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      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 <stddef.h>
      8 
      9 #include "base/build_time.h"
     10 #include "base/macros.h"
     11 #include "base/message_loop/message_loop.h"
     12 #include "base/rand_util.h"
     13 #include "base/run_loop.h"
     14 #include "base/strings/string_number_conversions.h"
     15 #include "base/strings/stringprintf.h"
     16 #include "testing/gtest/include/gtest/gtest.h"
     17 
     18 namespace base {
     19 
     20 namespace {
     21 
     22 // Default group name used by several tests.
     23 const char kDefaultGroupName[] = "DefaultGroup";
     24 
     25 // Call FieldTrialList::FactoryGetFieldTrial() with a future expiry date.
     26 scoped_refptr<base::FieldTrial> CreateFieldTrial(
     27     const std::string& trial_name,
     28     int total_probability,
     29     const std::string& default_group_name,
     30     int* default_group_number) {
     31   return FieldTrialList::FactoryGetFieldTrial(
     32       trial_name, total_probability, default_group_name,
     33       base::FieldTrialList::kNoExpirationYear, 1, 1,
     34       base::FieldTrial::SESSION_RANDOMIZED, default_group_number);
     35 }
     36 
     37 int OneYearBeforeBuildTime() {
     38   Time one_year_before_build_time = GetBuildTime() - TimeDelta::FromDays(365);
     39   Time::Exploded exploded;
     40   one_year_before_build_time.LocalExplode(&exploded);
     41   return exploded.year;
     42 }
     43 
     44 // FieldTrialList::Observer implementation for testing.
     45 class TestFieldTrialObserver : public FieldTrialList::Observer {
     46  public:
     47   TestFieldTrialObserver() {
     48     FieldTrialList::AddObserver(this);
     49   }
     50 
     51   ~TestFieldTrialObserver() override { FieldTrialList::RemoveObserver(this); }
     52 
     53   void OnFieldTrialGroupFinalized(const std::string& trial,
     54                                   const std::string& group) override {
     55     trial_name_ = trial;
     56     group_name_ = group;
     57   }
     58 
     59   const std::string& trial_name() const { return trial_name_; }
     60   const std::string& group_name() const { return group_name_; }
     61 
     62  private:
     63   std::string trial_name_;
     64   std::string group_name_;
     65 
     66   DISALLOW_COPY_AND_ASSIGN(TestFieldTrialObserver);
     67 };
     68 
     69 }  // namespace
     70 
     71 class FieldTrialTest : public testing::Test {
     72  public:
     73   FieldTrialTest() : trial_list_(NULL) {}
     74 
     75  private:
     76   MessageLoop message_loop_;
     77   FieldTrialList trial_list_;
     78 
     79   DISALLOW_COPY_AND_ASSIGN(FieldTrialTest);
     80 };
     81 
     82 // Test registration, and also check that destructors are called for trials
     83 // (and that Valgrind doesn't catch us leaking).
     84 TEST_F(FieldTrialTest, Registration) {
     85   const char name1[] = "name 1 test";
     86   const char name2[] = "name 2 test";
     87   EXPECT_FALSE(FieldTrialList::Find(name1));
     88   EXPECT_FALSE(FieldTrialList::Find(name2));
     89 
     90   scoped_refptr<FieldTrial> trial1 =
     91       CreateFieldTrial(name1, 10, "default name 1 test", NULL);
     92   EXPECT_EQ(FieldTrial::kNotFinalized, trial1->group_);
     93   EXPECT_EQ(name1, trial1->trial_name());
     94   EXPECT_EQ("", trial1->group_name_internal());
     95 
     96   trial1->AppendGroup(std::string(), 7);
     97 
     98   EXPECT_EQ(trial1.get(), FieldTrialList::Find(name1));
     99   EXPECT_FALSE(FieldTrialList::Find(name2));
    100 
    101   scoped_refptr<FieldTrial> trial2 =
    102       CreateFieldTrial(name2, 10, "default name 2 test", NULL);
    103   EXPECT_EQ(FieldTrial::kNotFinalized, trial2->group_);
    104   EXPECT_EQ(name2, trial2->trial_name());
    105   EXPECT_EQ("", trial2->group_name_internal());
    106 
    107   trial2->AppendGroup("a first group", 7);
    108 
    109   EXPECT_EQ(trial1.get(), FieldTrialList::Find(name1));
    110   EXPECT_EQ(trial2.get(), FieldTrialList::Find(name2));
    111   // Note: FieldTrialList should delete the objects at shutdown.
    112 }
    113 
    114 TEST_F(FieldTrialTest, AbsoluteProbabilities) {
    115   char always_true[] = " always true";
    116   char default_always_true[] = " default always true";
    117   char always_false[] = " always false";
    118   char default_always_false[] = " default always false";
    119   for (int i = 1; i < 250; ++i) {
    120     // Try lots of names, by changing the first character of the name.
    121     char c = static_cast<char>(i);
    122     always_true[0] = c;
    123     default_always_true[0] = c;
    124     always_false[0] = c;
    125     default_always_false[0] = c;
    126 
    127     scoped_refptr<FieldTrial> trial_true =
    128         CreateFieldTrial(always_true, 10, default_always_true, NULL);
    129     const std::string winner = "TheWinner";
    130     int winner_group = trial_true->AppendGroup(winner, 10);
    131 
    132     EXPECT_EQ(winner_group, trial_true->group());
    133     EXPECT_EQ(winner, trial_true->group_name());
    134 
    135     scoped_refptr<FieldTrial> trial_false =
    136         CreateFieldTrial(always_false, 10, default_always_false, NULL);
    137     int loser_group = trial_false->AppendGroup("ALoser", 0);
    138 
    139     EXPECT_NE(loser_group, trial_false->group());
    140   }
    141 }
    142 
    143 TEST_F(FieldTrialTest, RemainingProbability) {
    144   // First create a test that hasn't had a winner yet.
    145   const std::string winner = "Winner";
    146   const std::string loser = "Loser";
    147   scoped_refptr<FieldTrial> trial;
    148   int counter = 0;
    149   int default_group_number = -1;
    150   do {
    151     std::string name = StringPrintf("trial%d", ++counter);
    152     trial = CreateFieldTrial(name, 10, winner, &default_group_number);
    153     trial->AppendGroup(loser, 5);  // 50% chance of not being chosen.
    154     // If a group is not assigned, group_ will be kNotFinalized.
    155   } while (trial->group_ != FieldTrial::kNotFinalized);
    156 
    157   // And that 'default' group (winner) should always win.
    158   EXPECT_EQ(default_group_number, trial->group());
    159 
    160   // And that winner should ALWAYS win.
    161   EXPECT_EQ(winner, trial->group_name());
    162 }
    163 
    164 TEST_F(FieldTrialTest, FiftyFiftyProbability) {
    165   // Check that even with small divisors, we have the proper probabilities, and
    166   // all outcomes are possible.  Since this is a 50-50 test, it should get both
    167   // outcomes in a few tries, but we'll try no more than 100 times (and be flaky
    168   // with probability around 1 in 2^99).
