base/metrics/field_trial_unittest.cc

   1 // Copyright (c) 2012 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 "base/metrics/field_trial.h"
   6
   7 #include "base/build_time.h"
   8 #include "base/message_loop/message_loop.h"
   9 #include "base/rand_util.h"
  10 #include "base/run_loop.h"
  11 #include "base/strings/string_number_conversions.h"
  12 #include "base/strings/stringprintf.h"
  13 #include "testing/gtest/include/gtest/gtest.h"
  14
  15 namespace base {
  16
  17 namespace {
  18
  19 // Default group name used by several tests.
  20 const char kDefaultGroupName[] = "DefaultGroup";
  21
  22 // Call FieldTrialList::FactoryGetFieldTrial() with a future expiry date.
  23 scoped_refptr<base::FieldTrial> CreateFieldTrial(
  24     const std::string& trial_name,
  25     int total_probability,
  26     const std::string& default_group_name,
  27     int* default_group_number) {
  28   return FieldTrialList::FactoryGetFieldTrial(
  29       trial_name, total_probability, default_group_name,
  30       base::FieldTrialList::kNoExpirationYear, 1, 1,
  31       base::FieldTrial::SESSION_RANDOMIZED, default_group_number);
  32 }
  33
  34 int OneYearBeforeBuildTime() {
  35   Time one_year_before_build_time = GetBuildTime() - TimeDelta::FromDays(365);
  36   Time::Exploded exploded;
  37   one_year_before_build_time.LocalExplode(&exploded);
  38   return exploded.year;
  39 }
  40
  41 // FieldTrialList::Observer implementation for testing.
  42 class TestFieldTrialObserver : public FieldTrialList::Observer {
  43  public:
  44   TestFieldTrialObserver() {
  45     FieldTrialList::AddObserver(this);
  46   }
  47
  48   ~TestFieldTrialObserver() override { FieldTrialList::RemoveObserver(this); }
  49
  50   void OnFieldTrialGroupFinalized(const std::string& trial,
  51                                   const std::string& group) override {
  52     trial_name_ = trial;
  53     group_name_ = group;
  54   }
  55
  56   const std::string& trial_name() const { return trial_name_; }
  57   const std::string& group_name() const { return group_name_; }
  58
  59  private:
  60   std::string trial_name_;
  61   std::string group_name_;
  62
  63   DISALLOW_COPY_AND_ASSIGN(TestFieldTrialObserver);
  64 };
  65
  66 }  // namespace
  67
  68 class FieldTrialTest : public testing::Test {
  69  public:
  70   FieldTrialTest() : trial_list_(NULL) {}
  71
  72  private:
  73   MessageLoop message_loop_;
  74   FieldTrialList trial_list_;
  75 };
  76
  77 // Test registration, and also check that destructors are called for trials
  78 // (and that Valgrind doesn't catch us leaking).
  79 TEST_F(FieldTrialTest, Registration) {
  80   const char name1[] = "name 1 test";
  81   const char name2[] = "name 2 test";
  82   EXPECT_FALSE(FieldTrialList::Find(name1));
  83   EXPECT_FALSE(FieldTrialList::Find(name2));
  84
  85   scoped_refptr<FieldTrial> trial1 =
  86       CreateFieldTrial(name1, 10, "default name 1 test", NULL);
  87   EXPECT_EQ(FieldTrial::kNotFinalized, trial1->group_);
  88   EXPECT_EQ(name1, trial1->trial_name());
  89   EXPECT_EQ("", trial1->group_name_internal());
  90
  91   trial1->AppendGroup(std::string(), 7);
  92
  93   EXPECT_EQ(trial1.get(), FieldTrialList::Find(name1));
  94   EXPECT_FALSE(FieldTrialList::Find(name2));
  95
  96   scoped_refptr<FieldTrial> trial2 =
  97       CreateFieldTrial(name2, 10, "default name 2 test", NULL);
  98   EXPECT_EQ(FieldTrial::kNotFinalized, trial2->group_);
  99   EXPECT_EQ(name2, trial2->trial_name());
 100   EXPECT_EQ("", trial2->group_name_internal());
 101
 102   trial2->AppendGroup("a first group", 7);
 103
 104   EXPECT_EQ(trial1.get(), FieldTrialList::Find(name1));
 105   EXPECT_EQ(trial2.get(), FieldTrialList::Find(name2));
 106   // Note: FieldTrialList should delete the objects at shutdown.
 107 }
 108
 109 TEST_F(FieldTrialTest, AbsoluteProbabilities) {
 110   char always_true[] = " always true";
 111   char default_always_true[] = " default always true";
 112   char always_false[] = " always false";
 113   char default_always_false[] = " default always false";
 114   for (int i = 1; i < 250; ++i) {
 115     // Try lots of names, by changing the first character of the name.
 116     char c = static_cast<char>(i);
 117     always_true[0] = c;
 118     default_always_true[0] = c;
 119     always_false[0] = c;
 120     default_always_false[0] = c;
 121
 122     scoped_refptr<FieldTrial> trial_true =
 123         CreateFieldTrial(always_true, 10, default_always_true, NULL);
 124     const std::string winner = "TheWinner";
 125     int winner_group = trial_true->AppendGroup(winner, 10);
 126
 127     EXPECT_EQ(winner_group, trial_true->group());
 128     EXPECT_EQ(winner, trial_true->group_name());
 129
 130     scoped_refptr<FieldTrial> trial_false =
 131         CreateFieldTrial(always_false, 10, default_always_false, NULL);
 132     int loser_group = trial_false->AppendGroup("ALoser", 0);
 133
 134     EXPECT_NE(loser_group, trial_false->group());
 135   }
 136 }
 137
 138 TEST_F(FieldTrialTest, RemainingProbability) {
 139   // First create a test that hasn't had a winner yet.
 140   const std::string winner = "Winner";
 141   const std::string loser = "Loser";
 142   scoped_refptr<FieldTrial> trial;
 143   int counter = 0;
 144   int default_group_number = -1;
 145   do {
 146     std::string name = StringPrintf("trial%d", ++counter);
 147     trial = CreateFieldTrial(name, 10, winner, &default_group_number);
 148     trial->AppendGroup(loser, 5);  // 50% chance of not being chosen.
