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// Copyright (c) 2006-2009 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/field_trial.h"
#include "base/string_util.h"
#include "testing/gtest/include/gtest/gtest.h"
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(trial1->group(), FieldTrial::kNotParticipating);
EXPECT_EQ(trial1->name(), name1);
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(trial2->group(), FieldTrial::kNotParticipating);
EXPECT_EQ(trial2->name(), name2);
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 always_false[] = " 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;
always_false[0] = i;
FieldTrial* trial_true = new FieldTrial(always_true, 10);
const std::string winner = "_TheWinner";
int winner_group = trial_true->AppendGroup(winner, 10);
EXPECT_EQ(trial_true->group(), winner_group);
EXPECT_EQ(trial_true->group_name(), winner);
FieldTrial* trial_false = new FieldTrial(always_false, 10);
int loser_group = trial_false->AppendGroup("ALoser", 0);
EXPECT_NE(trial_false->group(), loser_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->AppendGroup(loser, 5); // 50% chance of not being chosen.
} while (trial->group() != FieldTrial::kNotParticipating);
// Now add a winner with all remaining probability.
trial->AppendGroup(winner, FieldTrial::kAllRemainingProbability);
// And that winner should ALWAYS win.
EXPECT_EQ(winner, trial->group_name());
}
TEST_F(FieldTrialTest, MiddleProbabilities) {
char name[] = " 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);
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";
int group_count(10);
FieldTrial* trial = new FieldTrial(name, group_count);
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) {
EXPECT_EQ(winner_index, -2);
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(winner_name, trial->group_name());
}
TEST_F(FieldTrialTest, Save) {
std::string save_string;
FieldTrial* trial = new FieldTrial("Some name", 10);
// 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(save_string, "Some name/Winner/");
save_string.clear();
// Create a second trial and winning group.
FieldTrial* trial2 = new FieldTrial("xxx", 10);
trial2->AppendGroup("yyyy", 10);
FieldTrialList::StatesToString(&save_string);
// We assume names are alphabetized... though this is not critical.
EXPECT_EQ(save_string, "Some name/Winner/xxx/yyyy/");
}
TEST_F(FieldTrialTest, Restore) {
EXPECT_TRUE(FieldTrialList::Find("Some_name") == NULL);
EXPECT_TRUE(FieldTrialList::Find("xxx") == NULL);
FieldTrialList::StringAugmentsState("Some_name/Winner/xxx/yyyy/");
FieldTrial* trial = FieldTrialList::Find("Some_name");
ASSERT_NE(static_cast<FieldTrial*>(NULL), trial);
EXPECT_EQ(trial->group_name(), "Winner");
EXPECT_EQ(trial->name(), "Some_name");
trial = FieldTrialList::Find("xxx");
ASSERT_NE(static_cast<FieldTrial*>(NULL), trial);
EXPECT_EQ(trial->group_name(), "yyyy");
EXPECT_EQ(trial->name(), "xxx");
}
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);
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/"));
}
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