Improving flat containers interface.

base/containers/flat_map_unittest.cc

Index: base/containers/flat_map_unittest.cc
diff --git a/base/containers/flat_map_unittest.cc b/base/containers/flat_map_unittest.cc
index 0556527635a69ebe16153cd33134fdefc8e96fe6..3ab9a45ddf41113144adfa0841df6a7b4d723237 100644
--- a/base/containers/flat_map_unittest.cc
+++ b/base/containers/flat_map_unittest.cc
@@ -7,8 +7,8 @@
 #include <string>
 #include <vector>
 
-#include "base/containers/container_test_utils.h"
 #include "base/macros.h"
+#include "base/test/move_only_int.h"
 #include "testing/gmock/include/gmock/gmock.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
@@ -170,4 +170,44 @@ TEST(FlatMap, SubscriptMoveOnlyKey) {
   EXPECT_EQ(44, m[MoveOnlyInt(1)]);
 }
 
+TEST(FlatMap, UsingTransparentCompare) {
+  using ExplicitInt = base::MoveOnlyInt;
+  base::flat_map<ExplicitInt, int> m;
+  const auto& m1 = m;
+  int x = 0;
+
+  // Check if we can use lookup functions without converting to key_type.
+  // Correctness is checked in flat_tree tests.
+  m.count(x);
+  m1.count(x);
+  m.find(x);
+  m1.find(x);
+  m.equal_range(x);
+  m1.equal_range(x);
+  m.lower_bound(x);
+  m1.lower_bound(x);
+  m.upper_bound(x);
+  m1.upper_bound(x);
+  m.erase(x);
+
+  // Check if we broke overload resolution.
+  m.emplace(ExplicitInt(0), 0);
+  m.emplace(ExplicitInt(1), 0);
+  m.erase(m.begin());
+  m.erase(m.cbegin());
+}
+
+TEST(FlatMap, Examples) {
+  base::flat_map<std::string, int> str_to_int({{"a", 1}, {"c", 2}, {"b", 2}},
+                                              base::KEEP_FIRST_OF_DUPES);
+
+  // NOTE: does construct a temporary string.
+  str_to_int["c"] = 3;
+
+  // Do not construct temporary strings.

[danakj, 2017/06/27 23:48:25]

If we're not testing somehow the temp strings are not being constructed, then
these don't belong as unit tests. The examples don't need to be unit tests, we
can leave them in the README.md alone.

[dyaroshev, 2017/06/28 09:13:59]

Done

+  str_to_int.lower_bound("abc")->second = 3;
+  str_to_int.erase("c");
+  EXPECT_EQ(str_to_int.end(), str_to_int.find("c"));
+}
+
 }  // namespace base