Supporting command line argument to force field trials

base/metrics/field_trial_unittest.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 // Test of FieldTrial class
 
 #include "base/metrics/field_trial.h"
 
 #include "base/rand_util.h"
 #include "base/stringprintf.h"
@@ skipping 29 matching lines @@
 };
 
 // Test registration, and also check that destructors are called for trials
 // (and that Valgrind doesn't catch us leaking).
 TEST_F(FieldTrialTest, Registration) {
   const char* name1 = "name 1 test";
   const char* name2 = "name 2 test";
   EXPECT_FALSE(FieldTrialList::Find(name1));
   EXPECT_FALSE(FieldTrialList::Find(name2));
 
-  FieldTrial* trial1 =
-      new FieldTrial(name1, 10, "default name 1 test", next_year_, 12, 31);
+  FieldTrial* trial1 = FieldTrialList::FactoryGetFieldTrial(
+      name1, 10, "default name 1 test", next_year_, 12, 31, NULL);
   EXPECT_EQ(FieldTrial::kNotFinalized, trial1->group_);
   EXPECT_EQ(name1, trial1->name());
   EXPECT_EQ("", trial1->group_name_internal());
 
   trial1->AppendGroup("", 7);
 
   EXPECT_EQ(trial1, FieldTrialList::Find(name1));
   EXPECT_FALSE(FieldTrialList::Find(name2));
 
-  FieldTrial* trial2 =
-      new FieldTrial(name2, 10, "default name 2 test", next_year_, 12, 31);
+  FieldTrial* trial2 = FieldTrialList::FactoryGetFieldTrial(
+      name2, 10, "default name 2 test", next_year_, 12, 31, NULL);
   EXPECT_EQ(FieldTrial::kNotFinalized, trial2->group_);
   EXPECT_EQ(name2, trial2->name());
   EXPECT_EQ("", trial2->group_name_internal());
 
   trial2->AppendGroup("a first group", 7);
 
   EXPECT_EQ(trial1, FieldTrialList::Find(name1));
   EXPECT_EQ(trial2, FieldTrialList::Find(name2));
   // Note: FieldTrialList should delete the objects at shutdown.
 }
 
 TEST_F(FieldTrialTest, AbsoluteProbabilities) {
   char always_true[] = " always true";
   char default_always_true[] = " default always true";
   char always_false[] = " always false";
   char default_always_false[] = " default always false";
   for (int i = 1; i < 250; ++i) {
     // Try lots of names, by changing the first character of the name.
     always_true[0] = i;
     default_always_true[0] = i;
     always_false[0] = i;
     default_always_false[0] = i;
 
-    FieldTrial* trial_true =
-        new FieldTrial(
-            always_true, 10, default_always_true, next_year_, 12, 31);
+    FieldTrial* trial_true = FieldTrialList::FactoryGetFieldTrial(
+        always_true, 10, default_always_true, next_year_, 12, 31, NULL);
     const std::string winner = "TheWinner";
     int winner_group = trial_true->AppendGroup(winner, 10);
 
     EXPECT_EQ(winner_group, trial_true->group());
     EXPECT_EQ(winner, trial_true->group_name());
 
-    FieldTrial* trial_false =
-        new FieldTrial(
-            always_false, 10, default_always_false, next_year_, 12, 31);
+    FieldTrial* trial_false = FieldTrialList::FactoryGetFieldTrial(
+        always_false, 10, default_always_false, next_year_, 12, 31, NULL);
     int loser_group = trial_false->AppendGroup("ALoser", 0);
 
     EXPECT_NE(loser_group, trial_false->group());
   }
 }
 
 TEST_F(FieldTrialTest, RemainingProbability) {
   // First create a test that hasn't had a winner yet.
   const std::string winner = "Winner";
   const std::string loser = "Loser";
   scoped_refptr<FieldTrial> trial;
   int counter = 0;
+  int default_group_number = -1;
   do {
     std::string name = StringPrintf("trial%d", ++counter);
-    trial = new FieldTrial(name, 10, winner, next_year_, 12, 31);
+    trial = FieldTrialList::FactoryGetFieldTrial(
+        name, 10, winner, next_year_, 12, 31, &default_group_number);
     trial->AppendGroup(loser, 5);  // 50% chance of not being chosen.
     // If a group is not assigned, group_ will be kNotFinalized.
   } while (trial->group_ != FieldTrial::kNotFinalized);
 