    169   bool first_winner = false;
    170   bool second_winner = false;
    171   int counter = 0;
    172   do {
    173     std::string name = base::StringPrintf("FiftyFifty%d", ++counter);
    174     std::string default_group_name = base::StringPrintf("Default FiftyFifty%d",
    175                                                         ++counter);
    176     scoped_refptr<FieldTrial> trial =
    177         CreateFieldTrial(name, 2, default_group_name, NULL);
    178     trial->AppendGroup("first", 1);  // 50% chance of being chosen.
    179     // If group_ is kNotFinalized, then a group assignement hasn't been done.
    180     if (trial->group_ != FieldTrial::kNotFinalized) {
    181       first_winner = true;
    182       continue;
    183     }
    184     trial->AppendGroup("second", 1);  // Always chosen at this point.
    185     EXPECT_NE(FieldTrial::kNotFinalized, trial->group());
    186     second_winner = true;
    187   } while ((!second_winner || !first_winner) && counter < 100);
    188   EXPECT_TRUE(second_winner);
    189   EXPECT_TRUE(first_winner);
    190 }
    191 
    192 TEST_F(FieldTrialTest, MiddleProbabilities) {
    193   char name[] = " same name";
    194   char default_group_name[] = " default same name";
    195   bool false_event_seen = false;
    196   bool true_event_seen = false;
    197   for (int i = 1; i < 250; ++i) {
    198     char c = static_cast<char>(i);
    199     name[0] = c;
    200     default_group_name[0] = c;
    201     scoped_refptr<FieldTrial> trial =
    202         CreateFieldTrial(name, 10, default_group_name, NULL);
    203     int might_win = trial->AppendGroup("MightWin", 5);
    204 
    205     if (trial->group() == might_win) {
    206       true_event_seen = true;
    207     } else {
    208       false_event_seen = true;
    209     }
    210     if (false_event_seen && true_event_seen)
    211       return;  // Successful test!!!
    212   }
    213   // Very surprising to get here. Probability should be around 1 in 2 ** 250.
    214   // One of the following will fail.
    215   EXPECT_TRUE(false_event_seen);
    216   EXPECT_TRUE(true_event_seen);
    217 }
    218 
    219 TEST_F(FieldTrialTest, OneWinner) {
    220   char name[] = "Some name";
    221   char default_group_name[] = "Default some name";
    222   int group_count(10);
    223 
    224   int default_group_number = -1;
    225   scoped_refptr<FieldTrial> trial =
    226       CreateFieldTrial(name, group_count, default_group_name, NULL);
    227   int winner_index(-2);
    228   std::string winner_name;
    229 
    230   for (int i = 1; i <= group_count; ++i) {
    231     int might_win = trial->AppendGroup(std::string(), 1);
    232 
    233     // Because we keep appending groups, we want to see if the last group that
    234     // was added has been assigned or not.
    235     if (trial->group_ == might_win) {
    236       EXPECT_EQ(-2, winner_index);
    237       winner_index = might_win;
    238       StringAppendF(&winner_name, "%d", might_win);
    239       EXPECT_EQ(winner_name, trial->group_name());
    240     }
    241   }
    242   EXPECT_GE(winner_index, 0);
    243   // Since all groups cover the total probability, we should not have
    244   // chosen the default group.
    245   EXPECT_NE(trial->group(), default_group_number);
    246   EXPECT_EQ(trial->group(), winner_index);
    247   EXPECT_EQ(trial->group_name(), winner_name);
    248 }
    249 
    250 TEST_F(FieldTrialTest, DisableProbability) {
    251   const std::string default_group_name = "Default group";
    252   const std::string loser = "Loser";
    253   const std::string name = "Trial";
    254 
    255   // Create a field trail that has expired.
    256   int default_group_number = -1;
    257   FieldTrial* trial = FieldTrialList::FactoryGetFieldTrial(
    258       name, 1000000000, default_group_name, OneYearBeforeBuildTime(), 1, 1,
    259       FieldTrial::SESSION_RANDOMIZED,
    260       &default_group_number);
    261   trial->AppendGroup(loser, 999999999);  // 99.9999999% chance of being chosen.
    262 
    263   // Because trial has expired, we should always be in the default group.
    264   EXPECT_EQ(default_group_number, trial->group());
    265 
    266   // And that default_group_name should ALWAYS win.
    267   EXPECT_EQ(default_group_name, trial->group_name());
    268 }
    269 
    270 TEST_F(FieldTrialTest, ActiveGroups) {
    271   std::string no_group("No Group");
    272   scoped_refptr<FieldTrial> trial =
    273       CreateFieldTrial(no_group, 10, "Default", NULL);
    274 
    275   // There is no winner yet, so no NameGroupId should be returned.
    276   FieldTrial::ActiveGroup active_group;
    277   EXPECT_FALSE(trial->GetActiveGroup(&active_group));
    278 
    279   // Create a single winning group.
    280   std::string one_winner("One Winner");
    281   trial = CreateFieldTrial(one_winner, 10, "Default", NULL);
    282   std::string winner("Winner");
    283   trial->AppendGroup(winner, 10);
    284   EXPECT_FALSE(trial->GetActiveGroup(&active_group));
    285   // Finalize the group selection by accessing the selected group.
    286   trial->group();
    287   EXPECT_TRUE(trial->GetActiveGroup(&active_group));
    288   EXPECT_EQ(one_winner, active_group.trial_name);
    289   EXPECT_EQ(winner, active_group.group_name);
    290 
    291   std::string multi_group("MultiGroup");
    292   scoped_refptr<FieldTrial> multi_group_trial =
    293       CreateFieldTrial(multi_group, 9, "Default", NULL);
    294 
    295   multi_group_trial->AppendGroup("Me", 3);
    296   multi_group_trial->AppendGroup("You", 3);
    297   multi_group_trial->AppendGroup("Them", 3);
    298   EXPECT_FALSE(multi_group_trial->GetActiveGroup(&active_group));
    299   // Finalize the group selection by accessing the selected group.
    300   multi_group_trial->group();
    301   EXPECT_TRUE(multi_group_trial->GetActiveGroup(&active_group));
    302   EXPECT_EQ(multi_group, active_group.trial_name);
    303   EXPECT_EQ(multi_group_trial->group_name(), active_group.group_name);
    304 
    305   // Now check if the list is built properly...
    306   FieldTrial::ActiveGroups active_groups;
    307   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
    308   EXPECT_EQ(2U, active_groups.size());
    309   for (size_t i = 0; i < active_groups.size(); ++i) {
    310     // Order is not guaranteed, so check all values.