 149     // If a group is not assigned, group_ will be kNotFinalized.
 150   } while (trial->group_ != FieldTrial::kNotFinalized);
 151
 152   // And that 'default' group (winner) should always win.
 153   EXPECT_EQ(default_group_number, trial->group());
 154
 155   // And that winner should ALWAYS win.
 156   EXPECT_EQ(winner, trial->group_name());
 157 }
 158
 159 TEST_F(FieldTrialTest, FiftyFiftyProbability) {
 160   // Check that even with small divisors, we have the proper probabilities, and
 161   // all outcomes are possible.  Since this is a 50-50 test, it should get both
 162   // outcomes in a few tries, but we'll try no more than 100 times (and be flaky
 163   // with probability around 1 in 2^99).
 164   bool first_winner = false;
 165   bool second_winner = false;
 166   int counter = 0;
 167   do {
 168     std::string name = base::StringPrintf("FiftyFifty%d", ++counter);
 169     std::string default_group_name = base::StringPrintf("Default FiftyFifty%d",
 170                                                         ++counter);
 171     scoped_refptr<FieldTrial> trial =
 172         CreateFieldTrial(name, 2, default_group_name, NULL);
 173     trial->AppendGroup("first", 1);  // 50% chance of being chosen.
 174     // If group_ is kNotFinalized, then a group assignement hasn't been done.
 175     if (trial->group_ != FieldTrial::kNotFinalized) {
 176       first_winner = true;
 177       continue;
 178     }
 179     trial->AppendGroup("second", 1);  // Always chosen at this point.
 180     EXPECT_NE(FieldTrial::kNotFinalized, trial->group());
 181     second_winner = true;
 182   } while ((!second_winner || !first_winner) && counter < 100);
 183   EXPECT_TRUE(second_winner);
 184   EXPECT_TRUE(first_winner);
 185 }
 186
 187 TEST_F(FieldTrialTest, MiddleProbabilities) {
 188   char name[] = " same name";
 189   char default_group_name[] = " default same name";
 190   bool false_event_seen = false;
 191   bool true_event_seen = false;
 192   for (int i = 1; i < 250; ++i) {
 193     char c = static_cast<char>(i);
 194     name[0] = c;
 195     default_group_name[0] = c;
 196     scoped_refptr<FieldTrial> trial =
 197         CreateFieldTrial(name, 10, default_group_name, NULL);
 198     int might_win = trial->AppendGroup("MightWin", 5);
 199
 200     if (trial->group() == might_win) {
 201       true_event_seen = true;
 202     } else {
 203       false_event_seen = true;
 204     }
 205     if (false_event_seen && true_event_seen)
 206       return;  // Successful test!!!
 207   }
 208   // Very surprising to get here. Probability should be around 1 in 2 ** 250.
 209   // One of the following will fail.
 210   EXPECT_TRUE(false_event_seen);
 211   EXPECT_TRUE(true_event_seen);
 212 }
 213
 214 TEST_F(FieldTrialTest, OneWinner) {
 215   char name[] = "Some name";
 216   char default_group_name[] = "Default some name";
 217   int group_count(10);
 218
 219   int default_group_number = -1;
 220   scoped_refptr<FieldTrial> trial =
 221       CreateFieldTrial(name, group_count, default_group_name, NULL);
 222   int winner_index(-2);
 223   std::string winner_name;
 224
 225   for (int i = 1; i <= group_count; ++i) {
 226     int might_win = trial->AppendGroup(std::string(), 1);
 227
 228     // Because we keep appending groups, we want to see if the last group that
 229     // was added has been assigned or not.
 230     if (trial->group_ == might_win) {
 231       EXPECT_EQ(-2, winner_index);
 232       winner_index = might_win;
 233       StringAppendF(&winner_name, "%d", might_win);
 234       EXPECT_EQ(winner_name, trial->group_name());
 235     }
 236   }
 237   EXPECT_GE(winner_index, 0);
 238   // Since all groups cover the total probability, we should not have
 239   // chosen the default group.
 240   EXPECT_NE(trial->group(), default_group_number);
 241   EXPECT_EQ(trial->group(), winner_index);
 242   EXPECT_EQ(trial->group_name(), winner_name);
 243 }
 244
 245 TEST_F(FieldTrialTest, DisableProbability) {
 246   const std::string default_group_name = "Default group";
 247   const std::string loser = "Loser";
 248   const std::string name = "Trial";
 249
 250   // Create a field trail that has expired.
 251   int default_group_number = -1;
 252   FieldTrial* trial = FieldTrialList::FactoryGetFieldTrial(
 253       name, 1000000000, default_group_name, OneYearBeforeBuildTime(), 1, 1,
 254       FieldTrial::SESSION_RANDOMIZED,
 255       &default_group_number);
 256   trial->AppendGroup(loser, 999999999);  // 99.9999999% chance of being chosen.
 257
 258   // Because trial has expired, we should always be in the default group.
 259   EXPECT_EQ(default_group_number, trial->group());
 260
 261   // And that default_group_name should ALWAYS win.
 262   EXPECT_EQ(default_group_name, trial->group_name());
 263 }
 264
 265 TEST_F(FieldTrialTest, ActiveGroups) {
 266   std::string no_group("No Group");
 267   scoped_refptr<FieldTrial> trial =
 268       CreateFieldTrial(no_group, 10, "Default", NULL);
 269
 270   // There is no winner yet, so no NameGroupId should be returned.
 271   FieldTrial::ActiveGroup active_group;
 272   EXPECT_FALSE(trial->GetActiveGroup(&active_group));
 273
 274   // Create a single winning group.
 275   std::string one_winner("One Winner");
 276   trial = CreateFieldTrial(one_winner, 10, "Default", NULL);
 277   std::string winner("Winner");
 278   trial->AppendGroup(winner, 10);
 279   EXPECT_FALSE(trial->GetActiveGroup(&active_group));
 280   // Finalize the group selection by accessing the selected group.