   // And that 'default' group (winner) should always win.
-  EXPECT_EQ(FieldTrial::kDefaultGroupNumber, trial->group());
+  EXPECT_EQ(default_group_number, trial->group());
 
   // And that winner should ALWAYS win.
   EXPECT_EQ(winner, trial->group_name());
 }
 
 TEST_F(FieldTrialTest, FiftyFiftyProbability) {
   // Check that even with small divisors, we have the proper probabilities, and
   // all outcomes are possible.  Since this is a 50-50 test, it should get both
   // outcomes in a few tries, but we'll try no more than 100 times (and be flaky
   // with probability around 1 in 2^99).
   bool first_winner = false;
   bool second_winner = false;
   int counter = 0;
   do {
     std::string name = base::StringPrintf("FiftyFifty%d", ++counter);
     std::string default_group_name = base::StringPrintf("Default FiftyFifty%d",
                                                         ++counter);
-    scoped_refptr<FieldTrial> trial(
-        new FieldTrial(name, 2, default_group_name, next_year_, 12, 31));
+    scoped_refptr<FieldTrial> trial(FieldTrialList::FactoryGetFieldTrial(
+        name, 2, default_group_name, next_year_, 12, 31, NULL));
     trial->AppendGroup("first", 1);  // 50% chance of being chosen.
     // If group_ is kNotFinalized, then a group assignement hasn't been done.
     if (trial->group_ != FieldTrial::kNotFinalized) {
       first_winner = true;
       continue;
     }
     trial->AppendGroup("second", 1);  // Always chosen at this point.
     EXPECT_NE(FieldTrial::kNotFinalized, trial->group());
     second_winner = true;
   } while ((!second_winner || !first_winner) && counter < 100);
   EXPECT_TRUE(second_winner);
   EXPECT_TRUE(first_winner);
 }
 
 TEST_F(FieldTrialTest, MiddleProbabilities) {
   char name[] = " same name";
   char default_group_name[] = " default same name";
   bool false_event_seen = false;
   bool true_event_seen = false;
   for (int i = 1; i < 250; ++i) {
     name[0] = i;
     default_group_name[0] = i;
-    FieldTrial* trial =
-        new FieldTrial(name, 10, default_group_name, next_year_, 12, 31);
+    FieldTrial* trial = FieldTrialList::FactoryGetFieldTrial(
+        name, 10, default_group_name, next_year_, 12, 31, NULL);
     int might_win = trial->AppendGroup("MightWin", 5);
 
     if (trial->group() == might_win) {
       true_event_seen = true;
     } else {
       false_event_seen = true;
     }
     if (false_event_seen && true_event_seen)
       return;  // Successful test!!!
   }
   // Very surprising to get here. Probability should be around 1 in 2 ** 250.
   // One of the following will fail.
   EXPECT_TRUE(false_event_seen);
   EXPECT_TRUE(true_event_seen);
 }
 
 TEST_F(FieldTrialTest, OneWinner) {
   char name[] = "Some name";
   char default_group_name[] = "Default some name";
   int group_count(10);
 
-  FieldTrial* trial =
-      new FieldTrial(
-          name, group_count, default_group_name, next_year_, 12, 31);
+  int default_group_number = -1;
+  FieldTrial* trial = FieldTrialList::FactoryGetFieldTrial(
+      name, group_count, default_group_name, next_year_, 12, 31,
+      &default_group_number);
   int winner_index(-2);
   std::string winner_name;
 
   for (int i = 1; i <= group_count; ++i) {
     int might_win = trial->AppendGroup("", 1);
 
