Improving flat containers interface.

base/functional_unittest.cc

Index: base/functional_unittest.cc
diff --git a/base/functional_unittest.cc b/base/functional_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..0dec075a1ccd70697d9e25229112aba54d59bcbb
--- /dev/null
+++ b/base/functional_unittest.cc
@@ -0,0 +1,26 @@
+// Copyright 2017 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/functional.h"
+
+#include "base/containers/container_test_utils.h"
+#include "base/containers/flat_tree.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+
+namespace {
+
+TEST(Functional, Less) {
+  using ExplicitInt = base::MoveOnlyInt;
+  EXPECT_TRUE(base::less()(ExplicitInt(3), 4));
+  EXPECT_FALSE(base::less()(4, ExplicitInt(3)));
+  EXPECT_TRUE(base::less()(3, 4));
+
+  static_assert(base::internal::IsTransparentCompare<base::less>::value, "");
+}
+
+}  // namespace
+
+}  // namespace base