externals: Add fmt subtree

Merge commit 'a9f62a15cd' as 'externals/fmt'

externals/fmt/test/time-test.cc

@@ -0,0 +1,60 @@
+/*
+ Time formatting tests
+
+ Copyright (c) 2012 - 2016, Victor Zverovich
+ All rights reserved.
+
+ For the license information refer to format.h.
+ */
+#ifdef WIN32
+#define _CRT_SECURE_NO_WARNINGS
+#endif
+
+#include "gmock/gmock.h"
+#include "fmt/time.h"
+
+TEST(TimeTest, Format) {
+  std::tm tm = std::tm();
+  tm.tm_year = 116;
+  tm.tm_mon  = 3;
+  tm.tm_mday = 25;
+  EXPECT_EQ("The date is 2016-04-25.",
+            fmt::format("The date is {:%Y-%m-%d}.", tm));
+}
+
+TEST(TimeTest, GrowBuffer) {
+  std::string s = "{:";
+  for (int i = 0; i < 30; ++i)
+    s += "%c";
+  s += "}\n";
+  std::time_t t = std::time(0);
+  fmt::format(s, *std::localtime(&t));
+}
+
+TEST(TimeTest, EmptyResult) {
+  EXPECT_EQ("", fmt::format("{}", std::tm()));
+}
+
+bool EqualTime(const std::tm &lhs, const std::tm &rhs) {
+  return lhs.tm_sec == rhs.tm_sec &&
+         lhs.tm_min == rhs.tm_min &&
+         lhs.tm_hour == rhs.tm_hour &&
+         lhs.tm_mday == rhs.tm_mday &&
+         lhs.tm_mon == rhs.tm_mon &&
+         lhs.tm_year == rhs.tm_year &&
+         lhs.tm_wday == rhs.tm_wday &&
+         lhs.tm_yday == rhs.tm_yday &&
+         lhs.tm_isdst == rhs.tm_isdst;
+}
+
+TEST(TimeTest, LocalTime) {
+  std::time_t t = std::time(0);
+  std::tm tm = *std::localtime(&t);
+  EXPECT_TRUE(EqualTime(tm, fmt::localtime(t)));
+}
+
+TEST(TimeTest, GMTime) {
+  std::time_t t = std::time(0);
+  std::tm tm = *std::gmtime(&t);
+  EXPECT_TRUE(EqualTime(tm, fmt::gmtime(t)));
+}