    311     EXPECT_NE(no_group, active_groups[i].trial_name);
    312     EXPECT_TRUE(one_winner != active_groups[i].trial_name ||
    313                 winner == active_groups[i].group_name);
    314     EXPECT_TRUE(multi_group != active_groups[i].trial_name ||
    315                 multi_group_trial->group_name() == active_groups[i].group_name);
    316   }
    317 }
    318 
    319 TEST_F(FieldTrialTest, GetActiveFieldTrialGroupsFromString) {
    320   FieldTrial::ActiveGroups active_groups;
    321   FieldTrialList::GetActiveFieldTrialGroupsFromString("*A/X/B/Y/*C/Z",
    322                                                       &active_groups);
    323   ASSERT_EQ(2U, active_groups.size());
    324   EXPECT_EQ("A", active_groups[0].trial_name);
    325   EXPECT_EQ("X", active_groups[0].group_name);
    326   EXPECT_EQ("C", active_groups[1].trial_name);
    327   EXPECT_EQ("Z", active_groups[1].group_name);
    328 }
    329 
    330 TEST_F(FieldTrialTest, AllGroups) {
    331   FieldTrial::State field_trial_state;
    332   std::string one_winner("One Winner");
    333   scoped_refptr<FieldTrial> trial =
    334       CreateFieldTrial(one_winner, 10, "Default", NULL);
    335   std::string winner("Winner");
    336   trial->AppendGroup(winner, 10);
    337   EXPECT_TRUE(trial->GetState(&field_trial_state));
    338   EXPECT_EQ(one_winner, field_trial_state.trial_name);
    339   EXPECT_EQ(winner, field_trial_state.group_name);
    340   trial->group();
    341   EXPECT_TRUE(trial->GetState(&field_trial_state));
    342   EXPECT_EQ(one_winner, field_trial_state.trial_name);
    343   EXPECT_EQ(winner, field_trial_state.group_name);
    344 
    345   std::string multi_group("MultiGroup");
    346   scoped_refptr<FieldTrial> multi_group_trial =
    347       CreateFieldTrial(multi_group, 9, "Default", NULL);
    348 
    349   multi_group_trial->AppendGroup("Me", 3);
    350   multi_group_trial->AppendGroup("You", 3);
    351   multi_group_trial->AppendGroup("Them", 3);
    352   EXPECT_TRUE(multi_group_trial->GetState(&field_trial_state));
    353   // Finalize the group selection by accessing the selected group.
    354   multi_group_trial->group();
    355   EXPECT_TRUE(multi_group_trial->GetState(&field_trial_state));
    356   EXPECT_EQ(multi_group, field_trial_state.trial_name);
    357   EXPECT_EQ(multi_group_trial->group_name(), field_trial_state.group_name);
    358 }
    359 
    360 TEST_F(FieldTrialTest, ActiveGroupsNotFinalized) {
    361   const char kTrialName[] = "TestTrial";
    362   const char kSecondaryGroupName[] = "SecondaryGroup";
    363 
    364   int default_group = -1;
    365   scoped_refptr<FieldTrial> trial =
    366       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, &default_group);
    367   const int secondary_group = trial->AppendGroup(kSecondaryGroupName, 50);
    368 
    369   // Before |group()| is called, |GetActiveGroup()| should return false.
    370   FieldTrial::ActiveGroup active_group;
    371   EXPECT_FALSE(trial->GetActiveGroup(&active_group));
    372 
    373   // |GetActiveFieldTrialGroups()| should also not include the trial.
    374   FieldTrial::ActiveGroups active_groups;
    375   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
    376   EXPECT_TRUE(active_groups.empty());
    377 
    378   // After |group()| has been called, both APIs should succeed.
    379   const int chosen_group = trial->group();
    380   EXPECT_TRUE(chosen_group == default_group || chosen_group == secondary_group);
    381 
    382   EXPECT_TRUE(trial->GetActiveGroup(&active_group));
    383   EXPECT_EQ(kTrialName, active_group.trial_name);
    384   if (chosen_group == default_group)
    385     EXPECT_EQ(kDefaultGroupName, active_group.group_name);
    386   else
    387     EXPECT_EQ(kSecondaryGroupName, active_group.group_name);
    388 
    389   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
    390   ASSERT_EQ(1U, active_groups.size());
    391   EXPECT_EQ(kTrialName, active_groups[0].trial_name);
    392   EXPECT_EQ(active_group.group_name, active_groups[0].group_name);
    393 }
    394 
    395 TEST_F(FieldTrialTest, GetGroupNameWithoutActivation) {
    396   const char kTrialName[] = "TestTrial";
    397   const char kSecondaryGroupName[] = "SecondaryGroup";
    398 
    399   int default_group = -1;
    400   scoped_refptr<FieldTrial> trial =
    401       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, &default_group);
    402   trial->AppendGroup(kSecondaryGroupName, 50);
    403 
    404   // The trial should start inactive.
    405   EXPECT_FALSE(FieldTrialList::IsTrialActive(kTrialName));
    406 
    407   // Calling |GetGroupNameWithoutActivation()| should not activate the trial.
    408   std::string group_name = trial->GetGroupNameWithoutActivation();
    409   EXPECT_FALSE(group_name.empty());
    410   EXPECT_FALSE(FieldTrialList::IsTrialActive(kTrialName));
    411 
    412   // Calling |group_name()| should activate it and return the same group name.
    413   EXPECT_EQ(group_name, trial->group_name());
    414   EXPECT_TRUE(FieldTrialList::IsTrialActive(kTrialName));
    415 }
    416 
    417 TEST_F(FieldTrialTest, Save) {
    418   std::string save_string;
    419 
    420   scoped_refptr<FieldTrial> trial =
    421       CreateFieldTrial("Some name", 10, "Default some name", NULL);
    422   // There is no winner yet, so no textual group name is associated with trial.
    423   // In this case, the trial should not be included.
    424   EXPECT_EQ("", trial->group_name_internal());
    425   FieldTrialList::StatesToString(&save_string);
    426   EXPECT_EQ("", save_string);
    427   save_string.clear();
    428 
    429   // Create a winning group.
    430   trial->AppendGroup("Winner", 10);
    431   // Finalize the group selection by accessing the selected group.
    432   trial->group();
    433   FieldTrialList::StatesToString(&save_string);
    434   EXPECT_EQ("Some name/Winner/", save_string);
    435   save_string.clear();
    436 
    437   // Create a second trial and winning group.
    438   scoped_refptr<FieldTrial> trial2 =
    439       CreateFieldTrial("xxx", 10, "Default xxx", NULL);
    440   trial2->AppendGroup("yyyy", 10);
    441   // Finalize the group selection by accessing the selected group.
    442   trial2->group();
    443 
    444   FieldTrialList::StatesToString(&save_string);
    445   // We assume names are alphabetized... though this is not critical.
    446   EXPECT_EQ("Some name/Winner/xxx/yyyy/", save_string);
    447   save_string.clear();
    448 
    449   // Create a third trial with only the default group.