     // Because we keep appending groups, we want to see if the last group that
     // was added has been assigned or not.
     if (trial->group_ == might_win) {
       EXPECT_EQ(-2, winner_index);
       winner_index = might_win;
       StringAppendF(&winner_name, "%d", might_win);
       EXPECT_EQ(winner_name, trial->group_name());
     }
   }
   EXPECT_GE(winner_index, 0);
+  // Since all groups cover the total probability, we should not have
+  // chosen the default group.
+  EXPECT_NE(trial->group(), default_group_number);
   EXPECT_EQ(trial->group(), winner_index);
   EXPECT_EQ(trial->group_name(), winner_name);
 }
 
 TEST_F(FieldTrialTest, DisableProbability) {
   const std::string default_group_name = "Default group";
   const std::string loser = "Loser";
   const std::string name = "Trial";
 
   // Create a field trail that has expired.
+  int default_group_number = -1;
   scoped_refptr<FieldTrial> trial;
-  trial = new FieldTrial(
-      name, 1000000000, default_group_name, last_year_, 1, 1);
+  trial = FieldTrialList::FactoryGetFieldTrial(
+      name, 1000000000, default_group_name, last_year_, 1, 1,
+      &default_group_number);
   trial->AppendGroup(loser, 999999999);  // 99.9999999% chance of being chosen.
 
   // Because trial has expired, we should always be in the default group.
-  EXPECT_EQ(FieldTrial::kDefaultGroupNumber, trial->group());
+  EXPECT_EQ(default_group_number, trial->group());
 
   // And that default_group_name should ALWAYS win.
   EXPECT_EQ(default_group_name, trial->group_name());
 }
 
 TEST_F(FieldTrialTest, HashName) {
   // Make sure hashing is stable on all platforms.
   struct {
     const char* name;
     uint32 hash_value;
   } known_hashes[] = {
     {"a", 937752454u},
     {"1", 723085877u},
     {"Trial Name", 2713117220u},
     {"Group Name", 3201815843u},
     {"My Favorite Experiment", 3722155194u},
     {"My Awesome Group Name", 4109503236u},
     {"abcdefghijklmonpqrstuvwxyz", 787728696u},
     {"0123456789ABCDEF", 348858318U}
   };
   for (size_t i = 0; i < ARRAYSIZE_UNSAFE(known_hashes); ++i) {
     EXPECT_EQ(known_hashes[i].hash_value,
               FieldTrial::HashName(known_hashes[i].name));
   }
 }
 
 TEST_F(FieldTrialTest, NameGroupIds) {
   std::string no_group("No Group");
   uint32 no_group_id = FieldTrial::HashName(no_group);
-  scoped_refptr<FieldTrial> trial(new FieldTrial(
-      no_group, 10, "Default", next_year_, 12, 31));
+  scoped_refptr<FieldTrial> trial(FieldTrialList::FactoryGetFieldTrial(
+      no_group, 10, "Default", next_year_, 12, 31, NULL));
 
   // There is no winner yet, so no NameGroupId should be returned.
   FieldTrial::NameGroupId name_group_id;
   EXPECT_FALSE(trial->GetNameGroupId(&name_group_id));
 
   // Create a single winning group.
   std::string one_winner("One Winner");
   uint32 one_winner_id = FieldTrial::HashName(one_winner);
-  trial = new FieldTrial(one_winner, 10, "Default", next_year_, 12, 31);
+  trial = FieldTrialList::FactoryGetFieldTrial(
+      one_winner, 10, "Default", next_year_, 12, 31, NULL);
   std::string winner("Winner");
   uint32 winner_group_id = FieldTrial::HashName(winner);
   trial->AppendGroup(winner, 10);
   EXPECT_TRUE(trial->GetNameGroupId(&name_group_id));
   EXPECT_EQ(one_winner_id, name_group_id.name);
   EXPECT_EQ(winner_group_id, name_group_id.group);
 
   std::string multi_group("MultiGroup");
   uint32 multi_group_id = FieldTrial::HashName(multi_group);
   scoped_refptr<FieldTrial> multi_group_trial =
-      new FieldTrial(multi_group, 9, "Default", next_year_, 12, 31);
+      FieldTrialList::FactoryGetFieldTrial(multi_group, 9, "Default",
+                                            next_year_, 12, 31, NULL);
 
   multi_group_trial->AppendGroup("Me", 3);
   multi_group_trial->AppendGroup("You", 3);
   multi_group_trial->AppendGroup("Them", 3);
   EXPECT_TRUE(multi_group_trial->GetNameGroupId(&name_group_id));
   EXPECT_EQ(multi_group_id, name_group_id.name);
   uint32 multi_group_winner_id =
       FieldTrial::HashName(multi_group_trial->group_name());
   EXPECT_EQ(multi_group_winner_id, name_group_id.group);
 
