Adding partially circular memory buffer wrapper.

content/common/partial_circular_buffer_unittest.cc

Index: content/common/partial_circular_buffer_unittest.cc
diff --git a/content/common/partial_circular_buffer_unittest.cc b/content/common/partial_circular_buffer_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..5925667da3e413847d2618b8eda45512e785bdba
--- /dev/null
+++ b/content/common/partial_circular_buffer_unittest.cc
@@ -0,0 +1,138 @@
+// Copyright (c) 2013 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.
+
+// The test buffer data is 52 bytes, wrap position is set to 20 (this is
+// arbitrarily chosen). The total buffer size is allocated dynamically based on
+// the actual header size. This gives:
+// Header of some size, non-wrapping part 20 bytes, wrapping part 32 bytes.
+// As input data, a 14 byte array is used and repeatedly written. It's chosen
+// not to be an integer factor smaller than the wrapping part. This ensures that
+// the wrapped data isn't repeated at the same position.
+// Note that desipte the number of wraps (if one or more), the reference output
+// data is the same since the offset at each wrap is always the same.
+
+#include "base/memory/scoped_ptr.h"
+#include "content/common/partial_circular_buffer.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace content {
+
+const uint32 kWrapPosition = 20;
+const uint8 kInputData[] = {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14};
+const uint8 kOutputRefDataWrap[] =
+    // The 20 bytes in the non-wrapping part.
+    {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 1, 2, 3, 4, 5, 6,
+     // The 32 bytes in wrapping part.
+     11, 12, 13, 14,
+     1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
+     1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14};
+
+class PartialCircularBufferTest : public testing::Test {
+ public:
+  PartialCircularBufferTest() {
+    PartialCircularBuffer::BufferData test_struct;
+    buffer_header_size_ =
+        &test_struct.data[0] - reinterpret_cast<uint8*>(&test_struct);
+
+    buffer_.reset(new uint8[buffer_header_size_ + sizeof(kOutputRefDataWrap)]);
+    pcb_write_.reset(new PartialCircularBuffer(
+        buffer_.get(),
+        buffer_header_size_ + sizeof(kOutputRefDataWrap),
+        kWrapPosition));
+  }
+
+  void WriteToBuffer(int num) {
+    for (int i = 0; i < num; ++i)
+      pcb_write_->Write(kInputData, sizeof(kInputData));
+  }
+
+  void InitReadBuffer() {
+    pcb_read_.reset(new PartialCircularBuffer(
+        buffer_.get(), buffer_header_size_ + sizeof(kOutputRefDataWrap)));
+  }
+
+ protected:
+  scoped_ptr<PartialCircularBuffer> pcb_write_;
+  scoped_ptr<PartialCircularBuffer> pcb_read_;
+  scoped_ptr<uint8[]> buffer_;
+  uint32 buffer_header_size_;
+
+  DISALLOW_COPY_AND_ASSIGN(PartialCircularBufferTest);
+};
+
+TEST_F(PartialCircularBufferTest, NoWrapBeginningPartOnly) {
+  WriteToBuffer(1);
+  InitReadBuffer();
+
+  uint8 output_data[sizeof(kInputData)] = {0};
+  EXPECT_EQ(sizeof(output_data),
+            pcb_read_->Read(output_data, sizeof(output_data)));
+
+  EXPECT_EQ(0, memcmp(kInputData, output_data, sizeof(kInputData)));
+
+  EXPECT_EQ(0u, pcb_read_->Read(output_data, sizeof(output_data)));
+}
+
+TEST_F(PartialCircularBufferTest, NoWrapBeginningAndEndParts) {
+  WriteToBuffer(2);
+  InitReadBuffer();
+
+  uint8 output_data[2 * sizeof(kInputData)] = {0};
+  EXPECT_EQ(sizeof(output_data),
+            pcb_read_->Read(output_data, sizeof(output_data)));
+
+  const uint8 output_ref_data[2 * sizeof(kInputData)] =
+      {1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14,
+       1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14};
+  EXPECT_EQ(0, memcmp(output_ref_data, output_data, sizeof(output_data)));
+
+  EXPECT_EQ(0u, pcb_read_->Read(output_data, sizeof(output_data)));
+}
+
+TEST_F(PartialCircularBufferTest, WrapOnce) {
+  WriteToBuffer(4);
+  InitReadBuffer();
+
+  uint8 output_data[sizeof(kOutputRefDataWrap)] = {0};
+  EXPECT_EQ(sizeof(output_data),
+            pcb_read_->Read(output_data, sizeof(output_data)));
+
+  EXPECT_EQ(0, memcmp(kOutputRefDataWrap, output_data, sizeof(output_data)));
+
+  EXPECT_EQ(0u, pcb_read_->Read(output_data, sizeof(output_data)));
+}
+
+TEST_F(PartialCircularBufferTest, WrapTwice) {
+  WriteToBuffer(7);
+  InitReadBuffer();
+
+  uint8 output_data[sizeof(kOutputRefDataWrap)] = {0};
+  EXPECT_EQ(sizeof(output_data),
+            pcb_read_->Read(output_data, sizeof(output_data)));
+
+  EXPECT_EQ(0, memcmp(kOutputRefDataWrap, output_data, sizeof(output_data)));
+
+  EXPECT_EQ(0u, pcb_read_->Read(output_data, sizeof(output_data)));
+}
+
+TEST_F(PartialCircularBufferTest, WrapOnceSmallerOutputBuffer) {
+  WriteToBuffer(4);
+  InitReadBuffer();
+
+  uint8 output_data[sizeof(kOutputRefDataWrap)] = {0};
+  const uint32 size_per_read = 16;
+  uint32 read = 0;
+  for (; read + size_per_read <= sizeof(output_data); read += size_per_read) {
+    EXPECT_EQ(size_per_read,
+              pcb_read_->Read(output_data + read, size_per_read));
+  }
+  EXPECT_EQ(sizeof(output_data) - read,
+            pcb_read_->Read(output_data + read, size_per_read));
+
+  EXPECT_EQ(0, memcmp(kOutputRefDataWrap, output_data, sizeof(output_data)));
+
+  EXPECT_EQ(0u, pcb_read_->Read(output_data, sizeof(output_data)));
+}
+
+}  // namespace content