Introduce ParallelDownloadJob.

content/browser/download/parallel_download_job_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 "content/browser/download/parallel_download_job.h"
+
+#include <utility>
+#include <vector>
+
+#include "base/memory/ptr_util.h"
+#include "content/browser/download/download_item_impl_delegate.h"
+#include "content/browser/download/mock_download_item_impl.h"
+#include "content/public/test/test_browser_thread_bundle.h"
+#include "testing/gmock/include/gmock/gmock.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+using ::testing::NiceMock;
+
+namespace content {
+
+namespace {
+
+class MockDownloadRequestHandle : public DownloadRequestHandleInterface {
+ public:
+  MOCK_CONST_METHOD0(GetWebContents, WebContents*());
+  MOCK_CONST_METHOD0(GetDownloadManager, DownloadManager*());
+  MOCK_CONST_METHOD0(PauseRequest, void());
+  MOCK_CONST_METHOD0(ResumeRequest, void());
+  MOCK_CONST_METHOD0(CancelRequest, void());
+  MOCK_CONST_METHOD0(DebugString, std::string());
+};
+
+}  // namespace
+
+class ParallelDownloadJobForTest : public ParallelDownloadJob {
+ public:
+  ParallelDownloadJobForTest(
+      DownloadItemImpl* download_item,
+      std::unique_ptr<DownloadRequestHandleInterface> request_handle)
+      : ParallelDownloadJob(download_item, std::move(request_handle)) {}
+
+  void CreateRequest(int64_t offset, int64_t length) override {
+    fake_tasks_.push_back(std::pair<int64_t, int64_t>(offset, length));
+  }
+
+  std::vector<std::pair<int64_t, int64_t>> fake_tasks_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(ParallelDownloadJobForTest);
+};
+
+class ParallelDownloadJobTest : public testing::Test {
+ public:
+  void SetUp() override {
+    item_delegate_ = base::MakeUnique<DownloadItemImplDelegate>();
+    download_item_ =
+        base::MakeUnique<NiceMock<MockDownloadItemImpl>>(item_delegate_.get());
+    job_ = base::MakeUnique<ParallelDownloadJobForTest>(
+        download_item_.get(), base::MakeUnique<MockDownloadRequestHandle>());
+  }
+
+  void CreateNewDownloadRequests(int64_t total_bytes,
+                                 int64_t bytes_received,
+                                 int request_num) {
+    job_->request_num_ = request_num;
+    job_->ForkRequestsForNewDownload(bytes_received, total_bytes);
+  }
+
+  content::TestBrowserThreadBundle browser_threads_;
+  std::unique_ptr<DownloadItemImplDelegate> item_delegate_;
+  std::unique_ptr<MockDownloadItemImpl> download_item_;
+  std::unique_ptr<ParallelDownloadJobForTest> job_;
+};
+
+// Test if sub tasks are created correctly.
+TEST_F(ParallelDownloadJobTest, CreateNewDownloadRequests) {
+  EXPECT_TRUE(job_->fake_tasks_.empty());
+
+  // Totally 2 requests for 100 bytes.
+  // Original request:  Range:0-49, for 50 bytes.
+  // Task 1:  Range:50-99, for 50 bytes.
+  CreateNewDownloadRequests(100, 0, 2);
+  EXPECT_EQ(1, static_cast<int>(job_->fake_tasks_.size()));
+  EXPECT_EQ(50, job_->fake_tasks_[0].first);
+  EXPECT_EQ(50, job_->fake_tasks_[0].second);
+  job_->fake_tasks_.clear();
+
+  // Totally 3 requests for 100 bytes.
+  // Original request:  Range:0-32, for 33 bytes.
+  // Task 1:  Range:33-65, for 33 bytes.
+  // Task 2:  Range:66-99, for 34 bytes.
+  CreateNewDownloadRequests(100, 0, 3);
+  EXPECT_EQ(2, static_cast<int>(job_->fake_tasks_.size()));
+  EXPECT_EQ(33, job_->fake_tasks_[0].first);
+  EXPECT_EQ(33, job_->fake_tasks_[0].second);
+  EXPECT_EQ(66, job_->fake_tasks_[1].first);
+  EXPECT_EQ(34, job_->fake_tasks_[1].second);
+  job_->fake_tasks_.clear();
+
+  // Totally 3 requests for 100 bytes. Start from the 17th byte.
+  // Original request:  Range:17-43, for 27 bytes.
+  // Task 1:  Range:44-70, for 27 bytes.
+  // Task 2:  Range:71-99, for 29 bytes.
+  CreateNewDownloadRequests(100, 17, 3);
+  EXPECT_EQ(2, static_cast<int>(job_->fake_tasks_.size()));
+  EXPECT_EQ(44, job_->fake_tasks_[0].first);
+  EXPECT_EQ(27, job_->fake_tasks_[0].second);
+  EXPECT_EQ(71, job_->fake_tasks_[1].first);
+  EXPECT_EQ(29, job_->fake_tasks_[1].second);
+  job_->fake_tasks_.clear();
+
+  // Less than 2 requests, do nothing.
+  CreateNewDownloadRequests(100, 17, 1);
+  EXPECT_TRUE(job_->fake_tasks_.empty());
+  CreateNewDownloadRequests(100, 17, 0);
+  EXPECT_TRUE(job_->fake_tasks_.empty());
+
+  // Received bytes are no less than total bytes, do nothing.
+  CreateNewDownloadRequests(100, 100, 3);
+  EXPECT_TRUE(job_->fake_tasks_.empty());
+  CreateNewDownloadRequests(100, 255, 3);
+  EXPECT_TRUE(job_->fake_tasks_.empty());
+
+  // Edge cases for 0 bytes.
+  CreateNewDownloadRequests(0, 0, 3);
+  EXPECT_TRUE(job_->fake_tasks_.empty());
+
+  // 2 bytes left for 3 additional requests. Only 1 are built.
+  // Original request:  Range:98-98, for 1 byte.
+  // Task 1:  Range:99-99, for 1 byte.
+  CreateNewDownloadRequests(100, 98, 4);
+  EXPECT_EQ(1, static_cast<int>(job_->fake_tasks_.size()));
+  EXPECT_EQ(99, job_->fake_tasks_[0].first);
+  EXPECT_EQ(1, job_->fake_tasks_[0].second);
+  job_->fake_tasks_.clear();
+}
+
+}  // namespace content