    450   scoped_refptr<FieldTrial> trial3 =
    451       CreateFieldTrial("zzz", 10, "default", NULL);
    452   // Finalize the group selection by accessing the selected group.
    453   trial3->group();
    454 
    455   FieldTrialList::StatesToString(&save_string);
    456   EXPECT_EQ("Some name/Winner/xxx/yyyy/zzz/default/", save_string);
    457 }
    458 
    459 TEST_F(FieldTrialTest, SaveAll) {
    460   std::string save_string;
    461 
    462   scoped_refptr<FieldTrial> trial =
    463       CreateFieldTrial("Some name", 10, "Default some name", nullptr);
    464   EXPECT_EQ("", trial->group_name_internal());
    465   FieldTrialList::AllStatesToString(&save_string);
    466   EXPECT_EQ("Some name/Default some name/", save_string);
    467   // Getting all states should have finalized the trial.
    468   EXPECT_EQ("Default some name", trial->group_name_internal());
    469   save_string.clear();
    470 
    471   // Create a winning group.
    472   trial = CreateFieldTrial("trial2", 10, "Default some name", nullptr);
    473   trial->AppendGroup("Winner", 10);
    474   // Finalize the group selection by accessing the selected group.
    475   trial->group();
    476   FieldTrialList::AllStatesToString(&save_string);
    477   EXPECT_EQ("Some name/Default some name/*trial2/Winner/", save_string);
    478   save_string.clear();
    479 
    480   // Create a second trial and winning group.
    481   scoped_refptr<FieldTrial> trial2 =
    482       CreateFieldTrial("xxx", 10, "Default xxx", nullptr);
    483   trial2->AppendGroup("yyyy", 10);
    484   // Finalize the group selection by accessing the selected group.
    485   trial2->group();
    486 
    487   FieldTrialList::AllStatesToString(&save_string);
    488   // We assume names are alphabetized... though this is not critical.
    489   EXPECT_EQ("Some name/Default some name/*trial2/Winner/*xxx/yyyy/",
    490             save_string);
    491   save_string.clear();
    492 
    493   // Create a third trial with only the default group.
    494   scoped_refptr<FieldTrial> trial3 =
    495       CreateFieldTrial("zzz", 10, "default", NULL);
    496 
    497   FieldTrialList::AllStatesToString(&save_string);
    498   EXPECT_EQ("Some name/Default some name/*trial2/Winner/*xxx/yyyy/zzz/default/",
    499             save_string);
    500 }
    501 
    502 TEST_F(FieldTrialTest, Restore) {
    503   ASSERT_FALSE(FieldTrialList::TrialExists("Some_name"));
    504   ASSERT_FALSE(FieldTrialList::TrialExists("xxx"));
    505 
    506   FieldTrialList::CreateTrialsFromString("Some_name/Winner/xxx/yyyy/",
    507                                          std::set<std::string>());
    508 
    509   FieldTrial* trial = FieldTrialList::Find("Some_name");
    510   ASSERT_NE(static_cast<FieldTrial*>(NULL), trial);
    511   EXPECT_EQ("Winner", trial->group_name());
    512   EXPECT_EQ("Some_name", trial->trial_name());
    513 
    514   trial = FieldTrialList::Find("xxx");
    515   ASSERT_NE(static_cast<FieldTrial*>(NULL), trial);
    516   EXPECT_EQ("yyyy", trial->group_name());
    517   EXPECT_EQ("xxx", trial->trial_name());
    518 }
    519 
    520 TEST_F(FieldTrialTest, RestoreNotEndingWithSlash) {
    521   EXPECT_TRUE(FieldTrialList::CreateTrialsFromString("tname/gname",
    522                                                      std::set<std::string>()));
    523 
    524   FieldTrial* trial = FieldTrialList::Find("tname");
    525   ASSERT_NE(static_cast<FieldTrial*>(NULL), trial);
    526   EXPECT_EQ("gname", trial->group_name());
    527   EXPECT_EQ("tname", trial->trial_name());
    528 }
    529 
    530 TEST_F(FieldTrialTest, BogusRestore) {
    531   EXPECT_FALSE(FieldTrialList::CreateTrialsFromString("MissingSlash",
    532                                                       std::set<std::string>()));
    533   EXPECT_FALSE(FieldTrialList::CreateTrialsFromString("MissingGroupName/",
    534                                                       std::set<std::string>()));
    535   EXPECT_FALSE(FieldTrialList::CreateTrialsFromString("noname, only group/",
    536                                                       std::set<std::string>()));
    537   EXPECT_FALSE(FieldTrialList::CreateTrialsFromString("/emptyname",
    538                                                       std::set<std::string>()));
    539   EXPECT_FALSE(FieldTrialList::CreateTrialsFromString("*/emptyname",
    540                                                       std::set<std::string>()));
    541 }
    542 
    543 TEST_F(FieldTrialTest, DuplicateRestore) {
    544   scoped_refptr<FieldTrial> trial =
    545       CreateFieldTrial("Some name", 10, "Default", NULL);
    546   trial->AppendGroup("Winner", 10);
    547   // Finalize the group selection by accessing the selected group.
    548   trial->group();
    549   std::string save_string;
    550   FieldTrialList::StatesToString(&save_string);
    551   EXPECT_EQ("Some name/Winner/", save_string);
    552 
    553   // It is OK if we redundantly specify a winner.
    554   EXPECT_TRUE(FieldTrialList::CreateTrialsFromString(save_string,
    555                                                      std::set<std::string>()));
    556 
    557   // But it is an error to try to change to a different winner.
    558   EXPECT_FALSE(FieldTrialList::CreateTrialsFromString("Some name/Loser/",
    559                                                       std::set<std::string>()));
    560 }
    561 
    562 TEST_F(FieldTrialTest, CreateTrialsFromStringNotActive) {
    563   ASSERT_FALSE(FieldTrialList::TrialExists("Abc"));
    564   ASSERT_FALSE(FieldTrialList::TrialExists("Xyz"));
    565   ASSERT_TRUE(FieldTrialList::CreateTrialsFromString("Abc/def/Xyz/zyx/",
    566                                                      std::set<std::string>()));
    567 
    568   FieldTrial::ActiveGroups active_groups;
    569   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
    570   ASSERT_TRUE(active_groups.empty());
    571 
    572   // Check that the values still get returned and querying them activates them.