   // Now check if the list is built properly...
   std::vector<FieldTrial::NameGroupId> name_group_ids;
   FieldTrialList::GetFieldTrialNameGroupIds(&name_group_ids);
   EXPECT_EQ(2U, name_group_ids.size());
   for (size_t i = 0; i < name_group_ids.size(); ++i) {
     // Order is not guaranteed, so check all values.
     EXPECT_NE(no_group_id, name_group_ids[i].name);
     EXPECT_TRUE(one_winner_id != name_group_ids[i].name ||
                 winner_group_id == name_group_ids[i].group);
     EXPECT_TRUE(multi_group_id != name_group_ids[i].name ||
                 multi_group_winner_id == name_group_ids[i].group);
   }
 }
 
 TEST_F(FieldTrialTest, Save) {
   std::string save_string;
 
-  FieldTrial* trial =
-      new FieldTrial(
-          "Some name", 10, "Default some name", next_year_, 12, 31);
+  FieldTrial* trial = FieldTrialList::FactoryGetFieldTrial(
+      "Some name", 10, "Default some name", next_year_, 12, 31, NULL);
   // There is no winner yet, so no textual group name is associated with trial.
   // In this case, the trial should not be included.
   EXPECT_EQ("", trial->group_name_internal());
   FieldTrialList::StatesToString(&save_string);
   EXPECT_EQ("", save_string);
   save_string.clear();
 
   // Create a winning group.
   trial->AppendGroup("Winner", 10);
   FieldTrialList::StatesToString(&save_string);
   EXPECT_EQ("Some name/Winner/", save_string);
   save_string.clear();
 
   // Create a second trial and winning group.
-  FieldTrial* trial2 =
-      new FieldTrial("xxx", 10, "Default xxx", next_year_, 12, 31);
+  FieldTrial* trial2 = FieldTrialList::FactoryGetFieldTrial(
+      "xxx", 10, "Default xxx", next_year_, 12, 31, NULL);
   trial2->AppendGroup("yyyy", 10);
 
   FieldTrialList::StatesToString(&save_string);
   // We assume names are alphabetized... though this is not critical.
   EXPECT_EQ("Some name/Winner/xxx/yyyy/", save_string);
 }
 
 TEST_F(FieldTrialTest, Restore) {
   EXPECT_TRUE(FieldTrialList::Find("Some_name") == NULL);
   EXPECT_TRUE(FieldTrialList::Find("xxx") == NULL);
 
-  FieldTrialList::CreateTrialsInChildProcess("Some_name/Winner/xxx/yyyy/");
+  FieldTrialList::CreateTrialsFromString("Some_name/Winner/xxx/yyyy/");
 
   FieldTrial* trial = FieldTrialList::Find("Some_name");
   ASSERT_NE(static_cast<FieldTrial*>(NULL), trial);
   EXPECT_EQ("Winner", trial->group_name());
   EXPECT_EQ("Some_name", trial->name());
 
   trial = FieldTrialList::Find("xxx");
   ASSERT_NE(static_cast<FieldTrial*>(NULL), trial);
   EXPECT_EQ("yyyy", trial->group_name());
   EXPECT_EQ("xxx", trial->name());
 }
 
