src/chrome/common/metrics/caching_permuted_entropy_provider_unittest.cc

   1 // Copyright 2013 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "chrome/common/metrics/caching_permuted_entropy_provider.h"
   6
   7 #include <string>
   8
   9 #include "base/basictypes.h"
  10 #include "base/prefs/testing_pref_service.h"
  11 #include "testing/gtest/include/gtest/gtest.h"
  12
  13 namespace metrics {
  14
  15 // Size of the low entropy source to use for the permuted entropy provider
  16 // in tests.
  17 const size_t kMaxLowEntropySize = 8000;
  18
  19 // Field trial names used in unit tests.
  20 const char* const kTestTrialNames[] = { "TestTrial", "AnotherTestTrial",
  21                                         "NewTabButton" };
  22
  23 TEST(CachingPermutedEntropyProviderTest, HasConsistentResults) {
  24   TestingPrefServiceSimple prefs;
  25   CachingPermutedEntropyProvider::RegisterPrefs(prefs.registry());
  26   const int kEntropyValue = 1234;
  27
  28   // Check that the caching provider returns the same results as the non caching
  29   // one. Loop over the trial names twice, to test that caching returns the
  30   // expected results.
  31   PermutedEntropyProvider provider(kEntropyValue, kMaxLowEntropySize);
  32   for (size_t i = 0; i < 2 * arraysize(kTestTrialNames); ++i) {
  33     CachingPermutedEntropyProvider cached_provider(&prefs, kEntropyValue,
  34                                                    kMaxLowEntropySize);
  35     const std::string trial_name =
  36         kTestTrialNames[i % arraysize(kTestTrialNames)];
  37     EXPECT_DOUBLE_EQ(provider.GetEntropyForTrial(trial_name, 0),
  38                      cached_provider.GetEntropyForTrial(trial_name, 0));
  39   }
  40
  41   // Now, do the same test re-using the same caching provider.
  42   CachingPermutedEntropyProvider cached_provider(&prefs, kEntropyValue,
  43                                                  kMaxLowEntropySize);
  44   for (size_t i = 0; i < 2 * arraysize(kTestTrialNames); ++i) {
  45     const std::string trial_name =
  46         kTestTrialNames[i % arraysize(kTestTrialNames)];
  47     EXPECT_DOUBLE_EQ(provider.GetEntropyForTrial(trial_name, 0),
  48                      cached_provider.GetEntropyForTrial(trial_name, 0));
  49   }
  50 }
  51
  52 }  // namespace metrics