    573   EXPECT_EQ("def", FieldTrialList::FindFullName("Abc"));
    574   EXPECT_EQ("zyx", FieldTrialList::FindFullName("Xyz"));
    575 
    576   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
    577   ASSERT_EQ(2U, active_groups.size());
    578   EXPECT_EQ("Abc", active_groups[0].trial_name);
    579   EXPECT_EQ("def", active_groups[0].group_name);
    580   EXPECT_EQ("Xyz", active_groups[1].trial_name);
    581   EXPECT_EQ("zyx", active_groups[1].group_name);
    582 }
    583 
    584 TEST_F(FieldTrialTest, CreateTrialsFromStringForceActivation) {
    585   ASSERT_FALSE(FieldTrialList::TrialExists("Abc"));
    586   ASSERT_FALSE(FieldTrialList::TrialExists("def"));
    587   ASSERT_FALSE(FieldTrialList::TrialExists("Xyz"));
    588   ASSERT_TRUE(FieldTrialList::CreateTrialsFromString(
    589       "*Abc/cba/def/fed/*Xyz/zyx/", std::set<std::string>()));
    590 
    591   FieldTrial::ActiveGroups active_groups;
    592   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
    593   ASSERT_EQ(2U, active_groups.size());
    594   EXPECT_EQ("Abc", active_groups[0].trial_name);
    595   EXPECT_EQ("cba", active_groups[0].group_name);
    596   EXPECT_EQ("Xyz", active_groups[1].trial_name);
    597   EXPECT_EQ("zyx", active_groups[1].group_name);
    598 }
    599 
    600 TEST_F(FieldTrialTest, CreateTrialsFromStringNotActiveObserver) {
    601   ASSERT_FALSE(FieldTrialList::TrialExists("Abc"));
    602 
    603   TestFieldTrialObserver observer;
    604   ASSERT_TRUE(FieldTrialList::CreateTrialsFromString("Abc/def/",
    605                                                      std::set<std::string>()));
    606   RunLoop().RunUntilIdle();
    607   // Observer shouldn't be notified.
    608   EXPECT_TRUE(observer.trial_name().empty());
    609 
    610   // Check that the values still get returned and querying them activates them.
    611   EXPECT_EQ("def", FieldTrialList::FindFullName("Abc"));
    612 
    613   RunLoop().RunUntilIdle();
    614   EXPECT_EQ("Abc", observer.trial_name());
    615   EXPECT_EQ("def", observer.group_name());
    616 }
    617 
    618 TEST_F(FieldTrialTest, CreateTrialsFromStringWithIgnoredFieldTrials) {
    619   ASSERT_FALSE(FieldTrialList::TrialExists("Unaccepted1"));
    620   ASSERT_FALSE(FieldTrialList::TrialExists("Foo"));
    621   ASSERT_FALSE(FieldTrialList::TrialExists("Unaccepted2"));
    622   ASSERT_FALSE(FieldTrialList::TrialExists("Bar"));
    623   ASSERT_FALSE(FieldTrialList::TrialExists("Unaccepted3"));
    624 
    625   std::set<std::string> ignored_trial_names;
    626   ignored_trial_names.insert("Unaccepted1");
    627   ignored_trial_names.insert("Unaccepted2");
    628   ignored_trial_names.insert("Unaccepted3");
    629 
    630   FieldTrialList::CreateTrialsFromString(
    631       "Unaccepted1/Unaccepted1_name/"
    632       "Foo/Foo_name/"
    633       "Unaccepted2/Unaccepted2_name/"
    634       "Bar/Bar_name/"
    635       "Unaccepted3/Unaccepted3_name/",
    636       ignored_trial_names);
    637 
    638   EXPECT_FALSE(FieldTrialList::TrialExists("Unaccepted1"));
    639   EXPECT_TRUE(FieldTrialList::TrialExists("Foo"));
    640   EXPECT_FALSE(FieldTrialList::TrialExists("Unaccepted2"));
    641   EXPECT_TRUE(FieldTrialList::TrialExists("Bar"));
    642   EXPECT_FALSE(FieldTrialList::TrialExists("Unaccepted3"));
    643 
    644   FieldTrial::ActiveGroups active_groups;
    645   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
    646   EXPECT_TRUE(active_groups.empty());
    647 
    648   FieldTrial* trial = FieldTrialList::Find("Foo");
    649   ASSERT_NE(static_cast<FieldTrial*>(NULL), trial);
    650   EXPECT_EQ("Foo", trial->trial_name());
    651   EXPECT_EQ("Foo_name", trial->group_name());
    652 
    653   trial = FieldTrialList::Find("Bar");
    654   ASSERT_NE(static_cast<FieldTrial*>(NULL), trial);
    655   EXPECT_EQ("Bar", trial->trial_name());
    656   EXPECT_EQ("Bar_name", trial->group_name());
    657 }
    658 
    659 TEST_F(FieldTrialTest, CreateFieldTrial) {
    660   ASSERT_FALSE(FieldTrialList::TrialExists("Some_name"));
    661 
    662   FieldTrialList::CreateFieldTrial("Some_name", "Winner");
    663 
    664   FieldTrial* trial = FieldTrialList::Find("Some_name");
    665   ASSERT_NE(static_cast<FieldTrial*>(NULL), trial);
    666   EXPECT_EQ("Winner", trial->group_name());
    667   EXPECT_EQ("Some_name", trial->trial_name());
    668 }
    669 
    670 TEST_F(FieldTrialTest, CreateFieldTrialIsNotActive) {
    671   const char kTrialName[] = "CreateFieldTrialIsActiveTrial";
    672   const char kWinnerGroup[] = "Winner";
    673   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
    674   FieldTrialList::CreateFieldTrial(kTrialName, kWinnerGroup);
    675 
    676   FieldTrial::ActiveGroups active_groups;
    677   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
    678   EXPECT_TRUE(active_groups.empty());
    679 }
    680 
    681 TEST_F(FieldTrialTest, DuplicateFieldTrial) {
    682   scoped_refptr<FieldTrial> trial =
    683       CreateFieldTrial("Some_name", 10, "Default", NULL);
    684   trial->AppendGroup("Winner", 10);
    685 
    686   // It is OK if we redundantly specify a winner.
    687   FieldTrial* trial1 = FieldTrialList::CreateFieldTrial("Some_name", "Winner");
    688   EXPECT_TRUE(trial1 != NULL);
    689 
    690   // But it is an error to try to change to a different winner.
    691   FieldTrial* trial2 = FieldTrialList::CreateFieldTrial("Some_name", "Loser");
    692   EXPECT_TRUE(trial2 == NULL);
    693 }
    694 
    695 TEST_F(FieldTrialTest, DisableImmediately) {
    696   int default_group_number = -1;
    697   scoped_refptr<FieldTrial> trial =
    698       CreateFieldTrial("trial", 100, "default", &default_group_number);
    699   trial->Disable();
    700   ASSERT_EQ("default", trial->group_name());
    701   ASSERT_EQ(default_group_number, trial->group());
    702 }
    703 
    704 TEST_F(FieldTrialTest, DisableAfterInitialization) {
    705   scoped_refptr<FieldTrial> trial =
    706       CreateFieldTrial("trial", 100, "default", NULL);
    707   trial->AppendGroup("non_default", 100);
    708   trial->Disable();
    709   ASSERT_EQ("default", trial->group_name());
    710 }
    711 
    712 TEST_F(FieldTrialTest, ForcedFieldTrials) {
    713   // Validate we keep the forced choice.