 TEST_F(FieldTrialTest, BogusRestore) {
-  EXPECT_FALSE(FieldTrialList::CreateTrialsInChildProcess("MissingSlash"));
-  EXPECT_FALSE(FieldTrialList::CreateTrialsInChildProcess("MissingGroupName/"));
-  EXPECT_FALSE(FieldTrialList::CreateTrialsInChildProcess(
+  EXPECT_FALSE(FieldTrialList::CreateTrialsFromString("MissingSlash"));
+  EXPECT_FALSE(FieldTrialList::CreateTrialsFromString("MissingGroupName/"));
+  EXPECT_FALSE(FieldTrialList::CreateTrialsFromString(
       "MissingFinalSlash/gname"));
-  EXPECT_FALSE(FieldTrialList::CreateTrialsInChildProcess(
+  EXPECT_FALSE(FieldTrialList::CreateTrialsFromString(
       "noname, only group/"));
 }
 
 TEST_F(FieldTrialTest, DuplicateRestore) {
-  FieldTrial* trial =
-      new FieldTrial(
-          "Some name", 10, "Default some name", next_year_, 12, 31);
+  FieldTrial* trial = FieldTrialList::FactoryGetFieldTrial(
+      "Some name", 10, "Default some name", next_year_, 12, 31, NULL);
   trial->AppendGroup("Winner", 10);
   std::string save_string;
   FieldTrialList::StatesToString(&save_string);
   EXPECT_EQ("Some name/Winner/", save_string);
 
   // It is OK if we redundantly specify a winner.
-  EXPECT_TRUE(FieldTrialList::CreateTrialsInChildProcess(save_string));
+  EXPECT_TRUE(FieldTrialList::CreateTrialsFromString(save_string));
 
   // But it is an error to try to change to a different winner.
-  EXPECT_FALSE(FieldTrialList::CreateTrialsInChildProcess(
-      "Some name/Loser/"));
+  EXPECT_FALSE(FieldTrialList::CreateTrialsFromString("Some name/Loser/"));
 }
 
 TEST_F(FieldTrialTest, CreateFieldTrial) {
   EXPECT_TRUE(FieldTrialList::Find("Some_name") == NULL);
 
   FieldTrialList::CreateFieldTrial("Some_name", "Winner");
 
   FieldTrial* trial = FieldTrialList::Find("Some_name");
   ASSERT_NE(static_cast<FieldTrial*>(NULL), trial);
   EXPECT_EQ("Winner", trial->group_name());
   EXPECT_EQ("Some_name", trial->name());
 }
 
 TEST_F(FieldTrialTest, DuplicateFieldTrial) {
-  FieldTrial* trial =
-      new FieldTrial(
-          "Some_name", 10, "Default some name", next_year_, 12, 31);
+  FieldTrial* trial = FieldTrialList::FactoryGetFieldTrial(
+      "Some_name", 10, "Default some name", next_year_, 12, 31, NULL);
   trial->AppendGroup("Winner", 10);
 
   // It is OK if we redundantly specify a winner.
   FieldTrial* trial1 = FieldTrialList::CreateFieldTrial("Some_name", "Winner");
   EXPECT_TRUE(trial1 != NULL);
 
   // But it is an error to try to change to a different winner.
   FieldTrial* trial2 = FieldTrialList::CreateFieldTrial("Some_name", "Loser");
   EXPECT_TRUE(trial2 == NULL);
 }
 
 TEST_F(FieldTrialTest, MakeName) {
-  FieldTrial* trial =
-      new FieldTrial("Field Trial", 10, "Winner", next_year_, 12, 31);
+  FieldTrial* trial = FieldTrialList::FactoryGetFieldTrial(
+      "Field Trial", 10, "Winner", next_year_, 12, 31, NULL);
   trial->group();
   EXPECT_EQ("Histogram_Winner",
             FieldTrial::MakeName("Histogram", "Field Trial"));
 }
 
 TEST_F(FieldTrialTest, HashClientId) {
   double results[] = {
       FieldTrial::HashClientId("hi", "1"),
       FieldTrial::HashClientId("there", "1"),
   };
@@ skipping 55 matching lines @@
 }
 