 281   trial->group();
 282   EXPECT_TRUE(trial->GetActiveGroup(&active_group));
 283   EXPECT_EQ(one_winner, active_group.trial_name);
 284   EXPECT_EQ(winner, active_group.group_name);
 285
 286   std::string multi_group("MultiGroup");
 287   scoped_refptr<FieldTrial> multi_group_trial =
 288       CreateFieldTrial(multi_group, 9, "Default", NULL);
 289
 290   multi_group_trial->AppendGroup("Me", 3);
 291   multi_group_trial->AppendGroup("You", 3);
 292   multi_group_trial->AppendGroup("Them", 3);
 293   EXPECT_FALSE(multi_group_trial->GetActiveGroup(&active_group));
 294   // Finalize the group selection by accessing the selected group.
 295   multi_group_trial->group();
 296   EXPECT_TRUE(multi_group_trial->GetActiveGroup(&active_group));
 297   EXPECT_EQ(multi_group, active_group.trial_name);
 298   EXPECT_EQ(multi_group_trial->group_name(), active_group.group_name);
 299
 300   // Now check if the list is built properly...
 301   FieldTrial::ActiveGroups active_groups;
 302   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
 303   EXPECT_EQ(2U, active_groups.size());
 304   for (size_t i = 0; i < active_groups.size(); ++i) {
 305     // Order is not guaranteed, so check all values.
 306     EXPECT_NE(no_group, active_groups[i].trial_name);
 307     EXPECT_TRUE(one_winner != active_groups[i].trial_name ||
 308                 winner == active_groups[i].group_name);
 309     EXPECT_TRUE(multi_group != active_groups[i].trial_name ||
 310                 multi_group_trial->group_name() == active_groups[i].group_name);
 311   }
 312 }
 313
 314 TEST_F(FieldTrialTest, ActiveGroupsNotFinalized) {
 315   const char kTrialName[] = "TestTrial";
 316   const char kSecondaryGroupName[] = "SecondaryGroup";
 317
 318   int default_group = -1;
 319   scoped_refptr<FieldTrial> trial =
 320       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, &default_group);
 321   const int secondary_group = trial->AppendGroup(kSecondaryGroupName, 50);
 322
 323   // Before |group()| is called, |GetActiveGroup()| should return false.
 324   FieldTrial::ActiveGroup active_group;
 325   EXPECT_FALSE(trial->GetActiveGroup(&active_group));
 326
 327   // |GetActiveFieldTrialGroups()| should also not include the trial.
 328   FieldTrial::ActiveGroups active_groups;
 329   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
 330   EXPECT_TRUE(active_groups.empty());
 331
 332   // After |group()| has been called, both APIs should succeed.
 333   const int chosen_group = trial->group();
 334   EXPECT_TRUE(chosen_group == default_group || chosen_group == secondary_group);
 335
 336   EXPECT_TRUE(trial->GetActiveGroup(&active_group));
 337   EXPECT_EQ(kTrialName, active_group.trial_name);
 338   if (chosen_group == default_group)
 339     EXPECT_EQ(kDefaultGroupName, active_group.group_name);
 340   else
 341     EXPECT_EQ(kSecondaryGroupName, active_group.group_name);
 342
 343   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
 344   ASSERT_EQ(1U, active_groups.size());
 345   EXPECT_EQ(kTrialName, active_groups[0].trial_name);
 346   EXPECT_EQ(active_group.group_name, active_groups[0].group_name);
 347 }
 348
 349 TEST_F(FieldTrialTest, Save) {
 350   std::string save_string;
 351
 352   scoped_refptr<FieldTrial> trial =
 353       CreateFieldTrial("Some name", 10, "Default some name", NULL);
 354   // There is no winner yet, so no textual group name is associated with trial.
 355   // In this case, the trial should not be included.
 356   EXPECT_EQ("", trial->group_name_internal());
 357   FieldTrialList::StatesToString(&save_string);
 358   EXPECT_EQ("", save_string);
 359   save_string.clear();
 360
 361   // Create a winning group.
 362   trial->AppendGroup("Winner", 10);
 363   // Finalize the group selection by accessing the selected group.
 364   trial->group();
 365   FieldTrialList::StatesToString(&save_string);
 366   EXPECT_EQ("Some name/Winner/", save_string);
 367   save_string.clear();
 368
 369   // Create a second trial and winning group.
 370   scoped_refptr<FieldTrial> trial2 =
 371       CreateFieldTrial("xxx", 10, "Default xxx", NULL);
 372   trial2->AppendGroup("yyyy", 10);
 373   // Finalize the group selection by accessing the selected group.
 374   trial2->group();
 375
 376   FieldTrialList::StatesToString(&save_string);
 377   // We assume names are alphabetized... though this is not critical.
 378   EXPECT_EQ("Some name/Winner/xxx/yyyy/", save_string);
 379   save_string.clear();
 380
 381   // Create a third trial with only the default group.
 382   scoped_refptr<FieldTrial> trial3 =
 383       CreateFieldTrial("zzz", 10, "default", NULL);
 384   // Finalize the group selection by accessing the selected group.