    714   FieldTrial* forced_trial = FieldTrialList::CreateFieldTrial("Use the",
    715                                                               "Force");
    716   EXPECT_STREQ("Force", forced_trial->group_name().c_str());
    717 
    718   int default_group_number = -1;
    719   scoped_refptr<FieldTrial> factory_trial =
    720       CreateFieldTrial("Use the", 1000, "default", &default_group_number);
    721   EXPECT_EQ(factory_trial.get(), forced_trial);
    722 
    723   int chosen_group = factory_trial->AppendGroup("Force", 100);
    724   EXPECT_EQ(chosen_group, factory_trial->group());
    725   int not_chosen_group = factory_trial->AppendGroup("Dark Side", 100);
    726   EXPECT_NE(chosen_group, not_chosen_group);
    727 
    728   // Since we didn't force the default group, we should not be returned the
    729   // chosen group as the default group.
    730   EXPECT_NE(default_group_number, chosen_group);
    731   int new_group = factory_trial->AppendGroup("Duck Tape", 800);
    732   EXPECT_NE(chosen_group, new_group);
    733   // The new group should not be the default group either.
    734   EXPECT_NE(default_group_number, new_group);
    735 }
    736 
    737 TEST_F(FieldTrialTest, ForcedFieldTrialsDefaultGroup) {
    738   // Forcing the default should use the proper group ID.
    739   FieldTrial* forced_trial = FieldTrialList::CreateFieldTrial("Trial Name",
    740                                                               "Default");
    741   int default_group_number = -1;
    742   scoped_refptr<FieldTrial> factory_trial =
    743       CreateFieldTrial("Trial Name", 1000, "Default", &default_group_number);
    744   EXPECT_EQ(forced_trial, factory_trial.get());
    745 
    746   int other_group = factory_trial->AppendGroup("Not Default", 100);
    747   EXPECT_STREQ("Default", factory_trial->group_name().c_str());
    748   EXPECT_EQ(default_group_number, factory_trial->group());
    749   EXPECT_NE(other_group, factory_trial->group());
    750 
    751   int new_other_group = factory_trial->AppendGroup("Not Default Either", 800);
    752   EXPECT_NE(new_other_group, factory_trial->group());
    753 }
    754 
    755 TEST_F(FieldTrialTest, SetForced) {
    756   // Start by setting a trial for which we ensure a winner...
    757   int default_group_number = -1;
    758   scoped_refptr<FieldTrial> forced_trial =
    759       CreateFieldTrial("Use the", 1, "default", &default_group_number);
    760   EXPECT_EQ(forced_trial, forced_trial);
    761 
    762   int forced_group = forced_trial->AppendGroup("Force", 1);
    763   EXPECT_EQ(forced_group, forced_trial->group());
    764 
    765   // Now force it.
    766   forced_trial->SetForced();
    767 
    768   // Now try to set it up differently as a hard coded registration would.
    769   scoped_refptr<FieldTrial> hard_coded_trial =
    770       CreateFieldTrial("Use the", 1, "default", &default_group_number);
    771   EXPECT_EQ(hard_coded_trial, forced_trial);
    772 
    773   int would_lose_group = hard_coded_trial->AppendGroup("Force", 0);
    774   EXPECT_EQ(forced_group, hard_coded_trial->group());
    775   EXPECT_EQ(forced_group, would_lose_group);
    776 
    777   // Same thing if we would have done it to win again.
    778   scoped_refptr<FieldTrial> other_hard_coded_trial =
    779       CreateFieldTrial("Use the", 1, "default", &default_group_number);
    780   EXPECT_EQ(other_hard_coded_trial, forced_trial);
    781 
    782   int would_win_group = other_hard_coded_trial->AppendGroup("Force", 1);
    783   EXPECT_EQ(forced_group, other_hard_coded_trial->group());
    784   EXPECT_EQ(forced_group, would_win_group);
    785 }
    786 
    787 TEST_F(FieldTrialTest, SetForcedDefaultOnly) {
    788   const char kTrialName[] = "SetForcedDefaultOnly";
    789   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
    790 
    791   int default_group = -1;
    792   scoped_refptr<FieldTrial> trial =
    793       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, &default_group);
    794   trial->SetForced();
    795 
    796   trial = CreateFieldTrial(kTrialName, 100, kDefaultGroupName, NULL);
    797   EXPECT_EQ(default_group, trial->group());
    798   EXPECT_EQ(kDefaultGroupName, trial->group_name());
    799 }
    800 
    801 TEST_F(FieldTrialTest, SetForcedDefaultWithExtraGroup) {
    802   const char kTrialName[] = "SetForcedDefaultWithExtraGroup";
    803   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
    804 
    805   int default_group = -1;
    806   scoped_refptr<FieldTrial> trial =
    807       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, &default_group);
    808   trial->SetForced();
    809 
    810   trial = CreateFieldTrial(kTrialName, 100, kDefaultGroupName, NULL);
    811   const int extra_group = trial->AppendGroup("Extra", 100);
    812   EXPECT_EQ(default_group, trial->group());
    813   EXPECT_NE(extra_group, trial->group());
    814   EXPECT_EQ(kDefaultGroupName, trial->group_name());
    815 }
    816 
    817 TEST_F(FieldTrialTest, SetForcedTurnFeatureOn) {
    818   const char kTrialName[] = "SetForcedTurnFeatureOn";
    819   const char kExtraGroupName[] = "Extra";
    820   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
    821 
    822   // Simulate a server-side (forced) config that turns the feature on when the
    823   // original hard-coded config had it disabled.
    824   scoped_refptr<FieldTrial> forced_trial =
    825       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, NULL);
    826   forced_trial->AppendGroup(kExtraGroupName, 100);
    827   forced_trial->SetForced();
    828 
    829   int default_group = -1;
    830   scoped_refptr<FieldTrial> client_trial =
    831       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, &default_group);
    832   const int extra_group = client_trial->AppendGroup(kExtraGroupName, 0);
    833   EXPECT_NE(default_group, extra_group);
    834 
    835   EXPECT_FALSE(client_trial->group_reported_);
    836   EXPECT_EQ(extra_group, client_trial->group());
    837   EXPECT_TRUE(client_trial->group_reported_);
    838   EXPECT_EQ(kExtraGroupName, client_trial->group_name());
    839 }
    840 
    841 TEST_F(FieldTrialTest, SetForcedTurnFeatureOff) {
    842   const char kTrialName[] = "SetForcedTurnFeatureOff";
    843   const char kExtraGroupName[] = "Extra";
    844   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
    845 
    846   // Simulate a server-side (forced) config that turns the feature off when the
    847   // original hard-coded config had it enabled.