 TEST_F(FieldTrialTest, UseOneTimeRandomization) {
   // Simply asserts that two trials using one-time randomization
   // that have different names, normally generate different results.
   //
   // Note that depending on the one-time random initialization, they
   // _might_ actually give the same result, but we know that given
   // the particular client_id we use for unit tests they won't.
   scoped_refptr<FieldTrial> trials[] = {
-    new FieldTrial("one", 100, "default", next_year_, 1, 1),
-    new FieldTrial("two", 100, "default", next_year_, 1, 1),
+    FieldTrialList::FactoryGetFieldTrial("one", 100, "default",
+                                          next_year_, 1, 1, NULL),
+    FieldTrialList::FactoryGetFieldTrial("two", 100, "default",
+                                          next_year_, 1, 1, NULL),
   };
 
   for (size_t i = 0; i < arraysize(trials); ++i) {
     trials[i]->UseOneTimeRandomization();
 
     for (int j = 0; j < 100; ++j) {
       trials[i]->AppendGroup("", 1);
     }
   }
 
   // The trials are most likely to give different results since they have
   // different names.
   ASSERT_NE(trials[0]->group(), trials[1]->group());
   ASSERT_NE(trials[0]->group_name(), trials[1]->group_name());
 }
 
 TEST_F(FieldTrialTest, DisableImmediately) {
-  FieldTrial* trial =
-      new FieldTrial("trial", 100, "default", next_year_, 12, 31);
+  int default_group_number = -1;
+  FieldTrial* trial = FieldTrialList::FactoryGetFieldTrial(
+      "trial", 100, "default", next_year_, 12, 31, &default_group_number);
   trial->Disable();
   ASSERT_EQ("default", trial->group_name());
-  ASSERT_EQ(FieldTrial::kDefaultGroupNumber, trial->group());
+  ASSERT_EQ(default_group_number, trial->group());
 }
 
 TEST_F(FieldTrialTest, DisableAfterInitialization) {
   FieldTrial* trial =
-      new FieldTrial("trial", 100, "default", next_year_, 12, 31);
+      FieldTrialList::FactoryGetFieldTrial("trial", 100, "default",
+                                            next_year_, 12, 31, NULL);
   trial->AppendGroup("non_default", 100);
   ASSERT_EQ("non_default", trial->group_name());
   trial->Disable();
   ASSERT_EQ("default", trial->group_name());
 }
 
+TEST_F(FieldTrialTest, ForcedFieldTrials) {
+  // Validate we keep the forced choice.
+  FieldTrial* forced_trial = FieldTrialList::CreateFieldTrial("Use the",
+                                                              "Force");
+  EXPECT_STREQ("Force", forced_trial->group_name().c_str());
+
+  int default_group_number = -1;
+  FieldTrial* factory_trial = FieldTrialList::FactoryGetFieldTrial(
+      "Use the", 1000, "default", next_year_, 12, 31, &default_group_number);
+  EXPECT_EQ(factory_trial, forced_trial);
+
+  int chosen_group = factory_trial->AppendGroup("Force", 100);
+  EXPECT_EQ(chosen_group, factory_trial->group());
+  int not_chosen_group = factory_trial->AppendGroup("Dark Side", 100);
+  EXPECT_NE(chosen_group, not_chosen_group);
+
+  // Since we didn't force the default group, we should not be returned the
+  // chosen group as the default group.
+  EXPECT_NE(default_group_number, chosen_group);
+  int new_group = factory_trial->AppendGroup("Duck Tape", 800);
+  EXPECT_NE(chosen_group, new_group);
+  // The new group should not be the default group either.
+  EXPECT_NE(default_group_number, new_group);
+
+  // Forcing the default should use the proper group ID.
+  forced_trial = FieldTrialList::CreateFieldTrial("Trial Name", "Default");
+  factory_trial = FieldTrialList::FactoryGetFieldTrial(
+      "Trial Name", 1000, "Default", next_year_, 12, 31, &default_group_number);
+  EXPECT_EQ(forced_trial, factory_trial);
+
+  int other_group = factory_trial->AppendGroup("Not Default", 100);
+  EXPECT_STREQ("Default", factory_trial->group_name().c_str());
+  EXPECT_EQ(default_group_number, factory_trial->group());
+  EXPECT_NE(other_group, factory_trial->group());
+
+  int new_other_group = factory_trial->AppendGroup("Not Default Either", 800);
+  EXPECT_NE(new_other_group, factory_trial->group());
+}
+
 }  // namespace base