Store and retrieve features from shared memory

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/memory/ptr_util.h"
 #include "base/metrics/field_trial.h"
+#include "base/metrics/persistent_memory_allocator.h"
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace base {
 
 namespace {
 
 const char kFeatureOnByDefaultName[] = "OnByDefault";
 struct Feature kFeatureOnByDefault {
@@ skipping 435 matching lines @@
   ClearFeatureListInstance();
   // This test case simulates the calling pattern found in code which does not
   // explicitly initialize the features list.
   // All IsEnabled() calls should return the default value in this scenario.
   EXPECT_EQ(nullptr, FeatureList::GetInstance());
   EXPECT_TRUE(FeatureList::IsEnabled(kFeatureOnByDefault));
   EXPECT_EQ(nullptr, FeatureList::GetInstance());
   EXPECT_FALSE(FeatureList::IsEnabled(kFeatureOffByDefault));
 }
 
+TEST_F(FeatureListTest, StoreAndRetrieveFeaturesFromSharedMemory) {

[Alexei Svitkine (slow), 2016/12/01 20:05:52]

Can you add testing for OVERRIDE_USE_DEFAULT state?

This would test to make sure the field trial gets associated (and would be
activated if the feature is queried) without forcing its state one way or
another.

[lawrencewu, 2016/12/02 19:24:46]

Done.

+  std::unique_ptr<base::FeatureList> feature_list(new base::FeatureList);
+
+  // Create some overrides.
+  feature_list->RegisterOverride(kFeatureOffByDefaultName,
+                                 FeatureList::OVERRIDE_ENABLE_FEATURE, nullptr);
+  feature_list->RegisterOverride(
+      kFeatureOnByDefaultName, FeatureList::OVERRIDE_DISABLE_FEATURE, nullptr);
+  feature_list->FinalizeInitialization();
+
+  // Create an allocator and store the overrides.
+  std::unique_ptr<SharedMemory> shm(new SharedMemory());
+  shm->CreateAndMapAnonymous(4 << 10);
+  SharedPersistentMemoryAllocator allocator(std::move(shm), 1, "", false);
+  feature_list->AddFeaturesToAllocator(&allocator);
+
+  std::unique_ptr<base::FeatureList> feature_list2(new base::FeatureList);
+
+  // Check that the new feature list is empty.
+  EXPECT_FALSE(feature_list2->IsFeatureOverriddenFromCommandLine(
+      kFeatureOffByDefaultName, FeatureList::OVERRIDE_ENABLE_FEATURE));
+  EXPECT_FALSE(feature_list2->IsFeatureOverriddenFromCommandLine(
+      kFeatureOnByDefaultName, FeatureList::OVERRIDE_DISABLE_FEATURE));
+
+  feature_list2->InitializeFromSharedMemory(&allocator);
+  // Check that the new feature list now has 2 overrides.
+  EXPECT_TRUE(feature_list2->IsFeatureOverriddenFromCommandLine(
+      kFeatureOffByDefaultName, FeatureList::OVERRIDE_ENABLE_FEATURE));
+  EXPECT_TRUE(feature_list2->IsFeatureOverriddenFromCommandLine(
+      kFeatureOnByDefaultName, FeatureList::OVERRIDE_DISABLE_FEATURE));
+}
+
 }  // namespace base