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-rw-r--r--base/metrics/field_trial_unittest.cc125
1 files changed, 118 insertions, 7 deletions
diff --git a/base/metrics/field_trial_unittest.cc b/base/metrics/field_trial_unittest.cc
index 3357085..a790add 100644
--- a/base/metrics/field_trial_unittest.cc
+++ b/base/metrics/field_trial_unittest.cc
@@ -6,14 +6,18 @@
#include "base/metrics/field_trial.h"
+#include "base/rand_util.h"
#include "base/stringprintf.h"
+#include "base/string_number_conversions.h"
#include "testing/gtest/include/gtest/gtest.h"
+#include <limits>
+
namespace base {
class FieldTrialTest : public testing::Test {
public:
- FieldTrialTest() : trial_list_() {
+ FieldTrialTest() : trial_list_("client_id") {
Time now = Time::NowFromSystemTime();
TimeDelta oneYear = TimeDelta::FromDays(365);
Time::Exploded exploded;
@@ -224,9 +228,10 @@ TEST_F(FieldTrialTest, Save) {
new FieldTrial(
"Some name", 10, "Default some name", next_year_, 12, 31);
// 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("Some name/Default some name/", save_string);
+ EXPECT_EQ("", save_string);
save_string.clear();
// Create a winning group.
@@ -265,10 +270,10 @@ TEST_F(FieldTrialTest, Restore) {
TEST_F(FieldTrialTest, BogusRestore) {
EXPECT_FALSE(FieldTrialList::CreateTrialsInChildProcess("MissingSlash"));
EXPECT_FALSE(FieldTrialList::CreateTrialsInChildProcess("MissingGroupName/"));
- EXPECT_FALSE(
- FieldTrialList::CreateTrialsInChildProcess("MissingFinalSlash/gname"));
- EXPECT_FALSE(
- FieldTrialList::CreateTrialsInChildProcess("/noname, only group/"));
+ EXPECT_FALSE(FieldTrialList::CreateTrialsInChildProcess(
+ "MissingFinalSlash/gname"));
+ EXPECT_FALSE(FieldTrialList::CreateTrialsInChildProcess(
+ "noname, only group/"));
}
TEST_F(FieldTrialTest, DuplicateRestore) {
@@ -284,7 +289,8 @@ TEST_F(FieldTrialTest, DuplicateRestore) {
EXPECT_TRUE(FieldTrialList::CreateTrialsInChildProcess(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::CreateTrialsInChildProcess(
+ "Some name/Loser/"));
}
TEST_F(FieldTrialTest, CreateFieldTrial) {
@@ -321,4 +327,109 @@ TEST_F(FieldTrialTest, MakeName) {
FieldTrial::MakeName("Histogram", "Field Trial"));
}
+TEST_F(FieldTrialTest, HashClientId) {
+ double results[] = {
+ FieldTrial::HashClientId("hi", "1"),
+ FieldTrial::HashClientId("there", "1"),
+ };
+ ASSERT_NE(results[0], results[1]);
+ for (size_t i = 0; i < arraysize(results); ++i) {
+ ASSERT_LE(0.0, results[i]);
+ ASSERT_GT(1.0, results[i]);
+ }
+
+ ASSERT_EQ(FieldTrial::HashClientId("yo", "1"),
+ FieldTrial::HashClientId("yo", "1"));
+ ASSERT_NE(FieldTrial::HashClientId("yo", "something"),
+ FieldTrial::HashClientId("yo", "else"));
+}
+
+TEST_F(FieldTrialTest, HashClientIdIsUniform) {
+ // Choose a random start number but go sequentially from there, so
+ // that each test tries a different range but we never provide uniformly
+ // distributed input data.
+ int current_number = RandInt(0, std::numeric_limits<int>::max());
+
+ // The expected value of a random distribution is the average over all
+ // samples as the number of samples approaches infinity. For a uniform
+ // distribution from [0.0, 1.0) this would be 0.5.
+ //
+ // We do kSamplesBetweenChecks at a time and check if the value has converged
+ // to a narrow interval around 0.5. A non-uniform distribution would likely
+ // converge at something different, or not converge consistently within this
+ // range (i.e. the test would start timing out occasionally).
+ int kSamplesBetweenChecks = 300;
+ int num_samples = 0;
+ double total_value = 0.0;
+ while (true) {
+ for (int i = 0; i < kSamplesBetweenChecks; ++i) {
+ total_value += FieldTrial::HashClientId(
+ IntToString(current_number++), "salt");
+ num_samples++;
+ }
+
+ double average = total_value / num_samples;
+ double kExpectedMin = 0.48;
+ double kExpectedMax = 0.52;
+
+ if (num_samples > 1000 &&
+ (average < kExpectedMin || average > kExpectedMax)) {
+ // Only printed once we have enough samples that it's very unlikely
+ // things haven't converged.
+ printf("After %d samples, the average was %f, outside the expected\n"
+ "range (%f, %f). We will add more samples and check after every\n"
+ "%d samples. If the average does not converge, something\n"
+ "is broken. If it does converge, the test will pass.\n",
+ num_samples, average,
+ kExpectedMin, kExpectedMax, kSamplesBetweenChecks);
+ } else {
+ // Success.
+ break;
+ }
+ }
+}
+
+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),
+ };
+
+ 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);
+ trial->Disable();
+ ASSERT_EQ("default", trial->group_name());
+ ASSERT_EQ(FieldTrial::kDefaultGroupNumber, trial->group());
+}
+
+TEST_F(FieldTrialTest, DisableAfterInitialization) {
+ FieldTrial* trial =
+ new FieldTrial("trial", 100, "default", next_year_, 12, 31);
+ trial->AppendGroup("non_default", 100);
+ ASSERT_EQ("non_default", trial->group_name());
+ trial->Disable();
+ ASSERT_EQ("default", trial->group_name());
+}
+
} // namespace base