 385   trial3->group();
 386
 387   FieldTrialList::StatesToString(&save_string);
 388   EXPECT_EQ("Some name/Winner/xxx/yyyy/zzz/default/", save_string);
 389 }
 390
 391 TEST_F(FieldTrialTest, Restore) {
 392   ASSERT_FALSE(FieldTrialList::TrialExists("Some_name"));
 393   ASSERT_FALSE(FieldTrialList::TrialExists("xxx"));
 394
 395   FieldTrialList::CreateTrialsFromString("Some_name/Winner/xxx/yyyy/",
 396                                          FieldTrialList::DONT_ACTIVATE_TRIALS,
 397                                          std::set<std::string>());
 398
 399   FieldTrial* trial = FieldTrialList::Find("Some_name");
 400   ASSERT_NE(static_cast<FieldTrial*>(NULL), trial);
 401   EXPECT_EQ("Winner", trial->group_name());
 402   EXPECT_EQ("Some_name", trial->trial_name());
 403
 404   trial = FieldTrialList::Find("xxx");
 405   ASSERT_NE(static_cast<FieldTrial*>(NULL), trial);
 406   EXPECT_EQ("yyyy", trial->group_name());
 407   EXPECT_EQ("xxx", trial->trial_name());
 408 }
 409
 410 TEST_F(FieldTrialTest, RestoreNotEndingWithSlash) {
 411   EXPECT_TRUE(FieldTrialList::CreateTrialsFromString(
 412       "tname/gname", FieldTrialList::DONT_ACTIVATE_TRIALS,
 413       std::set<std::string>()));
 414
 415   FieldTrial* trial = FieldTrialList::Find("tname");
 416   ASSERT_NE(static_cast<FieldTrial*>(NULL), trial);
 417   EXPECT_EQ("gname", trial->group_name());
 418   EXPECT_EQ("tname", trial->trial_name());
 419 }
 420
 421 TEST_F(FieldTrialTest, BogusRestore) {
 422   EXPECT_FALSE(FieldTrialList::CreateTrialsFromString(
 423       "MissingSlash", FieldTrialList::DONT_ACTIVATE_TRIALS,
 424       std::set<std::string>()));
 425   EXPECT_FALSE(FieldTrialList::CreateTrialsFromString(
 426       "MissingGroupName/", FieldTrialList::DONT_ACTIVATE_TRIALS,
 427       std::set<std::string>()));
 428   EXPECT_FALSE(FieldTrialList::CreateTrialsFromString(
 429       "noname, only group/", FieldTrialList::DONT_ACTIVATE_TRIALS,
 430       std::set<std::string>()));
 431   EXPECT_FALSE(FieldTrialList::CreateTrialsFromString(
 432       "/emptyname", FieldTrialList::DONT_ACTIVATE_TRIALS,
 433       std::set<std::string>()));
 434   EXPECT_FALSE(FieldTrialList::CreateTrialsFromString(
 435       "*/emptyname", FieldTrialList::DONT_ACTIVATE_TRIALS,
 436       std::set<std::string>()));
 437 }
 438
 439 TEST_F(FieldTrialTest, DuplicateRestore) {
 440   scoped_refptr<FieldTrial> trial =
 441       CreateFieldTrial("Some name", 10, "Default", NULL);
 442   trial->AppendGroup("Winner", 10);
 443   // Finalize the group selection by accessing the selected group.
 444   trial->group();
 445   std::string save_string;
 446   FieldTrialList::StatesToString(&save_string);
 447   EXPECT_EQ("Some name/Winner/", save_string);
 448
 449   // It is OK if we redundantly specify a winner.
 450   EXPECT_TRUE(FieldTrialList::CreateTrialsFromString(
 451       save_string, FieldTrialList::DONT_ACTIVATE_TRIALS,
 452       std::set<std::string>()));
 453
 454   // But it is an error to try to change to a different winner.
 455   EXPECT_FALSE(FieldTrialList::CreateTrialsFromString(
 456       "Some name/Loser/", FieldTrialList::DONT_ACTIVATE_TRIALS,
 457       std::set<std::string>()));
 458 }
 459
 460 TEST_F(FieldTrialTest, CreateTrialsFromStringActive) {
 461   ASSERT_FALSE(FieldTrialList::TrialExists("Abc"));
 462   ASSERT_FALSE(FieldTrialList::TrialExists("Xyz"));
 463   ASSERT_TRUE(FieldTrialList::CreateTrialsFromString(
 464       "Abc/def/Xyz/zyx/", FieldTrialList::ACTIVATE_TRIALS,
 465       std::set<std::string>()));
 466
 467   FieldTrial::ActiveGroups active_groups;
 468   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
 469   ASSERT_EQ(2U, active_groups.size());
 470   EXPECT_EQ("Abc", active_groups[0].trial_name);
 471   EXPECT_EQ("def", active_groups[0].group_name);
 472   EXPECT_EQ("Xyz", active_groups[1].trial_name);
 473   EXPECT_EQ("zyx", active_groups[1].group_name);
 474 }
 475
 476 TEST_F(FieldTrialTest, CreateTrialsFromStringNotActive) {
 477   ASSERT_FALSE(FieldTrialList::TrialExists("Abc"));
 478   ASSERT_FALSE(FieldTrialList::TrialExists("Xyz"));
 479   ASSERT_TRUE(FieldTrialList::CreateTrialsFromString(
 480       "Abc/def/Xyz/zyx/", FieldTrialList::DONT_ACTIVATE_TRIALS,
 481       std::set<std::string>()));
 482
 483   FieldTrial::ActiveGroups active_groups;
 484   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
 485   ASSERT_TRUE(active_groups.empty());
 486
 487   // Check that the values still get returned and querying them activates them.
 488   EXPECT_EQ("def", FieldTrialList::FindFullName("Abc"));
 489   EXPECT_EQ("zyx", FieldTrialList::FindFullName("Xyz"));
 490
 491   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
 492   ASSERT_EQ(2U, active_groups.size());
 493   EXPECT_EQ("Abc", active_groups[0].trial_name);
 494   EXPECT_EQ("def", active_groups[0].group_name);
 495   EXPECT_EQ("Xyz", active_groups[1].trial_name);
 496   EXPECT_EQ("zyx", active_groups[1].group_name);
 497 }
 498
 499 TEST_F(FieldTrialTest, CreateTrialsFromStringForceActivation) {
 500   ASSERT_FALSE(FieldTrialList::TrialExists("Abc"));
 501   ASSERT_FALSE(FieldTrialList::TrialExists("def"));
 502   ASSERT_FALSE(FieldTrialList::TrialExists("Xyz"));
 503   ASSERT_TRUE(FieldTrialList::CreateTrialsFromString(
 504       "*Abc/cba/def/fed/*Xyz/zyx/", FieldTrialList::DONT_ACTIVATE_TRIALS,
 505       std::set<std::string>()));
 506
 507   FieldTrial::ActiveGroups active_groups;
 508   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
 509   ASSERT_EQ(2U, active_groups.size());
 510   EXPECT_EQ("Abc", active_groups[0].trial_name);
 511   EXPECT_EQ("cba", active_groups[0].group_name);
 512   EXPECT_EQ("Xyz", active_groups[1].trial_name);
 513   EXPECT_EQ("zyx", active_groups[1].group_name);
 514 }
 515
 516 TEST_F(FieldTrialTest, CreateTrialsFromStringActiveObserver) {
 517   ASSERT_FALSE(FieldTrialList::TrialExists("Abc"));
 518
 519   TestFieldTrialObserver observer;
 520   ASSERT_TRUE(FieldTrialList::CreateTrialsFromString(
 521       "Abc/def/", FieldTrialList::ACTIVATE_TRIALS, std::set<std::string>()));
 522
 523   RunLoop().RunUntilIdle();
 524   EXPECT_EQ("Abc", observer.trial_name());
 525   EXPECT_EQ("def", observer.group_name());
 526 }
 527
 528 TEST_F(FieldTrialTest, CreateTrialsFromStringNotActiveObserver) {
 529   ASSERT_FALSE(FieldTrialList::TrialExists("Abc"));
 530
 531   TestFieldTrialObserver observer;
 532   ASSERT_TRUE(FieldTrialList::CreateTrialsFromString(
 533       "Abc/def/", FieldTrialList::DONT_ACTIVATE_TRIALS,
 534       std::set<std::string>()));
 535   RunLoop().RunUntilIdle();
 536   // Observer shouldn't be notified.
