Fix variations crashes when the chosen trial group is not in study.

components/variations/variations_seed_processor_unittest.cc

 // Copyright 2013 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 "components/variations/variations_seed_processor.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include <map>
@@ skipping 845 matching lines @@
 
   EXPECT_TRUE(CreateTrialFromStudy(study));
 
   base::FieldTrial* trial = base::FieldTrialList::Find("Study1");
   trial->Disable();
 
   EXPECT_EQ(ProcessedStudy::kGenericDefaultExperimentName,
             base::FieldTrialList::FindFullName("Study1"));
 }
 
+TEST_F(VariationsSeedProcessorTest, ExistingFieldTrial_ExpiredByConfig) {
+  static struct base::Feature kFeature {
+    "FeatureName", base::FEATURE_ENABLED_BY_DEFAULT
+  };
+  base::FieldTrialList field_trial_list(nullptr);
+
+  // In this case, an existing forced trial exists with a different default
+  // group than the study config, which is expired. This tests that we don't
+  // crash in such a case.
+  auto* trial = base::FieldTrialList::FactoryGetFieldTrial(
+      "Study1", 100, "ExistingDefault", base::FieldTrialList::kNoExpirationYear,
+      1, 1, base::FieldTrial::SESSION_RANDOMIZED, nullptr);
+  trial->AppendGroup("A", 100);
+  trial->SetForced();
+
+  Study study;
+  study.set_name("Study1");
+  const base::Time year_ago =
+      base::Time::Now() - base::TimeDelta::FromDays(365);
+  study.set_expiry_date(TimeToProtoTime(year_ago));
+  auto* exp1 = AddExperiment("A", 1, &study);
+  exp1->mutable_feature_association()->add_enable_feature(kFeature.name);
+  AddExperiment("Default", 1, &study);
+  study.set_default_experiment_name("Default");
+
+  EXPECT_TRUE(CreateTrialFromStudy(study));
+
+  // The expected effect is that processing the server config will expire
+  // the existing trial.
+  EXPECT_EQ("ExistingDefault", trial->group_name());
+}
+
+TEST_F(VariationsSeedProcessorTest, ExpiredStudy_NoDefaultGroup) {
+  static struct base::Feature kFeature {
+    "FeatureName", base::FEATURE_ENABLED_BY_DEFAULT
+  };
+  base::FieldTrialList field_trial_list(nullptr);
+
+  // Although it's not expected for the server to provide a study with an expiry
+  // date set, but not default experiment, this tests that we don't crash if
+  // that happens.
+  Study study;
+  study.set_name("Study1");
+  const base::Time year_ago =
+      base::Time::Now() - base::TimeDelta::FromDays(365);
+  study.set_expiry_date(TimeToProtoTime(year_ago));
+  auto* exp1 = AddExperiment("A", 1, &study);
+  exp1->mutable_feature_association()->add_enable_feature(kFeature.name);
+
+  EXPECT_TRUE(CreateTrialFromStudy(study));
+  EXPECT_EQ("VariationsDefaultExperiment",
+            base::FieldTrialList::FindFullName("Study1"));
+}
+
 TEST_F(VariationsSeedProcessorTest, LowEntropyStudyTest) {
   const std::string kTrial1Name = "A";
   const std::string kTrial2Name = "B";
   const std::string kGroup1Name = "AA";
   const std::string kDefaultName = "Default";
 
   VariationsSeed seed;
   Study* study1 = seed.add_study();
   study1->set_name(kTrial1Name);
   study1->set_consistency(variations::Study_Consistency_PERMANENT);
@@ skipping 26 matching lines @@
   // Since no experiment in study1 sends experiment IDs, it will use the high
   // entropy provider, which selects the non-default group.
   EXPECT_EQ(kGroup1Name, base::FieldTrialList::FindFullName(kTrial1Name));
 
   // Since an experiment in study2 has google_web_experiment_id set, it will use
   // the low entropy provider, which selects the default group.
   EXPECT_EQ(kDefaultName, base::FieldTrialList::FindFullName(kTrial2Name));
 }
 
 }  // namespace variations