[Offline Pages] Set up the initial prefetching service.

chrome/browser/android/offline_pages/offline_page_suggestions_observer_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 "chrome/browser/android/offline_pages/offline_page_suggestions_observer.h"
+
+#include "base/run_loop.h"
+#include "base/test/test_simple_task_runner.h"
+#include "base/threading/thread_task_runner_handle.h"
+#include "chrome/test/base/testing_profile.h"
+#include "components/offline_pages/core/stub_offline_page_model.h"
+#include "content/public/test/test_browser_thread_bundle.h"
+#include "testing/gtest/include/gtest/gtest.h"
+#include "url/gurl.h"
+
+namespace offline_pages {
+
+namespace {
+class TestDelegate : public OfflinePageSuggestionsObserver::Delegate {
+ public:
+  TestDelegate() = default;
+  ~TestDelegate() override = default;
+
+  std::vector<GURL> GetSuggestionURLs() override {
+    get_suggestion_urls_count++;
+    return suggestion_urls;
+  }
+
+  void GetPagesWithURLs(
+      const std::vector<GURL>& suggestion_urls,
+      const MultipleOfflinePageItemCallback& callback) override {
+    get_pages_with_urls_count++;
+    callback.Run(matching_pages);
+  }
+
+  // Public for test manipulation.
+  std::vector<GURL> suggestion_urls;
+  std::vector<OfflinePageItem> matching_pages;
+
+  // Signals that delegate was called.
+  int get_suggestion_urls_count = 0;
+  int get_pages_with_urls_count = 0;
+};
+
+}  // namespace
+
+class OfflinePageSuggestionsObserverTest : public testing::Test {
+ public:
+  OfflinePageSuggestionsObserverTest() = default;
+
+  void SetUp() override {
+    observer_ = base::MakeUnique<OfflinePageSuggestionsObserver>(
+        &profile_, MakeDelegate(), category);
+  }
+
+  virtual std::unique_ptr<OfflinePageSuggestionsObserver::Delegate>
+  MakeDelegate() {
+    auto delegate_ptr = base::MakeUnique<TestDelegate>();
+    test_delegate_ = delegate_ptr.get();
+    return std::move(delegate_ptr);
+  }
+
+  OfflinePageSuggestionsObserver* observer() { return observer_.get(); }
+
+  TestDelegate* test_delegate() { return test_delegate_; }
+
+ protected:
+  ntp_snippets::Category category = ntp_snippets::Category::FromKnownCategory(
+      ntp_snippets::KnownCategories::ARTICLES);
+  content::TestBrowserThreadBundle thread_bundle_;
+  TestingProfile profile_;
+
+ private:
+  std::unique_ptr<OfflinePageSuggestionsObserver> observer_;
+  TestDelegate* test_delegate_;
+};
+
+TEST_F(OfflinePageSuggestionsObserverTest, CallsDelegateOnNewSuggestions) {
+  // We should not do anything if the category is not loaded.
+  observer()->OnNewSuggestions(category);
+  EXPECT_EQ(0, test_delegate()->get_suggestion_urls_count);
+  EXPECT_EQ(0, test_delegate()->get_pages_with_urls_count);
+
+  // Once the category becomes available, new suggestions should cause us to ask
+  // the delegate for suggestion URLs.
+  observer()->OnCategoryStatusChanged(category,
+                                      ntp_snippets::CategoryStatus::AVAILABLE);
+  observer()->OnNewSuggestions(category);
+  EXPECT_EQ(1, test_delegate()->get_suggestion_urls_count);
+  EXPECT_EQ(1, test_delegate()->get_pages_with_urls_count);
+}
+
+}  // namespace offline_pages