 537   EXPECT_TRUE(observer.trial_name().empty());
 538
 539   // Check that the values still get returned and querying them activates them.
 540   EXPECT_EQ("def", FieldTrialList::FindFullName("Abc"));
 541
 542   RunLoop().RunUntilIdle();
 543   EXPECT_EQ("Abc", observer.trial_name());
 544   EXPECT_EQ("def", observer.group_name());
 545 }
 546
 547 TEST_F(FieldTrialTest, CreateTrialsFromStringWithIgnoredFieldTrials) {
 548   ASSERT_FALSE(FieldTrialList::TrialExists("Unaccepted1"));
 549   ASSERT_FALSE(FieldTrialList::TrialExists("Foo"));
 550   ASSERT_FALSE(FieldTrialList::TrialExists("Unaccepted2"));
 551   ASSERT_FALSE(FieldTrialList::TrialExists("Bar"));
 552   ASSERT_FALSE(FieldTrialList::TrialExists("Unaccepted3"));
 553
 554   std::set<std::string> ignored_trial_names;
 555   ignored_trial_names.insert("Unaccepted1");
 556   ignored_trial_names.insert("Unaccepted2");
 557   ignored_trial_names.insert("Unaccepted3");
 558
 559   FieldTrialList::CreateTrialsFromString(
 560       "Unaccepted1/Unaccepted1_name/"
 561       "Foo/Foo_name/"
 562       "Unaccepted2/Unaccepted2_name/"
 563       "Bar/Bar_name/"
 564       "Unaccepted3/Unaccepted3_name/",
 565       FieldTrialList::DONT_ACTIVATE_TRIALS,
 566       ignored_trial_names);
 567
 568   EXPECT_FALSE(FieldTrialList::TrialExists("Unaccepted1"));
 569   EXPECT_TRUE(FieldTrialList::TrialExists("Foo"));
 570   EXPECT_FALSE(FieldTrialList::TrialExists("Unaccepted2"));
 571   EXPECT_TRUE(FieldTrialList::TrialExists("Bar"));
 572   EXPECT_FALSE(FieldTrialList::TrialExists("Unaccepted3"));
 573
 574   FieldTrial::ActiveGroups active_groups;
 575   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
 576   EXPECT_TRUE(active_groups.empty());
 577
 578   FieldTrial* trial = FieldTrialList::Find("Foo");
 579   ASSERT_NE(static_cast<FieldTrial*>(NULL), trial);
 580   EXPECT_EQ("Foo", trial->trial_name());
 581   EXPECT_EQ("Foo_name", trial->group_name());
 582
 583   trial = FieldTrialList::Find("Bar");
 584   ASSERT_NE(static_cast<FieldTrial*>(NULL), trial);
 585   EXPECT_EQ("Bar", trial->trial_name());
 586   EXPECT_EQ("Bar_name", trial->group_name());
 587 }
 588
 589 TEST_F(FieldTrialTest, CreateFieldTrial) {
 590   ASSERT_FALSE(FieldTrialList::TrialExists("Some_name"));
 591
 592   FieldTrialList::CreateFieldTrial("Some_name", "Winner");
 593
 594   FieldTrial* trial = FieldTrialList::Find("Some_name");
 595   ASSERT_NE(static_cast<FieldTrial*>(NULL), trial);
 596   EXPECT_EQ("Winner", trial->group_name());
 597   EXPECT_EQ("Some_name", trial->trial_name());
 598 }
 599
 600 TEST_F(FieldTrialTest, CreateFieldTrialIsNotActive) {
 601   const char kTrialName[] = "CreateFieldTrialIsActiveTrial";
 602   const char kWinnerGroup[] = "Winner";
 603   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
 604   FieldTrialList::CreateFieldTrial(kTrialName, kWinnerGroup);
 605
 606   FieldTrial::ActiveGroups active_groups;
 607   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
 608   EXPECT_TRUE(active_groups.empty());
 609 }
 610
 611 TEST_F(FieldTrialTest, DuplicateFieldTrial) {
 612   scoped_refptr<FieldTrial> trial =
 613       CreateFieldTrial("Some_name", 10, "Default", NULL);
 614   trial->AppendGroup("Winner", 10);
 615
 616   // It is OK if we redundantly specify a winner.
 617   FieldTrial* trial1 = FieldTrialList::CreateFieldTrial("Some_name", "Winner");
 618   EXPECT_TRUE(trial1 != NULL);
 619
 620   // But it is an error to try to change to a different winner.
 621   FieldTrial* trial2 = FieldTrialList::CreateFieldTrial("Some_name", "Loser");
 622   EXPECT_TRUE(trial2 == NULL);
 623 }
 624
 625 TEST_F(FieldTrialTest, DisableImmediately) {
 626   int default_group_number = -1;
 627   scoped_refptr<FieldTrial> trial =
 628       CreateFieldTrial("trial", 100, "default", &default_group_number);
 629   trial->Disable();
 630   ASSERT_EQ("default", trial->group_name());
 631   ASSERT_EQ(default_group_number, trial->group());
 632 }
 633
 634 TEST_F(FieldTrialTest, DisableAfterInitialization) {
 635   scoped_refptr<FieldTrial> trial =
 636       CreateFieldTrial("trial", 100, "default", NULL);
 637   trial->AppendGroup("non_default", 100);
 638   trial->Disable();
 639   ASSERT_EQ("default", trial->group_name());
 640 }
 641
 642 TEST_F(FieldTrialTest, ForcedFieldTrials) {
 643   // Validate we keep the forced choice.
