Add a grisu test stub

src/format.cc

@@ -10,6 +10,10 @@
 FMT_BEGIN_NAMESPACE
 template struct internal::basic_data<void>;
 
+// Workaround a bug in MSVC2013 that prevents instantiation of grisu2_format.
+bool (*instantiate_grisu2_format)(double, internal::buffer&,
+                                  core_format_specs) = internal::grisu2_format;
+
 #ifndef FMT_STATIC_THOUSANDS_SEPARATOR
 template FMT_API internal::locale_ref::locale_ref(const std::locale& loc);
 template FMT_API std::locale internal::locale_ref::get<std::locale>() const;

test/CMakeLists.txt

@@ -87,6 +87,7 @@ endfunction()
 add_fmt_test(assert-test)
 add_fmt_test(chrono-test)
 add_fmt_test(core-test)
+add_fmt_test(grisu-test)
 add_fmt_test(gtest-extra-test)
 add_fmt_test(format-test mock-allocator.h)
 if (NOT (MSVC AND BUILD_SHARED_LIBS))

test/grisu-test.cc

@@ -0,0 +1,29 @@
+// Formatting library for C++ - Grisu tests
+//
+// Copyright (c) 2012 - present, Victor Zverovich
+// All rights reserved.
+//
+// For the license information refer to format.h.
+
+#define FMT_USE_GRISU std::numeric_limits<double>::is_iec559
+#include "fmt/format.h"
+#include "gtest.h"
+
+bool reported_skipped;
+
+#undef TEST
+#define TEST(test_fixture, test_name)        \
+  void test_fixture##test_name();            \
+  GTEST_TEST(test_fixture, test_name) {      \
+    if (FMT_USE_GRISU) {                     \
+      test_fixture##test_name();             \
+    } else if (!reported_skipped) {          \
+      reported_skipped = true;               \
+      fmt::print("Skipping Grisu tests.\n"); \
+    }                                        \
+  }                                          \
+  void test_fixture##test_name()
+
+TEST(GrisuTest, NaN) {
+  EXPECT_EQ("nan", fmt::format("{}", std::numeric_limits<double>::quiet_NaN()));
+}