Allow trials to associate without overriding a feature.

base/feature_list_unittest.cc

 // Copyright 2015 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.
 
 #include "base/feature_list.h"
 
 #include <stddef.h>
 
+#include <algorithm>
 #include <utility>
 
 #include "base/format_macros.h"
 #include "base/macros.h"
 #include "base/metrics/field_trial.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
@@ skipping 152 matching lines @@
 
     const bool expected_enabled_2 =
         (test_case.trial2_state == FeatureList::OVERRIDE_ENABLE_FEATURE);
     EXPECT_EQ(expected_enabled_2, FeatureList::IsEnabled(kFeatureOffByDefault));
     // The above should have activated |trial2|.
     EXPECT_TRUE(FieldTrialList::IsTrialActive(trial1->trial_name()));
     EXPECT_TRUE(FieldTrialList::IsTrialActive(trial2->trial_name()));
   }
 }
 
+TEST_F(FeatureListTest, FieldTrialAssociateUseDefault) {
+  FieldTrialList field_trial_list(nullptr);
+  scoped_ptr<FeatureList> feature_list(new FeatureList);
+
+  FieldTrial* trial1 = FieldTrialList::CreateFieldTrial("TrialExample1", "A");
+  FieldTrial* trial2 = FieldTrialList::CreateFieldTrial("TrialExample2", "B");
+  feature_list->RegisterFieldTrialOverride(
+      kFeatureOnByDefaultName, FeatureList::OVERRIDE_USE_DEFAULT, trial1);
+  feature_list->RegisterFieldTrialOverride(
+      kFeatureOffByDefaultName, FeatureList::OVERRIDE_USE_DEFAULT, trial2);
+  RegisterFeatureListInstance(std::move(feature_list));
+
+  // Initially, neither trial should be active.
+  EXPECT_FALSE(FieldTrialList::IsTrialActive(trial1->trial_name()));
+  EXPECT_FALSE(FieldTrialList::IsTrialActive(trial2->trial_name()));
+
+  // Check the feature enabled state is its default.
+  EXPECT_TRUE(FeatureList::IsEnabled(kFeatureOnByDefault));
+  // The above should have activated |trial1|.
+  EXPECT_TRUE(FieldTrialList::IsTrialActive(trial1->trial_name()));
+  EXPECT_FALSE(FieldTrialList::IsTrialActive(trial2->trial_name()));
+
+  // Check the feature enabled state is its default.
+  EXPECT_FALSE(FeatureList::IsEnabled(kFeatureOffByDefault));
+  // The above should have activated |trial2|.
+  EXPECT_TRUE(FieldTrialList::IsTrialActive(trial1->trial_name()));
+  EXPECT_TRUE(FieldTrialList::IsTrialActive(trial2->trial_name()));
+}
+
 TEST_F(FeatureListTest, CommandLineTakesPrecedenceOverFieldTrial) {
   ClearFeatureListInstance();
 
   FieldTrialList field_trial_list(nullptr);
   scoped_ptr<FeatureList> feature_list(new FeatureList);
 
   // The feature is explicitly enabled on the command-line.
   feature_list->InitializeFromCommandLine(kFeatureOffByDefaultName, "");
 
   // But the FieldTrial would set the feature to disabled.
@@ skipping 158 matching lines @@
   scoped_ptr<FeatureList> feature_list(new FeatureList);
   feature_list->InitializeFromCommandLine("A,OffByDefault<Trial,X", "D");
   RegisterFeatureListInstance(std::move(feature_list));
 
   EXPECT_FALSE(FieldTrialList::IsTrialActive("Trial"));
   EXPECT_TRUE(FeatureList::IsEnabled(kFeatureOffByDefault));
   EXPECT_TRUE(FieldTrialList::IsTrialActive("Trial"));
 }
 
 }  // namespace base