single bits to the buffer.
+TEST(TrieBitBufferTest, WriteBit) {
+  TrieBitBuffer buffer;
+
+  buffer.WriteBit(0);
+  buffer.WriteBit(1);
+  buffer.WriteBit(0);
+  buffer.WriteBit(1);
+  buffer.WriteBit(0);
+  buffer.WriteBit(1);
+  buffer.WriteBit(0);
+  buffer.WriteBit(1);
+
+  BitWriter writer;
+  buffer.WriteToBitWriter(&writer);
+
+  writer.Flush();
+
+  // 0 + 1 + 0 + 1 + 0 + 1 + 0 + 1 = 0x55
+  EXPECT_THAT(writer.bytes(), testing::ElementsAre(0x55, 0x0));

[martijnc, 2017/03/26 18:53:16]

This looks a little weird (padding with an entire \0 byte) but the behavior is
copied from the original Go code. Not sure if this was intentional or not but I
left the behavior as it was to avoid introducing unintentional behavior changes.

In practice this could add an additional byte to the end of the generated blob
if the length is an exact multiple of 8. This extra byte would never be accessed
if the rest of the structure is correct.

+  EXPECT_EQ(16U, writer.position());
+
+  buffer.WriteBit(0);
+  buffer.WriteBit(1);
+  buffer.WriteBit(0);
+
+  BitWriter writer2;
+  buffer.WriteToBitWriter(&writer2);
+  EXPECT_EQ(11U, writer2.position());
+
+  writer2.Flush();
+
+  // 0 + 1 + 0 + 1 + 0 + 1 + 0 + 1 + 0 + 1 + 0 + 00000 (padding) = 0x5540.
+  EXPECT_THAT(writer2.bytes(), testing::ElementsAre(0x55, 0x40));
+}
+
+// Test writing multiple bits at once. Specifically, that the correct bits are
+// written and byte boundaries are respected.
+TEST(TrieBitBufferTest, WriteBits) {
+  TrieBitBuffer buffer;
+
+  buffer.WriteBits(170, 1);
+  buffer.WriteBits(170, 2);
+  buffer.WriteBits(170, 3);
+
+  BitWriter writer;
+  buffer.WriteToBitWriter(&writer);
+  EXPECT_EQ(6U, writer.position());
+
+  writer.Flush();
+
+  // 0 + 10 + 010 + 00 (padding) = 0x48
+  EXPECT_THAT(writer.bytes(), testing::ElementsAre(0x48));
+
+  buffer.WriteBits(170, 2);
+  buffer.WriteBits(170, 2);
+
+  BitWriter writer2;
+  buffer.WriteToBitWriter(&writer2);
+  EXPECT_EQ(10U, writer2.position());
+
+  writer2.Flush();
+
+  // 0 + 10 + 010 + 10 + 10 + 000000 (padding) = 0x4A80.
+  EXPECT_THAT(writer2.bytes(), testing::ElementsAre(0x4A, 0x80));
+
+  buffer.WriteBits(170, 2);
+
+  BitWriter writer3;
+  buffer.WriteToBitWriter(&writer3);
+  EXPECT_EQ(12U, writer3.position());
+
+  writer3.Flush();
+
+  // 0 + 10 + 010 + 10 + 10 + 10 + 0000 (padding) = 0x4AA0.
+  EXPECT_THAT(writer3.bytes(), testing::ElementsAre(0x4A, 0xA0));
+}
+
+// Test writing position (delta's).
+TEST(TrieBitBufferTest, WritePosition) {
+  TrieBitBuffer buffer;
+  BitWriter writer;
+
+  buffer.WriteBit(1);
+  buffer.WriteBits(170, 6);
+
+  buffer.WriteToBitWriter(&writer);
+
+  TrieBitBuffer buffer2;
+  int32_t last_position = -1;
+  buffer2.WritePosition(4, &last_position);
+  EXPECT_EQ(4, last_position);
+
+  buffer2.WriteBits(170, 8);
+  buffer2.WritePosition(8, &last_position);
+  EXPECT_EQ(8, last_position);
+
+  buffer2.WriteToBitWriter(&writer);
+  writer.Flush();
+
+  EXPECT_EQ(4U, writer.bytes().size());
