Rename test helper for registering field trial keys

This new name emphasizes that the field trial keys are only allowed
within the current scope. We already have test::ScopedFieldTrials that
can be used to ensure that the global field trials string itself is
isolated.

Bug: webrtc:14705
Change-Id: I8b66bbd9c11d97985292c334d2d3496a047074a1
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/284862
Commit-Queue: Emil Lundmark <lndmrk@webrtc.org>
Reviewed-by: Harald Alvestrand <hta@webrtc.org>
Cr-Commit-Position: refs/heads/main@{#38796}

api/field_trials_unittest.cc

@@ -28,11 +28,11 @@ namespace webrtc {
 namespace {
 
 using ::testing::NotNull;
+using ::webrtc::field_trial::FieldTrialsAllowedInScopeForTesting;
 using ::webrtc::field_trial::InitFieldTrialsFromString;
-using ::webrtc::field_trial::ScopedGlobalFieldTrialsForTesting;
 
 TEST(FieldTrialsTest, EmptyStringHasNoEffect) {
-  ScopedGlobalFieldTrialsForTesting g({"MyCoolTrial"});
+  FieldTrialsAllowedInScopeForTesting k({"MyCoolTrial"});
   FieldTrials f("");
   f.RegisterKeysForTesting({"MyCoolTrial"});
 
@@ -53,7 +53,7 @@ TEST(FieldTrialsTest, EnabledDisabledMustBeFirstInValue) {
 }
 
 TEST(FieldTrialsTest, FieldTrialsDoesNotReadGlobalString) {
-  ScopedGlobalFieldTrialsForTesting g({"MyCoolTrial", "MyUncoolTrial"});
+  FieldTrialsAllowedInScopeForTesting k({"MyCoolTrial", "MyUncoolTrial"});
   static constexpr char s[] = "MyCoolTrial/Enabled/MyUncoolTrial/Disabled/";
   InitFieldTrialsFromString(s);
   FieldTrials f("");
@@ -64,7 +64,7 @@ TEST(FieldTrialsTest, FieldTrialsDoesNotReadGlobalString) {
 }
 
 TEST(FieldTrialsTest, FieldTrialsWritesGlobalString) {
-  ScopedGlobalFieldTrialsForTesting g({"MyCoolTrial", "MyUncoolTrial"});
+  FieldTrialsAllowedInScopeForTesting k({"MyCoolTrial", "MyUncoolTrial"});
   FieldTrials f("MyCoolTrial/Enabled/MyUncoolTrial/Disabled/");
   EXPECT_TRUE(webrtc::field_trial::IsEnabled("MyCoolTrial"));
   EXPECT_TRUE(webrtc::field_trial::IsDisabled("MyUncoolTrial"));
@@ -95,7 +95,7 @@ TEST(FieldTrialsTest, FieldTrialsSupportsSeparateInstances) {
 }
 
 TEST(FieldTrialsTest, NonGlobalFieldTrialsInstanceDoesNotModifyGlobalString) {
-  ScopedGlobalFieldTrialsForTesting g({"SomeString"});
+  FieldTrialsAllowedInScopeForTesting k({"SomeString"});
   std::unique_ptr<FieldTrials> f =
       FieldTrials::CreateNoGlobal("SomeString/Enabled/");
   ASSERT_THAT(f, NotNull());
@@ -123,7 +123,7 @@ TEST(FieldTrialsTest, NonGlobalFieldTrialsSupportSimultaneousInstances) {
 }
 
 TEST(FieldTrialsTest, GlobalAndNonGlobalFieldTrialsAreDisjoint) {
-  ScopedGlobalFieldTrialsForTesting g({"SomeString", "SomeOtherString"});
+  FieldTrialsAllowedInScopeForTesting k({"SomeString", "SomeOtherString"});
   FieldTrials f1("SomeString/Enabled/");
   std::unique_ptr<FieldTrials> f2 =
       FieldTrials::CreateNoGlobal("SomeOtherString/Enabled/");
@@ -139,7 +139,7 @@ TEST(FieldTrialsTest, GlobalAndNonGlobalFieldTrialsAreDisjoint) {
 }
 
 TEST(FieldTrialsTest, FieldTrialBasedConfigReadsGlobalString) {
-  ScopedGlobalFieldTrialsForTesting g({"MyCoolTrial", "MyUncoolTrial"});
+  FieldTrialsAllowedInScopeForTesting k({"MyCoolTrial", "MyUncoolTrial"});
   static constexpr char s[] = "MyCoolTrial/Enabled/MyUncoolTrial/Disabled/";
   InitFieldTrialsFromString(s);
   FieldTrialBasedConfig f;

rtc_base/experiments/field_trial_parser_unittest.cc

@@ -30,17 +30,15 @@ struct DummyExperiment {
   FieldTrialParameter<std::string> hash =
       FieldTrialParameter<std::string>("h", "a80");
 
-  field_trial::ScopedGlobalFieldTrialsForTesting g{{kDummyExperiment}};
+  field_trial::FieldTrialsAllowedInScopeForTesting k{{kDummyExperiment}};
+
+  DummyExperiment()
+      : DummyExperiment(field_trial::FindFullName(kDummyExperiment)) {}
 
   explicit DummyExperiment(absl::string_view field_trial) {
     ParseFieldTrial({&enabled, &factor, &retries, &size, &ping, &hash},
                     field_trial);
   }
-  DummyExperiment() {
-    std::string trial_string = field_trial::FindFullName(kDummyExperiment);
-    ParseFieldTrial({&enabled, &factor, &retries, &size, &ping, &hash},
-                    trial_string);
-  }
 };
 
 enum class CustomEnum {

system_wrappers/include/field_trial.h

@@ -98,11 +98,16 @@ bool FieldTrialsStringIsValid(absl::string_view trials_string);
 std::string MergeFieldTrialsStrings(absl::string_view first,
                                     absl::string_view second);
 
-// RAII type that ensures global state is consistent between tests.
-class ScopedGlobalFieldTrialsForTesting {
+// This helper allows to temporary "register" a field trial within the current
+// scope. This is only useful for tests that use the global field trial string,
+// otherwise you can use `webrtc::FieldTrialsRegistry`.
+//
+// If you want to isolate changes to the global field trial string itself within
+// the current scope you should use `webrtc::test::ScopedFieldTrials`.
+class FieldTrialsAllowedInScopeForTesting {
  public:
-  explicit ScopedGlobalFieldTrialsForTesting(flat_set<std::string> keys);
-  ~ScopedGlobalFieldTrialsForTesting();
+  explicit FieldTrialsAllowedInScopeForTesting(flat_set<std::string> keys);
+  ~FieldTrialsAllowedInScopeForTesting();
 };
 
 }  // namespace field_trial

system_wrappers/source/field_trial.cc

@@ -168,12 +168,12 @@ const char* GetFieldTrialString() {
   return trials_init_string;
 }
 
-ScopedGlobalFieldTrialsForTesting::ScopedGlobalFieldTrialsForTesting(
+FieldTrialsAllowedInScopeForTesting::FieldTrialsAllowedInScopeForTesting(
     flat_set<std::string> keys) {
   TestKeys() = std::move(keys);
 }
 
-ScopedGlobalFieldTrialsForTesting::~ScopedGlobalFieldTrialsForTesting() {
+FieldTrialsAllowedInScopeForTesting::~FieldTrialsAllowedInScopeForTesting() {
   TestKeys().clear();
 }