Add STLSetDifference to stl_util.h, because std::set_difference is extremely

base/stl_util_unittest.cc

Index: base/stl_util_unittest.cc
diff --git a/base/stl_util_unittest.cc b/base/stl_util_unittest.cc
new file mode 100644
index 0000000000000000000000000000000000000000..63d5c5c1ee7cf21bb5e223c34c61b0a1c06fb6cd
--- /dev/null
+++ b/base/stl_util_unittest.cc
@@ -0,0 +1,82 @@
+// Copyright 2012 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/stl_util.h"
+
+#include <set>
+
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace base {
+namespace {
+
+TEST(STLUtilTest, STLIsSorted) {
+  {
+    std::set<int> set;
+    set.insert(24);
+    set.insert(1);
+    set.insert(12);
+    EXPECT_TRUE(STLIsSorted(set));
+  }
+
+  {
+    std::vector<int> vector;
+    vector.push_back(1);
+    vector.push_back(1);
+    vector.push_back(4);
+    vector.push_back(64);
+    vector.push_back(12432);
+    EXPECT_TRUE(STLIsSorted(vector));
+    vector.back() = 1;
+    EXPECT_FALSE(STLIsSorted(vector));
+  }
+}
+
+TEST(STLUtilTest, STLSetDifference) {
+  std::set<int> a1;
+  a1.insert(1);
+  a1.insert(2);
+  a1.insert(3);
+  a1.insert(4);
+
+  std::set<int> a2;
+  a2.insert(3);
+  a2.insert(4);
+  a2.insert(5);
+  a2.insert(6);
+  a2.insert(7);
+
+  {
+    std::set<int> difference;
+    difference.insert(1);
+    difference.insert(2);
+    EXPECT_EQ(difference, STLSetDifference<std::set<int> >(a1, a2));
+  }
+
+  {
+    std::set<int> difference;
+    difference.insert(5);
+    difference.insert(6);
+    difference.insert(7);
+    EXPECT_EQ(difference, STLSetDifference<std::set<int> >(a2, a1));
+  }
+
+  {
+    std::vector<int> difference;
+    difference.push_back(1);
+    difference.push_back(2);
+    EXPECT_EQ(difference, STLSetDifference<std::vector<int> >(a1, a2));
+  }
+
+  {
+    std::vector<int> difference;
+    difference.push_back(5);
+    difference.push_back(6);
+    difference.push_back(7);
+    EXPECT_EQ(difference, STLSetDifference<std::vector<int> >(a2, a1));
+  }
+}
+
+}  // namespace
+}  // namespace base