Add the request picker and a unit test

components/offline_pages/background/request_picker_unittest.cc

Index: components/offline_pages/background/request_picker_unittest.cc
diff --git a/components/offline_pages/background/request_picker_unittest.cc b/components/offline_pages/background/request_picker_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..3f4b029611c1da75821bf9d7ceb1749dcdee24e9
--- /dev/null
+++ b/components/offline_pages/background/request_picker_unittest.cc
@@ -0,0 +1,127 @@
+// Copyright 2016 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 "components/offline_pages/background/request_picker.h"
+
+#include "base/bind.h"
+#include "base/test/test_simple_task_runner.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "base/time/time.h"
+#include "components/offline_pages/background/request_queue.h"
+#include "components/offline_pages/background/request_queue_in_memory_store.h"
+#include "components/offline_pages/background/save_page_request.h"
+#include "components/offline_pages/offline_page_item.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace offline_pages {
+
+namespace {
+// Data for request 1.
+const int64_t kRequestId1 = 17;
+const GURL kUrl1("https://google.com");
+const ClientId kClientId1("bookmark", "1234");
+// Data for request 2.
+const int64_t kRequestId2 = 42;
+const GURL kUrl2("http://nytimes.com");
+const ClientId kClientId2("bookmark", "5678");
+}  // namespace
+
+class RequestPickerTest : public testing::Test {
+ public:
+  RequestPickerTest();
+
+  ~RequestPickerTest() override;
+
+  void SetUp() override;
+
+  void PumpLoop();
+
+  void AddRequestDone(RequestQueue::AddRequestResult result,
+                      const SavePageRequest& request);
+
+  void RequestPicked(const SavePageRequest& request);
+
+  void RequestQueueEmpty();
+
+ protected:
+  // The request queue is simple enough we will use a real queue, not a stub.

[dougarnett, 2016/05/31 18:03:04]

... use a real queue with memory store.    ?

+  std::unique_ptr<RequestQueue> queue_;
+  std::unique_ptr<RequestPicker> picker_;
+  std::unique_ptr<SavePageRequest> last_picked_;
+  bool request_queue_empty_called_;
+
+ private:
+  scoped_refptr<base::TestSimpleTaskRunner> task_runner_;
+  base::ThreadTaskRunnerHandle task_runner_handle_;
+};
+
+RequestPickerTest::RequestPickerTest()
+    : task_runner_(new base::TestSimpleTaskRunner),
+      task_runner_handle_(task_runner_) {}
+
+RequestPickerTest::~RequestPickerTest() {}
+
+void RequestPickerTest::SetUp() {
+  std::unique_ptr<RequestQueueInMemoryStore> store(
+      new RequestQueueInMemoryStore());
+  queue_.reset(new RequestQueue(std::move(store)));
+  picker_.reset(new RequestPicker(
+      queue_.get(),
+      base::Bind(&RequestPickerTest::RequestPicked, base::Unretained(this)),
+      base::Bind(&RequestPickerTest::RequestQueueEmpty,
+                 base::Unretained(this))));
+  request_queue_empty_called_ = false;
+}
+
+void RequestPickerTest::PumpLoop() {
+  task_runner_->RunUntilIdle();
+}
+
+void RequestPickerTest::AddRequestDone(RequestQueue::AddRequestResult result,
+                                       const SavePageRequest& request) {}
+
+void RequestPickerTest::RequestPicked(const SavePageRequest& request) {
+  last_picked_.reset(new SavePageRequest(request));
+}
+
+void RequestPickerTest::RequestQueueEmpty() {
+  request_queue_empty_called_ = true;
+}
+
+TEST_F(RequestPickerTest, ChooseNextRequest) {
+  base::Time creation_time = base::Time::Now();
+  SavePageRequest request1(kRequestId1, kUrl1, kClientId1, creation_time);
+  SavePageRequest request2(kRequestId2, kUrl2, kClientId2, creation_time);
+  // Put some test requests on the Queue.
+  queue_->AddRequest(request1, base::Bind(&RequestPickerTest::AddRequestDone,
+                                          base::Unretained(this)));
+  queue_->AddRequest(request2, base::Bind(&RequestPickerTest::AddRequestDone,
+                                          base::Unretained(this)));
+
+  // Pump the loop to give the async queue the opportunity to do the adds.
+  PumpLoop();
+
+  picker_->ChooseNextRequest();
+
+  // Pump the loop again to give the async queue the opportunity to return
+  // results from the Get operation, and for the picker to call the "picked"
+  // callback.
+  PumpLoop();
+
+  EXPECT_EQ(kRequestId1, last_picked_->request_id());
+  EXPECT_FALSE(request_queue_empty_called_);
+}
+
+TEST_F(RequestPickerTest, PickFromEmptyQueue) {
+  picker_->ChooseNextRequest();
+
+  // Pump the loop again to give the async queue the opportunity to return
+  // results from the Get operation, and for the picker to call the "QueueEmpty"
+  // callback.
+  PumpLoop();
+
+  EXPECT_TRUE(request_queue_empty_called_);
+}
+
+}  // namespace offline_pages