Adding a previews IO-thread blacklist

components/previews/previews_black_list_item_unittest.cc

+// 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/previews/previews_black_list_item.h"
+
+#include <memory>
+
+#include "base/time/time.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+
+using PreviewsBlackListItemTest = testing::Test;
+
+}  // namespace
+
+namespace previews {
+
+TEST_F(PreviewsBlackListItemTest, BlackListState) {
+  const int history = 4;
+  const int threshold = 2;
+  const base::TimeDelta duration = base::TimeDelta::FromSeconds(30);
+  const base::Time now = base::Time::UnixEpoch();
+  const base::TimeDelta delay_between_entries = base::TimeDelta::FromSeconds(1);
+  const base::Time later = now + duration + (delay_between_entries * 3);
+
+  std::unique_ptr<PreviewsBlackListItem> black_list_item(
+      new PreviewsBlackListItem(history, threshold, duration));
+
+  // Empty black list item should report that the host is allowed.
+  EXPECT_FALSE(black_list_item->IsBlackListed(now));
+  EXPECT_FALSE(black_list_item->IsBlackListed(later));
+
+  black_list_item->AddPreviewNavigation(true, now);
+  // Black list item of size less that |threshold| should report that the host
+  // is allowed.
+  EXPECT_FALSE(black_list_item->IsBlackListed(now));
+  EXPECT_FALSE(black_list_item->IsBlackListed(later));
+
+  black_list_item->AddPreviewNavigation(true, now + delay_between_entries);
+  // Black list item with |threshold| fresh entries should report the host as
+  // disallowed.
+  EXPECT_TRUE(black_list_item->IsBlackListed(now));
+  // Black list item with only entries from longer than |duration| ago should
+  // report the host is allowed.
+  EXPECT_FALSE(black_list_item->IsBlackListed(later));
+  black_list_item->AddPreviewNavigation(true,
+                                        later - (delay_between_entries * 2));
+  // Black list item with a fresh opt out and total number of opt outs larger
+  // than |threshold| should report the host is disallowed.
+  EXPECT_TRUE(black_list_item->IsBlackListed(later));
+
+  // The black list item should maintain entries based on time, so adding
+  // |history| entries should not push out newer entries.
+  black_list_item->AddPreviewNavigation(true,
+                                        later - delay_between_entries * 2);
+  black_list_item->AddPreviewNavigation(false,
+                                        later - delay_between_entries * 3);
+  black_list_item->AddPreviewNavigation(false,
+                                        later - delay_between_entries * 3);
+  black_list_item->AddPreviewNavigation(false,
+                                        later - delay_between_entries * 3);
+  black_list_item->AddPreviewNavigation(false,
+                                        later - delay_between_entries * 3);
+  EXPECT_TRUE(black_list_item->IsBlackListed(later));
+
+  // The black list item should maintain entries based on time, so adding
+  // |history| newer entries should push out older entries.
+  black_list_item->AddPreviewNavigation(false,
+                                        later - delay_between_entries * 1);
+  black_list_item->AddPreviewNavigation(false,
+                                        later - delay_between_entries * 1);
+  black_list_item->AddPreviewNavigation(false,
+                                        later - delay_between_entries * 1);
+  black_list_item->AddPreviewNavigation(false,
+                                        later - delay_between_entries * 1);
+  EXPECT_FALSE(black_list_item->IsBlackListed(later));
+}
+
+}  // namespace previews