    848   scoped_refptr<FieldTrial> forced_trial =
    849       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, NULL);
    850   forced_trial->AppendGroup(kExtraGroupName, 0);
    851   forced_trial->SetForced();
    852 
    853   int default_group = -1;
    854   scoped_refptr<FieldTrial> client_trial =
    855       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, &default_group);
    856   const int extra_group = client_trial->AppendGroup(kExtraGroupName, 100);
    857   EXPECT_NE(default_group, extra_group);
    858 
    859   EXPECT_FALSE(client_trial->group_reported_);
    860   EXPECT_EQ(default_group, client_trial->group());
    861   EXPECT_TRUE(client_trial->group_reported_);
    862   EXPECT_EQ(kDefaultGroupName, client_trial->group_name());
    863 }
    864 
    865 TEST_F(FieldTrialTest, SetForcedChangeDefault_Default) {
    866   const char kTrialName[] = "SetForcedDefaultGroupChange";
    867   const char kGroupAName[] = "A";
    868   const char kGroupBName[] = "B";
    869   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
    870 
    871   // Simulate a server-side (forced) config that switches which group is default
    872   // and ensures that the non-forced code receives the correct group numbers.
    873   scoped_refptr<FieldTrial> forced_trial =
    874       CreateFieldTrial(kTrialName, 100, kGroupAName, NULL);
    875   forced_trial->AppendGroup(kGroupBName, 100);
    876   forced_trial->SetForced();
    877 
    878   int default_group = -1;
    879   scoped_refptr<FieldTrial> client_trial =
    880       CreateFieldTrial(kTrialName, 100, kGroupBName, &default_group);
    881   const int extra_group = client_trial->AppendGroup(kGroupAName, 50);
    882   EXPECT_NE(default_group, extra_group);
    883 
    884   EXPECT_FALSE(client_trial->group_reported_);
    885   EXPECT_EQ(default_group, client_trial->group());
    886   EXPECT_TRUE(client_trial->group_reported_);
    887   EXPECT_EQ(kGroupBName, client_trial->group_name());
    888 }
    889 
    890 TEST_F(FieldTrialTest, SetForcedChangeDefault_NonDefault) {
    891   const char kTrialName[] = "SetForcedDefaultGroupChange";
    892   const char kGroupAName[] = "A";
    893   const char kGroupBName[] = "B";
    894   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
    895 
    896   // Simulate a server-side (forced) config that switches which group is default
    897   // and ensures that the non-forced code receives the correct group numbers.
    898   scoped_refptr<FieldTrial> forced_trial =
    899       CreateFieldTrial(kTrialName, 100, kGroupAName, NULL);
    900   forced_trial->AppendGroup(kGroupBName, 0);
    901   forced_trial->SetForced();
    902 
    903   int default_group = -1;
    904   scoped_refptr<FieldTrial> client_trial =
    905       CreateFieldTrial(kTrialName, 100, kGroupBName, &default_group);
    906   const int extra_group = client_trial->AppendGroup(kGroupAName, 50);
    907   EXPECT_NE(default_group, extra_group);
    908 
    909   EXPECT_FALSE(client_trial->group_reported_);
    910   EXPECT_EQ(extra_group, client_trial->group());
    911   EXPECT_TRUE(client_trial->group_reported_);
    912   EXPECT_EQ(kGroupAName, client_trial->group_name());
    913 }
    914 
    915 TEST_F(FieldTrialTest, Observe) {
    916   const char kTrialName[] = "TrialToObserve1";
    917   const char kSecondaryGroupName[] = "SecondaryGroup";
    918 
    919   TestFieldTrialObserver observer;
    920   int default_group = -1;
    921   scoped_refptr<FieldTrial> trial =
    922       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, &default_group);
    923   const int secondary_group = trial->AppendGroup(kSecondaryGroupName, 50);
    924   const int chosen_group = trial->group();
    925   EXPECT_TRUE(chosen_group == default_group || chosen_group == secondary_group);
    926 
    927   RunLoop().RunUntilIdle();
    928   EXPECT_EQ(kTrialName, observer.trial_name());
    929   if (chosen_group == default_group)
    930     EXPECT_EQ(kDefaultGroupName, observer.group_name());
    931   else
    932     EXPECT_EQ(kSecondaryGroupName, observer.group_name());
    933 }
    934 
    935 TEST_F(FieldTrialTest, ObserveDisabled) {
    936   const char kTrialName[] = "TrialToObserve2";
    937 
    938   TestFieldTrialObserver observer;
    939   int default_group = -1;
    940   scoped_refptr<FieldTrial> trial =
    941       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, &default_group);
    942   trial->AppendGroup("A", 25);
    943   trial->AppendGroup("B", 25);
    944   trial->AppendGroup("C", 25);
    945   trial->Disable();
    946 
    947   // Observer shouldn't be notified of a disabled trial.
    948   RunLoop().RunUntilIdle();
    949   EXPECT_TRUE(observer.trial_name().empty());
    950   EXPECT_TRUE(observer.group_name().empty());
    951 
    952   // Observer shouldn't be notified even after a |group()| call.
    953   EXPECT_EQ(default_group, trial->group());
    954   RunLoop().RunUntilIdle();
    955   EXPECT_TRUE(observer.trial_name().empty());
    956   EXPECT_TRUE(observer.group_name().empty());
    957 }
    958 
    959 TEST_F(FieldTrialTest, ObserveForcedDisabled) {
    960   const char kTrialName[] = "TrialToObserve3";
    961 
    962   TestFieldTrialObserver observer;
    963   int default_group = -1;
    964   scoped_refptr<FieldTrial> trial =
    965       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, &default_group);
    966   trial->AppendGroup("A", 25);
    967   trial->AppendGroup("B", 25);
    968   trial->AppendGroup("C", 25);
    969   trial->SetForced();
    970   trial->Disable();
    971 
    972   // Observer shouldn't be notified of a disabled trial, even when forced.
    973   RunLoop().RunUntilIdle();
    974   EXPECT_TRUE(observer.trial_name().empty());
    975   EXPECT_TRUE(observer.group_name().empty());
    976 
    977   // Observer shouldn't be notified even after a |group()| call.
    978   EXPECT_EQ(default_group, trial->group());
    979   RunLoop().RunUntilIdle();
    980   EXPECT_TRUE(observer.trial_name().empty());
    981   EXPECT_TRUE(observer.group_name().empty());
    982 }
    983 
    984 TEST_F(FieldTrialTest, DisabledTrialNotActive) {
    985   const char kTrialName[] = "DisabledTrial";
    986   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
    987 
    988   scoped_refptr<FieldTrial> trial =
    989       CreateFieldTrial(kTrialName, 100, kDefaultGroupName, NULL);
    990   trial->AppendGroup("X", 50);
    991   trial->Disable();
    992 
    993   // Ensure the trial is not listed as active.
    994   FieldTrial::ActiveGroups active_groups;
    995   FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
    996   EXPECT_TRUE(active_groups.empty());
    997 
    998   // Ensure the trial is not listed in the |StatesToString()| result.
