Feature to disable field trials in old versions of Chromium. Field trials...

base/metrics/field_trial_unittest.cc

 // Copyright (c) 2010 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/stringprintf.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
 
 class FieldTrialTest : public testing::Test {
  public:
   FieldTrialTest() : trial_list_() { }
 
  private:
   FieldTrialList trial_list_;
 };
 
 // Test registration, and also check that destructors are called for trials
 // (and that Purify 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);
-  EXPECT_EQ(FieldTrial::kNotParticipating, trial1->group());
+  FieldTrial* trial1 = new FieldTrial(name1, 10, "default name 1 test");
+  EXPECT_EQ(FieldTrial::kNotFinalized, trial1->group_);
   EXPECT_EQ(name1, trial1->name());
   EXPECT_EQ("", trial1->group_name());
 
   trial1->AppendGroup("", 7);
 
   EXPECT_EQ(trial1, FieldTrialList::Find(name1));
   EXPECT_FALSE(FieldTrialList::Find(name2));
 
-  FieldTrial* trial2 = new FieldTrial(name2, 10);
-  EXPECT_EQ(FieldTrial::kNotParticipating, trial2->group());
+  FieldTrial* trial2 = new FieldTrial(name2, 10, "default name 2 test");
+  EXPECT_EQ(FieldTrial::kNotFinalized, trial2->group_);
   EXPECT_EQ(name2, trial2->name());
   EXPECT_EQ("", trial2->group_name());
 
   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);
+    FieldTrial* trial_true = new FieldTrial(always_true, 10,
+                                            default_always_true);
     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);
+    FieldTrial* trial_false = new FieldTrial(always_false, 10,
+                                             default_always_false);
     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;
   do {
     std::string name = StringPrintf("trial%d", ++counter);
-    trial = new FieldTrial(name, 10);
+    trial = new FieldTrial(name, 10, winner);
     trial->AppendGroup(loser, 5);  // 50% chance of not being chosen.
-  } while (trial->group() != FieldTrial::kNotParticipating);
+    // If a group is not assigned, group_ will be kNotFinalized.
+  } while (trial->group_ != FieldTrial::kNotFinalized);
 
-  // Now add a winner with all remaining probability.
-  trial->AppendGroup(winner, FieldTrial::kAllRemainingProbability);
+  // A group is not assigned. Now finalize it by calling group() and assert
+  // that we got the default group which is winner.
+  EXPECT_EQ(FieldTrial::kDefaultGroupNumber, 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);
-    scoped_refptr<FieldTrial> trial(new FieldTrial(name, 2));
+    std::string default_group_name = base::StringPrintf("Default FiftyFifty%d",
+                                                        ++counter);
+    scoped_refptr<FieldTrial> trial(new FieldTrial(name, 2,
+                                                   default_group_name));
     trial->AppendGroup("first", 1);  // 50% chance of being chosen.
-    if (trial->group() != FieldTrial::kNotParticipating) {
+    // 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::kNotParticipating, trial->group());
+    // If group is not assigned, then add another group and it should always be
+    // chosen at this point.
+    trial->AppendGroup("second", 1);
+    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;
-    FieldTrial* trial = new FieldTrial(name, 10);
+    default_group_name[0] = i;
+    FieldTrial* trial = new FieldTrial(name, 10, default_group_name);
     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);
+  FieldTrial* trial = new FieldTrial(name, group_count, default_group_name);
   int winner_index(-2);
   std::string winner_name;
 
   for (int i = 1; i <= group_count; ++i) {
     int might_win = trial->AppendGroup("", 1);
 
-    if (trial->group() == might_win) {
+    // 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);
   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.
+  scoped_refptr<FieldTrial> trial;
+  trial = new FieldTrial(name, 1000000000, default_group_name, 2011, 1, 1);
+  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());
+
+  // And that default_group_name should ALWAYS win.
+  EXPECT_EQ(default_group_name, trial->group_name());
+}
+
 TEST_F(FieldTrialTest, Save) {
   std::string save_string;
 
-  FieldTrial* trial = new FieldTrial("Some name", 10);
+  FieldTrial* trial = new FieldTrial("Some name", 10, "Default some name");
   // There is no winner yet, so no textual group name is associated with trial.
   EXPECT_EQ("", trial->group_name());
   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);
+  FieldTrial* trial2 = new FieldTrial("xxx", 10, "Default xxx");
   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);
@@ skipping 12 matching lines @@
 }
 
 TEST_F(FieldTrialTest, BogusRestore) {
   EXPECT_FALSE(FieldTrialList::StringAugmentsState("MissingSlash"));
   EXPECT_FALSE(FieldTrialList::StringAugmentsState("MissingGroupName/"));
   EXPECT_FALSE(FieldTrialList::StringAugmentsState("MissingFinalSlash/gname"));
   EXPECT_FALSE(FieldTrialList::StringAugmentsState("/noname, only group/"));
 }
 
 TEST_F(FieldTrialTest, DuplicateRestore) {
-  FieldTrial* trial = new FieldTrial("Some name", 10);
+  FieldTrial* trial = new FieldTrial("Some name", 10, "Default some name");
   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::StringAugmentsState(save_string));
 
   // But it is an error to try to change to a different winner.
   EXPECT_FALSE(FieldTrialList::StringAugmentsState("Some name/Loser/"));
 }
 
 TEST_F(FieldTrialTest, MakeName) {
-  FieldTrial* trial = new FieldTrial("Field Trial", 10);
-  trial->AppendGroup("Winner", 10);
+  FieldTrial* trial = new FieldTrial("Field Trial", 10, "Winner");
+  trial->group();
   EXPECT_EQ("Histogram_Winner",
             FieldTrial::MakeName("Histogram", "Field Trial"));
 }
 
 }  // namespace base