Introduce a request throttler for limiting requests in mobile NTP.

components/ntp_snippets/request_counter_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/ntp_snippets/request_counter.h"
+
+#include <memory>
+
+#include "base/strings/stringprintf.h"
+#include "components/ntp_snippets/pref_names.h"
+#include "components/prefs/pref_registry_simple.h"
+#include "components/prefs/testing_pref_service.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace {
+const int kCounterQuota = 2;
+}  // namespace
+
+namespace ntp_snippets {
+
+class RequestCounterTest : public testing::Test {
+ public:
+  RequestCounterTest() {
+    RequestCounter::RegisterProfilePrefs(test_prefs_.registry());
+    // Use any arbitrary RequestType for this unittest.
+    counter_.reset(new RequestCounter(
+        &test_prefs_, RequestCounter::RequestType::ARTICLE_CONTENT_FETCHER,
+        kCounterQuota));
+  }
+
+ protected:
+  TestingPrefServiceSimple test_prefs_;
+  std::unique_ptr<RequestCounter> counter_;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(RequestCounterTest);
+};
+
+TEST_F(RequestCounterTest, QuotaExceeded) {
+  EXPECT_TRUE(counter_->DemandQuotaForRequest());
+  EXPECT_TRUE(counter_->DemandQuotaForRequest());
+  EXPECT_FALSE(counter_->DemandQuotaForRequest());
+}
+
+TEST_F(RequestCounterTest, ForcedDoesNotCountInQuota) {
+  EXPECT_TRUE(counter_->DemandQuotaForRequest());
+  counter_->ReportForcedRequest();
+  EXPECT_TRUE(counter_->DemandQuotaForRequest());
+}
+
+TEST_F(RequestCounterTest, QuotaIsPerDay) {
+  EXPECT_TRUE(counter_->DemandQuotaForRequest());
+  EXPECT_TRUE(counter_->DemandQuotaForRequest());
+
+  // Now fake the day pref so that the counter believes the count comes from
+  // yesterday.
+  int now_day = (base::Time::Now() - base::Time::UnixEpoch()).InDays();
+  test_prefs_.SetInteger(ntp_snippets::prefs::kSnippetFetcherQuotaDay,
+                         now_day - 1);
+
+  // The quota should get reset as the day has changed.
+  EXPECT_TRUE(counter_->DemandQuotaForRequest());
+}
+
+}  // namespace ntp_snippets