 644   FieldTrial* forced_trial = FieldTrialList::CreateFieldTrial("Use the",
 645                                                               "Force");
 646   EXPECT_STREQ("Force", forced_trial->group_name().c_str());
 647
 648   int default_group_number = -1;
 649   scoped_refptr<FieldTrial> factory_trial =
 650       CreateFieldTrial("Use the", 1000, "default", &default_group_number);
 651   EXPECT_EQ(factory_trial.get(), forced_trial);
 652
 653   int chosen_group = factory_trial->AppendGroup("Force", 100);
 654   EXPECT_EQ(chosen_group, factory_trial->group());
 655   int not_chosen_group = factory_trial->AppendGroup("Dark Side", 100);
 656   EXPECT_NE(chosen_group, not_chosen_group);
 657
 658   // Since we didn't force the default group, we should not be returned the
 659   // chosen group as the default group.
 660   EXPECT_NE(default_group_number, chosen_group);
 661   int new_group = factory_trial->AppendGroup("Duck Tape", 800);
 662   EXPECT_NE(chosen_group, new_group);
 663   // The new group should not be the default group either.
 664   EXPECT_NE(default_group_number, new_group);
 665 }
 666
 667 TEST_F(FieldTrialTest, ForcedFieldTrialsDefaultGroup) {
 668   // Forcing the default should use the proper group ID.
 669   FieldTrial* forced_trial = FieldTrialList::CreateFieldTrial("Trial Name",
 670                                                               "Default");
 671   int default_group_number = -1;
 672   scoped_refptr<FieldTrial> factory_trial =
 673       CreateFieldTrial("Trial Name", 1000, "Default", &default_group_number);
 674   EXPECT_EQ(forced_trial, factory_trial.get());
 675
 676   int other_group = factory_trial->AppendGroup("Not Default", 100);
 677   EXPECT_STREQ("Default", factory_trial->group_name().c_str());
 678   EXPECT_EQ(default_group_number, factory_trial->group());
 679   EXPECT_NE(other_group, factory_trial->group());
 680
 681   int new_other_group = factory_trial->AppendGroup("Not Default Either", 800);
 682   EXPECT_NE(new_other_group, factory_trial->group());
 683 }
 684
 685 TEST_F(FieldTrialTest, SetForced) {
 686   // Start by setting a trial for which we ensure a winner...
 687   int default_group_number = -1;
 688   scoped_refptr<FieldTrial> forced_trial =
 689       CreateFieldTrial("Use the", 1, "default", &default_group_number);
 690   EXPECT_EQ(forced_trial, forced_trial);
 691
 692   int forced_group = forced_trial->AppendGroup("Force", 1);
 693   EXPECT_EQ(forced_group, forced_trial->group());
 694
 695   // Now force it.
 696   forced_trial->SetForced();
 697
 698   // Now try to set it up differently as a hard coded registration would.
 699   scoped_refptr<FieldTrial> hard_coded_trial =
 700       CreateFieldTrial("Use the", 1, "default", &default_group_number);
 701   EXPECT_EQ(hard_coded_trial, forced_trial);
 702
 703   int would_lose_group = hard_coded_trial->AppendGroup("Force", 0);
 704   EXPECT_EQ(forced_group, hard_coded_trial->group());
 705   EXPECT_EQ(forced_group, would_lose_group);
 706
 707   // Same thing if we would have done it to win again.
 708   scoped_refptr<FieldTrial> other_hard_coded_trial =
 709       CreateFieldTrial("Use the", 1, "default", &default_group_number);
 710   EXPECT_EQ(other_hard_coded_trial, forced_trial);
 711
 712   int would_win_group = other_hard_coded_trial->AppendGroup("Force", 1);
 713   EXPECT_EQ(forced_group, other_hard_coded_trial->group());
 714   EXPECT_EQ(forced_group, would_win_group);
 715 }
 716
 717 TEST_F(FieldTrialTest, SetForcedDefaultOnly) {
 718   const char kTrialName[] = "SetForcedDefaultOnly";
 719   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
 720
 721   int default_group = -1;
 722   scoped_refptr<FieldTrial> trial =
 723       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, &default_group);
 724   trial->SetForced();
 725
 726   trial = CreateFieldTrial(kTrialName, 100, kDefaultGroupName, NULL);
 727   EXPECT_EQ(default_group, trial->group());
 728   EXPECT_EQ(kDefaultGroupName, trial->group_name());
 729 }
 730
 731 TEST_F(FieldTrialTest, SetForcedDefaultWithExtraGroup) {
 732   const char kTrialName[] = "SetForcedDefaultWithExtraGroup";
 733   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
 734
 735   int default_group = -1;
 736   scoped_refptr<FieldTrial> trial =
 737       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, &default_group);
 738   trial->SetForced();
 739
 740   trial = CreateFieldTrial(kTrialName, 100, kDefaultGroupName, NULL);
 741   const int extra_group = trial->AppendGroup("Extra", 100);
 742   EXPECT_EQ(default_group, trial->group());
 743   EXPECT_NE(extra_group, trial->group());
 744   EXPECT_EQ(kDefaultGroupName, trial->group_name());
 745 }
 746
 747 TEST_F(FieldTrialTest, SetForcedTurnFeatureOn) {
 748   const char kTrialName[] = "SetForcedTurnFeatureOn";
 749   const char kExtraGroupName[] = "Extra";
 750   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
 751
 752   // Simulate a server-side (forced) config that turns the feature on when the
 753   // original hard-coded config had it disabled.
