Add unittests for different transport security state generator components.

net/tools/transport_security_state_generator/bit_writer_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/bit_writer.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace net {
+
+namespace transport_security_state {
+
+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 transport_security_state
+
+}  // namespace net