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// Copyright 2022 The Chromium Authors
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
#include <stdint.h>
#include <memory>
#include "base/feature_list.h"
#include "base/functional/bind.h"
#include "base/strings/stringprintf.h"
#include "base/test/scoped_feature_list.h"
#include "components/variations/entropy_provider.h"
#include "components/variations/proto/layer.pb.h"
#include "components/variations/proto/study.pb.h"
#include "components/variations/proto/variations_seed.pb.h"
#include "components/variations/variations_layers.h"
#include "components/variations/variations_seed_processor.h"
#include "components/variations/variations_test_utils.h"
#include "testing/gtest/include/gtest/gtest-param-test.h"
#include "testing/gtest/include/gtest/gtest.h"
namespace variations {
namespace {
struct TestStudyConfig {
std::string_view name;
bool add_salt = false;
bool add_google_web_experiment_id = false;
bool use_limited_entropy = false;
};
const int kLayerId = 1;
const int kLayerMemberId = 101;
const TestStudyConfig kTestStudyConfigs[] = {
{.name = "Study_NoSalt"},
{.name = "Study_WithSalt", .add_salt = true},
{.name = "Study_NoSalt_LowEntropy", .add_google_web_experiment_id = true},
{.name = "Study_WithSalt_LowEntropy",
.add_salt = true,
.add_google_web_experiment_id = true},
// Limited entropy test configs:
{.name = "Study_NoSalt_LimitedEntropy", .use_limited_entropy = true},
{.name = "Study_WithSalt_LimitedEntropy",
.add_salt = true,
.use_limited_entropy = true},
{.name = "Study_NoSalt_WithGoogleId_LimitedEntropy",
.add_google_web_experiment_id = true,
.use_limited_entropy = true},
{.name = "Study_WithSalt_WithGoogleId_LimitedEntropy",
.add_salt = true,
.add_google_web_experiment_id = true,
.use_limited_entropy = true},
};
// Adds a permanently consistent study with many groups to the seed. This
// ensures that they are sensitive to any changes in the group assignment
// algorithms, which should not change between releases. The function also
// applies any settings from `config`.
void SetupStudy(VariationsSeed* seed, const TestStudyConfig& config) {
Study* study = seed->add_study();
study->set_name(std::string(config.name));
study->set_consistency(Study_Consistency_PERMANENT);
if (config.add_salt) {
study->set_randomization_seed(0x1234);
}
for (int i = 0; i < 100; i++) {
Study::Experiment* experiment = study->add_experiment();
experiment->set_name(base::StringPrintf("group%02d", i));
experiment->set_probability_weight(1);
if (config.add_google_web_experiment_id) {
experiment->set_google_web_experiment_id(i);
}
}
if (config.use_limited_entropy) {
LayerMemberReference* reference = study->mutable_layer();
reference->set_layer_id(kLayerId);
reference->add_layer_member_ids(kLayerMemberId);
}
}
void SetupLimitedLayer(VariationsSeed* seed) {
Layer* layer = seed->add_layers();
layer->set_id(1);
layer->set_num_slots(100);
layer->set_entropy_mode(Layer::LIMITED);
Layer_LayerMember* layer_member = layer->add_members();
layer_member->set_id(101);
Layer_LayerMember_SlotRange* slot = layer_member->add_slots();
slot->set_start(0);
slot->set_end(99);
}
void SetupSeed(VariationsSeed* seed) {
bool add_limited_layer = false;
for (const TestStudyConfig& config : kTestStudyConfigs) {
SetupStudy(seed, config);
add_limited_layer |= config.use_limited_entropy;
}
// This ensures there is only one limited layer in the seed. It is referenced
// by all test studies.
if (add_limited_layer) {
SetupLimitedLayer(seed);
}
}
void ProcessSeed(EntropyProviders&& entropy_providers) {
VariationsSeed seed;
SetupSeed(&seed);
auto client_state = CreateDummyClientFilterableState();
base::FeatureList feature_list;
VariationsLayers layers(seed, entropy_providers);
VariationsSeedProcessor().CreateTrialsFromSeed(
seed, *client_state, base::BindRepeating(NoopUIStringOverrideCallback),
entropy_providers, layers, &feature_list);
}
} // namespace
// The following tests differ only by the input entropy providers, and they
// each check that the group assignments for the permanent consistency studies
// match the values from when the test was written. New changes should not
// break consistency with these assignments.
// The HighEntropyNil tests pass an empty high entropy, which simulates the
// behavior clients that disable high entropy randomization, such as clients
// not opted in to UMA, and clients on platforms like webview where high entropy
// randomization is not supported.