 754   scoped_refptr<FieldTrial> forced_trial =
 755       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, NULL);
 756   forced_trial->AppendGroup(kExtraGroupName, 100);
 757   forced_trial->SetForced();
 758
 759   int default_group = -1;
 760   scoped_refptr<FieldTrial> client_trial =
 761       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, &default_group);
 762   const int extra_group = client_trial->AppendGroup(kExtraGroupName, 0);
 763   EXPECT_NE(default_group, extra_group);
 764
 765   EXPECT_FALSE(client_trial->group_reported_);
 766   EXPECT_EQ(extra_group, client_trial->group());
 767   EXPECT_TRUE(client_trial->group_reported_);
 768   EXPECT_EQ(kExtraGroupName, client_trial->group_name());
 769 }
 770
 771 TEST_F(FieldTrialTest, SetForcedTurnFeatureOff) {
 772   const char kTrialName[] = "SetForcedTurnFeatureOff";
 773   const char kExtraGroupName[] = "Extra";
 774   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
 775
 776   // Simulate a server-side (forced) config that turns the feature off when the
 777   // original hard-coded config had it enabled.
 778   scoped_refptr<FieldTrial> forced_trial =
 779       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, NULL);
 780   forced_trial->AppendGroup(kExtraGroupName, 0);
 781   forced_trial->SetForced();
 782
 783   int default_group = -1;
 784   scoped_refptr<FieldTrial> client_trial =
 785       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, &default_group);
 786   const int extra_group = client_trial->AppendGroup(kExtraGroupName, 100);
 787   EXPECT_NE(default_group, extra_group);
 788
 789   EXPECT_FALSE(client_trial->group_reported_);
 790   EXPECT_EQ(default_group, client_trial->group());
 791   EXPECT_TRUE(client_trial->group_reported_);
 792   EXPECT_EQ(kDefaultGroupName, client_trial->group_name());
 793 }
 794
 795 TEST_F(FieldTrialTest, SetForcedChangeDefault_Default) {
 796   const char kTrialName[] = "SetForcedDefaultGroupChange";
 797   const char kGroupAName[] = "A";
 798   const char kGroupBName[] = "B";
 799   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
 800
 801   // Simulate a server-side (forced) config that switches which group is default
 802   // and ensures that the non-forced code receives the correct group numbers.
 803   scoped_refptr<FieldTrial> forced_trial =
 804       CreateFieldTrial(kTrialName, 100, kGroupAName, NULL);
 805   forced_trial->AppendGroup(kGroupBName, 100);
 806   forced_trial->SetForced();
 807
 808   int default_group = -1;
 809   scoped_refptr<FieldTrial> client_trial =
 810       CreateFieldTrial(kTrialName, 100, kGroupBName, &default_group);
 811   const int extra_group = client_trial->AppendGroup(kGroupAName, 50);
 812   EXPECT_NE(default_group, extra_group);
 813
 814   EXPECT_FALSE(client_trial->group_reported_);
 815   EXPECT_EQ(default_group, client_trial->group());
 816   EXPECT_TRUE(client_trial->group_reported_);
 817   EXPECT_EQ(kGroupBName, client_trial->group_name());
 818 }
 819
 820 TEST_F(FieldTrialTest, SetForcedChangeDefault_NonDefault) {
 821   const char kTrialName[] = "SetForcedDefaultGroupChange";
 822   const char kGroupAName[] = "A";
 823   const char kGroupBName[] = "B";
 824   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
 825
 826   // Simulate a server-side (forced) config that switches which group is default
 827   // and ensures that the non-forced code receives the correct group numbers.
 828   scoped_refptr<FieldTrial> forced_trial =
 829       CreateFieldTrial(kTrialName, 100, kGroupAName, NULL);
 830   forced_trial->AppendGroup(kGroupBName, 0);
 831   forced_trial->SetForced();
 832
 833   int default_group = -1;
 834   scoped_refptr<FieldTrial> client_trial =
 835       CreateFieldTrial(kTrialName, 100, kGroupBName, &default_group);
 836   const int extra_group = client_trial->AppendGroup(kGroupAName, 50);
 837   EXPECT_NE(default_group, extra_group);
 838
 839   EXPECT_FALSE(client_trial->group_reported_);
 840   EXPECT_EQ(extra_group, client_trial->group());
 841   EXPECT_TRUE(client_trial->group_reported_);
 842   EXPECT_EQ(kGroupAName, client_trial->group_name());
 843 }
 844
 845 TEST_F(FieldTrialTest, Observe) {
 846   const char kTrialName[] = "TrialToObserve1";
 847   const char kSecondaryGroupName[] = "SecondaryGroup";
 848
 849   TestFieldTrialObserver observer;
 850   int default_group = -1;
 851   scoped_refptr<FieldTrial> trial =
 852       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, &default_group);
 853   const int secondary_group = trial->AppendGroup(kSecondaryGroupName, 50);
 854   const int chosen_group = trial->group();
 855   EXPECT_TRUE(chosen_group == default_group || chosen_group == secondary_group);
 856
 857   RunLoop().RunUntilIdle();
 858   EXPECT_EQ(kTrialName, observer.trial_name());
 859   if (chosen_group == default_group)
 860     EXPECT_EQ(kDefaultGroupName, observer.group_name());
 861   else
 862     EXPECT_EQ(kSecondaryGroupName, observer.group_name());
 863 }
 864
 865 TEST_F(FieldTrialTest, ObserveDisabled) {
 866   const char kTrialName[] = "TrialToObserve2";
 867
 868   TestFieldTrialObserver observer;
 869   int default_group = -1;
 870   scoped_refptr<FieldTrial> trial =
 871       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, &default_group);
 872   trial->AppendGroup("A", 25);
 873   trial->AppendGroup("B", 25);
 874   trial->AppendGroup("C", 25);
 875   trial->Disable();
 876
 877   // Observer shouldn't be notified of a disabled trial.
 878   RunLoop().RunUntilIdle();
 879   EXPECT_TRUE(observer.trial_name().empty());
 880   EXPECT_TRUE(observer.group_name().empty());
 881
 882   // Observer shouldn't be notified even after a |group()| call.