+
+  // The buffer should contain, in order:
+  // - the bit 1
+  // - the last 6 bits of '0xAA'
+  // - five bits representing '2'; the bit length of the following field
+  // - 2 bits representing '3' (the delta 7 - 4)
+  // - 8 bits representing 0xAA ('170')
+  // - A zero indicating the following 7 bits represent a delta
+  // - 7 bits representing 4 (the delta 8 - 4)
+  // - padding
+  //
+  // 1 + 101010 + 00010 + 11 + 10101010 + 0 + 0000100 + 00 (padding)
+  EXPECT_THAT(writer.bytes(), testing::ElementsAre(0xD4, 0x2E, 0xA8, 0x10));
+}
+
+// Test writing characters to the buffer using Huffman.
+TEST(TrieBitBufferTest, WriteChar) {
+  TrieBitBuffer buffer;
+  HuffmanBuilder huffman_builder;
+  HuffmanRepresentationTable table;
+
+  table['a'] = HuffmanRepresentation();
+  table['a'].bits = 0x0A;
+  table['a'].number_of_bits = 4;
+
+  table['b'] = HuffmanRepresentation();
+  table['b'].bits = 0x0F;
+  table['b'].number_of_bits = 4;
+
+  buffer.WriteChar('a', table, &huffman_builder);
+
+  HuffmanRepresentationTable encoding = huffman_builder.ToTable();
+
+  // 'a' should have a Huffman encoding.
+  EXPECT_NE(encoding.cend(), encoding.find('a'));
+
+  buffer.WriteChar('a', table, &huffman_builder);
+  buffer.WriteChar('b', table, &huffman_builder);
+
+  encoding = huffman_builder.ToTable();
+
+  // Both 'a' and 'b' should have a Huffman encoding.
+  EXPECT_NE(encoding.cend(), encoding.find('a'));
+  EXPECT_NE(encoding.cend(), encoding.find('b'));
+
+  BitWriter writer;
+  buffer.WriteToBitWriter(&writer);
+  writer.Flush();
+
+  // There should be 3 characters in the writer. 'a' twice followed by 'b' once.
+  // The characters are written as the representation in |table|.
+  EXPECT_EQ(2U, writer.bytes().size());
+
+  // Twice 'a', once 'b' and padding
+  EXPECT_THAT(writer.bytes(), testing::ElementsAre(0xAA, 0xF0));
+}
+
+// Test writing a mix of items. Specifically, that the correct values are
+// written in the correct order and byte boundaries are respected.
+TEST(TrieBitBufferTest, WriteMix) {
+  TrieBitBuffer buffer;
+
+  HuffmanRepresentationTable table;
+  table['a'] = HuffmanRepresentation();
+  table['a'].bits = 0x0A;
+  table['a'].number_of_bits = 4;
+
+  buffer.WriteBits(170, 1);
+  buffer.WriteBit(1);
+
+  buffer.WriteChar('a', table, nullptr);
+
+  buffer.WriteBits(170, 2);
+  buffer.WriteBits(170, 3);
+
+  BitWriter writer;
+  buffer.WriteToBitWriter(&writer);
+
+  // 1 + 1 + 4 + 2 + 3 = 11.
+  EXPECT_EQ(writer.position(), 11U);
+
+  TrieBitBuffer buffer2;
+  buffer2.WriteBit(1);
+  buffer2.WriteBits(170, 2);
+  buffer2.WriteBit(0);
+
+  buffer2.WriteToBitWriter(&writer);
+  EXPECT_EQ(writer.position(), 15U);
+  EXPECT_EQ(writer.bytes().size(), 1U);
+
+  writer.Flush();
+
+  EXPECT_EQ(writer.bytes().size(), 2U);
+
+  // 0 + 1 + 1010 + 10 + 010 + 1 + 10 + 0 + 0 (padding) = 0x6A58.
+  EXPECT_THAT(writer.bytes(), testing::ElementsAre(0x6A, 0x58));
+}
+
+}  // transport_security_state
+
+}  // namespace net