TEST(VariationsAntishuffleTest, HighEntropyNil_LowEntropy0) {
ProcessSeed(EntropyProviders("", {0, 8000},
/*limited_entropy_value=*/"not_used"));
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_NoSalt"), "group87");
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_WithSalt"), "group22");
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_NoSalt_LowEntropy"),
"group10");
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_WithSalt_LowEntropy"),
"group22");
}
TEST(VariationsAntishuffleTest, HighEntropyId0_LowEntropy0) {
ProcessSeed(EntropyProviders("clientid_0", {0, 8000},
/*limited_entropy_value=*/"not_used"));
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_NoSalt"), "group64");
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_WithSalt"), "group15");
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_NoSalt_LowEntropy"),
"group10");
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_WithSalt_LowEntropy"),
"group22");
}
TEST(VariationsAntishuffleTest, HighEntropyId1_LowEntropy0) {
ProcessSeed(EntropyProviders("clientid_1", {0, 8000},
/*limited_entropy_value=*/"not_used"));
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_NoSalt"), "group02");
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_WithSalt"), "group40");
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_NoSalt_LowEntropy"),
"group10");
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_WithSalt_LowEntropy"),
"group22");
}
TEST(VariationsAntishuffleTest, HighEntropyNil_LowEntropy7999) {
ProcessSeed(EntropyProviders("", {7999, 8000},
/*limited_entropy_value=*/"not_used"));
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_NoSalt"), "group43");
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_WithSalt"), "group48");
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_NoSalt_LowEntropy"),
"group97");
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_WithSalt_LowEntropy"),
"group48");
}
TEST(VariationsAntishuffleTest, HighEntropyId0_LowEntropy7999) {
ProcessSeed(EntropyProviders("clientid_0", {7999, 8000},
/*limited_entropy_value=*/"not_used"));
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_NoSalt"), "group64");
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_WithSalt"), "group15");
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_NoSalt_LowEntropy"),
"group97");
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_WithSalt_LowEntropy"),
"group48");
}
TEST(VariationsAntishuffleTest, HighEntropyId1_LowEntropy7999) {
ProcessSeed(EntropyProviders("clientid_1", {7999, 8000},
/*limited_entropy_value=*/"not_used"));
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_NoSalt"), "group02");
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_WithSalt"), "group40");
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_NoSalt_LowEntropy"),
"group97");
EXPECT_EQ(base::FieldTrialList::FindFullName("Study_WithSalt_LowEntropy"),
"group48");
}
TEST(VariationsAntishuffleTest, LimitedEntropyNil) {
ProcessSeed(EntropyProviders("not_used", {0, 8000},
/*limited_entropy_value=*/std::string_view()));
EXPECT_FALSE(
base::FieldTrialList::TrialExists("Study_NoSalt_LimitedEntropy"));
EXPECT_FALSE(
base::FieldTrialList::TrialExists("Study_WithSalt_LimitedEntropy"));
EXPECT_FALSE(base::FieldTrialList::TrialExists(
"Study_NoSalt_WithGoogleId_LimitedEntropy"));
EXPECT_FALSE(base::FieldTrialList::TrialExists(
"Study_WithSalt_WithGoogleId_LimitedEntropy"));
EXPECT_TRUE(base::FieldTrialList::TrialExists("Study_NoSalt"));
EXPECT_TRUE(base::FieldTrialList::TrialExists("Study_WithSalt"));
EXPECT_TRUE(base::FieldTrialList::TrialExists("Study_NoSalt_LowEntropy"));
EXPECT_TRUE(base::FieldTrialList::TrialExists("Study_WithSalt_LowEntropy"));
}
TEST(VariationsAntishuffleTest, LimitedEntropyRandomizationSource) {
struct RandomizationConfig {
std::string limited_entropy_value;
struct Expectation {
std::string study;
std::string group;
};
std::vector<Expectation> expectations;
} test_cases[] = {
// Group selections of "Study_WithSalt_LimitedEntropy" and
// "Study_WithSalt_WithGoogleId_LimitedEntropy" are the same because they
// are randomized from the same entropy provider, entropy value, and study
// salt.
{"limited_0",
{{"Study_NoSalt_LimitedEntropy", "group03"},
{"Study_WithSalt_LimitedEntropy", "group02"},
{"Study_NoSalt_WithGoogleId_LimitedEntropy", "group19"},
{"Study_WithSalt_WithGoogleId_LimitedEntropy", "group02"}}},
{"limited_1",
{{"Study_NoSalt_LimitedEntropy", "group63"},
{"Study_WithSalt_LimitedEntropy", "group17"},
{"Study_NoSalt_WithGoogleId_LimitedEntropy", "group57"},
{"Study_WithSalt_WithGoogleId_LimitedEntropy", "group17"}}}};
for (const auto& test_case : test_cases) {
base::test::ScopedFeatureList scoped_feature_list;
scoped_feature_list.InitWithEmptyFeatureAndFieldTrialLists();
ProcessSeed(EntropyProviders("not_used", {0, 8000},
test_case.limited_entropy_value));
for (const auto& expectation : test_case.expectations) {
EXPECT_EQ(base::FieldTrialList::FindFullName(expectation.study),
expectation.group);
}
}
}
} // namespace variations
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