 883   EXPECT_EQ(default_group, trial->group());
 884   RunLoop().RunUntilIdle();
 885   EXPECT_TRUE(observer.trial_name().empty());
 886   EXPECT_TRUE(observer.group_name().empty());
 887 }
 888
 889 TEST_F(FieldTrialTest, ObserveForcedDisabled) {
 890   const char kTrialName[] = "TrialToObserve3";
 891
 892   TestFieldTrialObserver observer;
 893   int default_group = -1;
 894   scoped_refptr<FieldTrial> trial =
 895       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, &default_group);
 896   trial->AppendGroup("A", 25);
 897   trial->AppendGroup("B", 25);
 898   trial->AppendGroup("C", 25);
 899   trial->SetForced();
 900   trial->Disable();
 901
 902   // Observer shouldn't be notified of a disabled trial, even when forced.
 903   RunLoop().RunUntilIdle();
 904   EXPECT_TRUE(observer.trial_name().empty());
 905   EXPECT_TRUE(observer.group_name().empty());
 906
 907   // Observer shouldn't be notified even after a |group()| call.
 908   EXPECT_EQ(default_group, trial->group());
 909   RunLoop().RunUntilIdle();
 910   EXPECT_TRUE(observer.trial_name().empty());
 911   EXPECT_TRUE(observer.group_name().empty());
 912 }
 913
 914 TEST_F(FieldTrialTest, DisabledTrialNotActive) {
 915   const char kTrialName[] = "DisabledTrial";
 916   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
 917
 918   scoped_refptr<FieldTrial> trial =
 919       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, NULL);
 920   trial->AppendGroup("X", 50);
 921   trial->Disable();
 922
 923   // Ensure the trial is not listed as active.
 924   FieldTrial::ActiveGroups active_groups;
 925   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
 926   EXPECT_TRUE(active_groups.empty());
 927
 928   // Ensure the trial is not listed in the |StatesToString()| result.
 929   std::string states;
 930   FieldTrialList::StatesToString(&states);
 931   EXPECT_TRUE(states.empty());
 932 }
 933
 934 TEST_F(FieldTrialTest, ExpirationYearNotExpired) {
 935   const char kTrialName[] = "NotExpired";
 936   const char kGroupName[] = "Group2";
 937   const int kProbability = 100;
 938   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
 939
 940   scoped_refptr<FieldTrial> trial =
 941       CreateFieldTrial(kTrialName, kProbability, kDefaultGroupName, NULL);
 942   trial->AppendGroup(kGroupName, kProbability);
 943   EXPECT_EQ(kGroupName, trial->group_name());
 944 }
 945
 946 TEST_F(FieldTrialTest, FloatBoundariesGiveEqualGroupSizes) {
 947   const int kBucketCount = 100;
 948
 949   // Try each boundary value |i / 100.0| as the entropy value.
 950   for (int i = 0; i < kBucketCount; ++i) {
 951     const double entropy = i / static_cast<double>(kBucketCount);
 952
 953     scoped_refptr<base::FieldTrial> trial(
 954         new base::FieldTrial("test", kBucketCount, "default", entropy));
 955     for (int j = 0; j < kBucketCount; ++j)
 956       trial->AppendGroup(base::StringPrintf("%d", j), 1);
 957
 958     EXPECT_EQ(base::StringPrintf("%d", i), trial->group_name());
 959   }
 960 }
 961
 962 TEST_F(FieldTrialTest, DoesNotSurpassTotalProbability) {
 963   const double kEntropyValue = 1.0 - 1e-9;
 964   ASSERT_LT(kEntropyValue, 1.0);
 965
 966   scoped_refptr<base::FieldTrial> trial(
 967       new base::FieldTrial("test", 2, "default", kEntropyValue));
 968   trial->AppendGroup("1", 1);
 969   trial->AppendGroup("2", 1);
 970
 971   EXPECT_EQ("2", trial->group_name());
 972 }
 973
 974 TEST_F(FieldTrialTest, CreateSimulatedFieldTrial) {
 975   const char kTrialName[] = "CreateSimulatedFieldTrial";
 976   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
 977
 978   // Different cases to test, e.g. default vs. non default group being chosen.
 979   struct {
 980     double entropy_value;
 981     const char* expected_group;
 982   } test_cases[] = {
 983     { 0.4, "A" },
 984     { 0.85, "B" },
 985     { 0.95, kDefaultGroupName },
 986   };
 987
 988   for (size_t i = 0; i < arraysize(test_cases); ++i) {
 989     TestFieldTrialObserver observer;
 990     scoped_refptr<FieldTrial> trial(
 991        FieldTrial::CreateSimulatedFieldTrial(kTrialName, 100, kDefaultGroupName,
 992                                              test_cases[i].entropy_value));
 993     trial->AppendGroup("A", 80);
 994     trial->AppendGroup("B", 10);
 995     EXPECT_EQ(test_cases[i].expected_group, trial->group_name());
 996
 997     // Field trial shouldn't have been registered with the list.
 998     EXPECT_FALSE(FieldTrialList::TrialExists(kTrialName));
 999     EXPECT_EQ(0u, FieldTrialList::GetFieldTrialCount());
1000
1001     // Observer shouldn't have been notified.
1002     RunLoop().RunUntilIdle();
1003     EXPECT_TRUE(observer.trial_name().empty());
1004
1005     // The trial shouldn't be in the active set of trials.
1006     FieldTrial::ActiveGroups active_groups;
1007     FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
1008     EXPECT_TRUE(active_groups.empty());
1009
1010     // The trial shouldn't be listed in the |StatesToString()| result.
1011     std::string states;
1012     FieldTrialList::StatesToString(&states);
1013     EXPECT_TRUE(states.empty());
1014   }
1015 }
1016
1017 #if GTEST_HAS_DEATH_TEST
1018 TEST(FieldTrialDeathTest, OneTimeRandomizedTrialWithoutFieldTrialList) {
1019   // Trying to instantiate a one-time randomized field trial before the
1020   // FieldTrialList is created should crash.
1021   EXPECT_DEATH(FieldTrialList::FactoryGetFieldTrial(
1022       "OneTimeRandomizedTrialWithoutFieldTrialList", 100, kDefaultGroupName,
1023       base::FieldTrialList::kNoExpirationYear, 1, 1,
1024       base::FieldTrial::ONE_TIME_RANDOMIZED, NULL), "");
1025 }
1026 #endif
1027
1028 }  // namespace base