Initial implementation of FeatureList in base/.

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 "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+namespace {
+
+const char kFeatureOnByDefaultName[] = "OnByDefault";
+struct Feature kFeatureOnByDefault {
+  kFeatureOnByDefaultName, FEATURE_ENABLED_BY_DEFAULT
+};
+
+const char kFeatureOffByDefaultName[] = "OffByDefault";
+struct Feature kFeatureOffByDefault {
+  kFeatureOffByDefaultName, FEATURE_DISABLED_BY_DEFAULT
+};
+
+}  // namespace
+
+class FeatureListTest : public testing::Test {
+ public:
+  FeatureListTest() : feature_list_(nullptr) {
+    RegisterFeatureListInstance(make_scoped_ptr(new FeatureList));
+  }
+  ~FeatureListTest() override { ClearFeatureListInstance(); }
+
+  void RegisterFeatureListInstance(scoped_ptr<FeatureList> feature_list) {
+    feature_list_ = feature_list.get();
+    FeatureList::SetInstance(feature_list.Pass());
+  }
+  void ClearFeatureListInstance() {
+    FeatureList::ClearInstanceForTesting();
+    feature_list_ = nullptr;
+  }
+
+  FeatureList* feature_list() { return feature_list_; }
+
+ private:
+  // Weak. Owned by the FeatureList::SetInstance().
+  FeatureList* feature_list_;
+
+  DISALLOW_COPY_AND_ASSIGN(FeatureListTest);
+};
+
+TEST_F(FeatureListTest, DefaultStates) {
+  EXPECT_TRUE(FeatureList::IsEnabled(kFeatureOnByDefault));
+  EXPECT_FALSE(FeatureList::IsEnabled(kFeatureOffByDefault));
+}
+
+TEST_F(FeatureListTest, InitializeFromCommandLine) {
+  struct {
+    const char* enable_features;
+    const char* disable_features;
+    bool expected_feature_on_state;
+    bool expected_feature_off_state;
+  } test_cases[] = {
+      {"", "", true, false},
+      {"OffByDefault", "", true, true},
+      {"OffByDefault", "OnByDefault", false, true},
+      {"OnByDefault,OffByDefault", "", true, true},
+      {"", "OnByDefault,OffByDefault", false, false},
+      // In the case an entry is both, disable takes precedence.
+      {"OnByDefault", "OnByDefault,OffByDefault", false, false},
+  };
+
+  for (size_t i = 0; i < arraysize(test_cases); ++i) {
+    const auto& test_case = test_cases[i];
+
+    ClearFeatureListInstance();
+    scoped_ptr<FeatureList> feature_list(new FeatureList);
+    feature_list->InitializeFromCommandLine(test_case.enable_features,
+                                            test_case.disable_features);
+    RegisterFeatureListInstance(feature_list.Pass());
+
+    EXPECT_EQ(test_case.expected_feature_on_state,
+              FeatureList::IsEnabled(kFeatureOnByDefault))
+        << i;
+    EXPECT_EQ(test_case.expected_feature_off_state,
+              FeatureList::IsEnabled(kFeatureOffByDefault))
+        << i;
+  }
+}
+
+TEST_F(FeatureListTest, CheckFeatureIdentity) {
+  // Tests that CheckFeatureIdentity() correctly detects when two different
+  // structs with the same feature name are passed to it.
+
+  // Call it twice for each feature at the top of the file, since the first call
+  // makes it remember the entry and the second call will verify it.
+  EXPECT_TRUE(feature_list()->CheckFeatureIdentity(kFeatureOnByDefault));
+  EXPECT_TRUE(feature_list()->CheckFeatureIdentity(kFeatureOnByDefault));
+  EXPECT_TRUE(feature_list()->CheckFeatureIdentity(kFeatureOffByDefault));
+  EXPECT_TRUE(feature_list()->CheckFeatureIdentity(kFeatureOffByDefault));
+
+  // Now, call it with a distinct struct for |kFeatureOnByDefaultName|, which
+  // should return false.
+  struct Feature kFeatureOnByDefault2 {
+    kFeatureOnByDefaultName, FEATURE_ENABLED_BY_DEFAULT
+  };
+  EXPECT_FALSE(feature_list()->CheckFeatureIdentity(kFeatureOnByDefault2));
+}
+
+}  // namespace base