    999   std::string states;
   1000   FieldTrialList::StatesToString(&states);
   1001   EXPECT_TRUE(states.empty());
   1002 }
   1003 
   1004 TEST_F(FieldTrialTest, ExpirationYearNotExpired) {
   1005   const char kTrialName[] = "NotExpired";
   1006   const char kGroupName[] = "Group2";
   1007   const int kProbability = 100;
   1008   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
   1009 
   1010   scoped_refptr<FieldTrial> trial =
   1011       CreateFieldTrial(kTrialName, kProbability, kDefaultGroupName, NULL);
   1012   trial->AppendGroup(kGroupName, kProbability);
   1013   EXPECT_EQ(kGroupName, trial->group_name());
   1014 }
   1015 
   1016 TEST_F(FieldTrialTest, FloatBoundariesGiveEqualGroupSizes) {
   1017   const int kBucketCount = 100;
   1018 
   1019   // Try each boundary value |i / 100.0| as the entropy value.
   1020   for (int i = 0; i < kBucketCount; ++i) {
   1021     const double entropy = i / static_cast<double>(kBucketCount);
   1022 
   1023     scoped_refptr<base::FieldTrial> trial(
   1024         new base::FieldTrial("test", kBucketCount, "default", entropy));
   1025     for (int j = 0; j < kBucketCount; ++j)
   1026       trial->AppendGroup(base::IntToString(j), 1);
   1027 
   1028     EXPECT_EQ(base::IntToString(i), trial->group_name());
   1029   }
   1030 }
   1031 
   1032 TEST_F(FieldTrialTest, DoesNotSurpassTotalProbability) {
   1033   const double kEntropyValue = 1.0 - 1e-9;
   1034   ASSERT_LT(kEntropyValue, 1.0);
   1035 
   1036   scoped_refptr<base::FieldTrial> trial(
   1037       new base::FieldTrial("test", 2, "default", kEntropyValue));
   1038   trial->AppendGroup("1", 1);
   1039   trial->AppendGroup("2", 1);
   1040 
   1041   EXPECT_EQ("2", trial->group_name());
   1042 }
   1043 
   1044 TEST_F(FieldTrialTest, CreateSimulatedFieldTrial) {
   1045   const char kTrialName[] = "CreateSimulatedFieldTrial";
   1046   ASSERT_FALSE(FieldTrialList::TrialExists(kTrialName));
   1047 
   1048   // Different cases to test, e.g. default vs. non default group being chosen.
   1049   struct {
   1050     double entropy_value;
   1051     const char* expected_group;
   1052   } test_cases[] = {
   1053     { 0.4, "A" },
   1054     { 0.85, "B" },
   1055     { 0.95, kDefaultGroupName },
   1056   };
   1057 
   1058   for (size_t i = 0; i < arraysize(test_cases); ++i) {
   1059     TestFieldTrialObserver observer;
   1060     scoped_refptr<FieldTrial> trial(
   1061        FieldTrial::CreateSimulatedFieldTrial(kTrialName, 100, kDefaultGroupName,
   1062                                              test_cases[i].entropy_value));
   1063     trial->AppendGroup("A", 80);
   1064     trial->AppendGroup("B", 10);
   1065     EXPECT_EQ(test_cases[i].expected_group, trial->group_name());
   1066 
   1067     // Field trial shouldn't have been registered with the list.
   1068     EXPECT_FALSE(FieldTrialList::TrialExists(kTrialName));
   1069     EXPECT_EQ(0u, FieldTrialList::GetFieldTrialCount());
   1070 
   1071     // Observer shouldn't have been notified.
   1072     RunLoop().RunUntilIdle();
   1073     EXPECT_TRUE(observer.trial_name().empty());
   1074 
   1075     // The trial shouldn't be in the active set of trials.
   1076     FieldTrial::ActiveGroups active_groups;
   1077     FieldTrialList::GetActiveFieldTrialGroups(&active_groups);
   1078     EXPECT_TRUE(active_groups.empty());
   1079 
   1080     // The trial shouldn't be listed in the |StatesToString()| result.
   1081     std::string states;
   1082     FieldTrialList::StatesToString(&states);
   1083     EXPECT_TRUE(states.empty());
   1084   }
   1085 }
   1086 
   1087 TEST(FieldTrialTestWithoutList, StatesStringFormat) {
   1088   std::string save_string;
   1089 
   1090   // Scoping the first FieldTrialList, as we need another one to test the
   1091   // importing function.
   1092   {
   1093     FieldTrialList field_trial_list(NULL);
   1094     scoped_refptr<FieldTrial> trial =
   1095         CreateFieldTrial("Abc", 10, "Default some name", NULL);
   1096     trial->AppendGroup("cba", 10);
   1097     trial->group();
   1098     scoped_refptr<FieldTrial> trial2 =
   1099         CreateFieldTrial("Xyz", 10, "Default xxx", NULL);
   1100     trial2->AppendGroup("zyx", 10);
   1101     trial2->group();
   1102     scoped_refptr<FieldTrial> trial3 =
   1103         CreateFieldTrial("zzz", 10, "default", NULL);
   1104 
   1105     FieldTrialList::AllStatesToString(&save_string);
   1106   }
   1107 
   1108   // Starting with a new blank FieldTrialList.
   1109   FieldTrialList field_trial_list(NULL);
   1110   ASSERT_TRUE(field_trial_list.CreateTrialsFromString(save_string,
   1111                                                       std::set<std::string>()));
   1112 
   1113   FieldTrial::ActiveGroups active_groups;
   1114   field_trial_list.GetActiveFieldTrialGroups(&active_groups);
   1115   ASSERT_EQ(2U, active_groups.size());
   1116   EXPECT_EQ("Abc", active_groups[0].trial_name);
   1117   EXPECT_EQ("cba", active_groups[0].group_name);
   1118   EXPECT_EQ("Xyz", active_groups[1].trial_name);
   1119   EXPECT_EQ("zyx", active_groups[1].group_name);
   1120   EXPECT_TRUE(field_trial_list.TrialExists("zzz"));
   1121 }
   1122 
   1123 #if GTEST_HAS_DEATH_TEST
   1124 TEST(FieldTrialDeathTest, OneTimeRandomizedTrialWithoutFieldTrialList) {
   1125   // Trying to instantiate a one-time randomized field trial before the
   1126   // FieldTrialList is created should crash.
   1127   EXPECT_DEATH(FieldTrialList::FactoryGetFieldTrial(
   1128       "OneTimeRandomizedTrialWithoutFieldTrialList", 100, kDefaultGroupName,
   1129       base::FieldTrialList::kNoExpirationYear, 1, 1,
   1130       base::FieldTrial::ONE_TIME_RANDOMIZED, NULL), "");
   1131 }
   1132 #endif
   1133 
   1134 }  // namespace base
   1135