// Formatting library for C++ - std::ostream support tests
//
// Copyright (c) 2012 - present, Victor Zverovich
// All rights reserved.
// For the license information refer to format.h.
#define FMT_STRING_ALIAS 1
#include "fmt/format.h"
struct test {};
// Test that there is no issues with specializations when fmt/ostream.h is
// included after fmt/format.h.
namespace fmt {
template <> struct formatter<test> : formatter<int> {
template <typename FormatContext>
typename FormatContext::iterator format(const test&, FormatContext& ctx) {
return formatter<int>::format(42, ctx);
}
};
} // namespace fmt
#include <sstream>
#include "fmt/ostream.h"
#include "gmock.h"
#include "gtest-extra.h"
#include "util.h"
using fmt::format;
using fmt::format_error;
static std::ostream& operator<<(std::ostream& os, const Date& d) {
os << d.year() << '-' << d.month() << '-' << d.day();
return os;
static std::wostream& operator<<(std::wostream& os, const Date& d) {
os << d.year() << L'-' << d.month() << L'-' << d.day();
// Make sure that overloaded comma operators do no harm to is_streamable.
struct type_with_comma_op {};
template <typename T> void operator,(type_with_comma_op, const T&);
template <typename T> type_with_comma_op operator<<(T&, const Date&);
enum streamable_enum {};
static std::ostream& operator<<(std::ostream& os, streamable_enum) {
return os << "streamable_enum";
static std::wostream& operator<<(std::wostream& os, streamable_enum) {
return os << L"streamable_enum";
enum unstreamable_enum {};
TEST(OStreamTest, Enum) {
EXPECT_EQ("streamable_enum", fmt::format("{}", streamable_enum()));
EXPECT_EQ("0", fmt::format("{}", unstreamable_enum()));
EXPECT_EQ(L"streamable_enum", fmt::format(L"{}", streamable_enum()));
EXPECT_EQ(L"0", fmt::format(L"{}", unstreamable_enum()));
struct test_arg_formatter
: fmt::detail::arg_formatter<fmt::format_context::iterator, char> {
fmt::format_parse_context parse_ctx;
test_arg_formatter(fmt::format_context& ctx, fmt::format_specs& s)
: fmt::detail::arg_formatter<fmt::format_context::iterator, char>(
ctx, &parse_ctx, &s),
parse_ctx("") {}
TEST(OStreamTest, CustomArg) {
fmt::memory_buffer buffer;
fmt::detail::buffer<char>& base = buffer;
fmt::format_context ctx(std::back_inserter(base), fmt::format_args());
fmt::format_specs spec;
test_arg_formatter af(ctx, spec);
fmt::visit_format_arg(
af, fmt::detail::make_arg<fmt::format_context>(streamable_enum()));
EXPECT_EQ("streamable_enum", std::string(buffer.data(), buffer.size()));
TEST(OStreamTest, Format) {
EXPECT_EQ("a string", format("{0}", TestString("a string")));
std::string s = format("The date is {0}", Date(2012, 12, 9));
EXPECT_EQ("The date is 2012-12-9", s);
Date date(2012, 12, 9);
EXPECT_EQ(L"The date is 2012-12-9",
format(L"The date is {0}", Date(2012, 12, 9)));
TEST(OStreamTest, FormatSpecs) {
EXPECT_EQ("def ", format("{0:<5}", TestString("def")));
EXPECT_EQ(" def", format("{0:>5}", TestString("def")));
#if FMT_DEPRECATED_NUMERIC_ALIGN
EXPECT_THROW_MSG(format("{0:=5}", TestString("def")), format_error,
"format specifier requires numeric argument");
#endif
EXPECT_EQ(" def ", format("{0:^5}", TestString("def")));
EXPECT_EQ("def**", format("{0:*<5}", TestString("def")));
EXPECT_THROW_MSG(format("{0:+}", TestString()), format_error,
EXPECT_THROW_MSG(format("{0:-}", TestString()), format_error,
EXPECT_THROW_MSG(format("{0: }", TestString()), format_error,
EXPECT_THROW_MSG(format("{0:#}", TestString()), format_error,
EXPECT_THROW_MSG(format("{0:05}", TestString()), format_error,
EXPECT_EQ("test ", format("{0:13}", TestString("test")));
EXPECT_EQ("test ", format("{0:{1}}", TestString("test"), 13));
EXPECT_EQ("te", format("{0:.2}", TestString("test")));
EXPECT_EQ("te", format("{0:.{1}}", TestString("test"), 2));
struct EmptyTest {};
static std::ostream& operator<<(std::ostream& os, EmptyTest) {
return os << "";
TEST(OStreamTest, EmptyCustomOutput) {
EXPECT_EQ("", fmt::format("{}", EmptyTest()));
TEST(OStreamTest, Print) {
std::ostringstream os;
fmt::print(os, "Don't {}!", "panic");
EXPECT_EQ("Don't panic!", os.str());
std::wostringstream wos;
fmt::print(wos, L"Don't {}!", L"panic");
EXPECT_EQ(L"Don't panic!", wos.str());
TEST(OStreamTest, WriteToOStream) {
const char* foo = "foo";
buffer.append(foo, foo + std::strlen(foo));
fmt::detail::write_buffer(os, buffer);
EXPECT_EQ("foo", os.str());
TEST(OStreamTest, WriteToOStreamMaxSize) {
size_t max_size = fmt::detail::max_value<size_t>();
std::streamsize max_streamsize = fmt::detail::max_value<std::streamsize>();
if (max_size <= fmt::detail::to_unsigned(max_streamsize)) return;
struct test_buffer : fmt::detail::buffer<char> {
explicit test_buffer(size_t size) { resize(size); }
void grow(size_t) {}
} buffer(max_size);
struct mock_streambuf : std::streambuf {
MOCK_METHOD2(xsputn, std::streamsize(const void* s, std::streamsize n));
std::streamsize xsputn(const char* s, std::streamsize n) {
const void* v = s;
return xsputn(v, n);
} streambuf;
struct test_ostream : std::ostream {
explicit test_ostream(mock_streambuf& buffer) : std::ostream(&buffer) {}
} os(streambuf);
testing::InSequence sequence;
const char* data = nullptr;
typedef std::make_unsigned<std::streamsize>::type ustreamsize;
ustreamsize size = max_size;
do {
auto n = std::min(size, fmt::detail::to_unsigned(max_streamsize));
EXPECT_CALL(streambuf, xsputn(data, static_cast<std::streamsize>(n)))
.WillOnce(testing::Return(max_streamsize));
data += n;
size -= n;
} while (size != 0);
TEST(OStreamTest, Join) {
int v[3] = {1, 2, 3};
EXPECT_EQ("1, 2, 3", fmt::format("{}", fmt::join(v, v + 3, ", ")));
#if FMT_USE_CONSTEXPR
TEST(OStreamTest, ConstexprString) {
EXPECT_EQ("42", format(FMT_STRING("{}"), std::string("42")));
EXPECT_EQ("a string", format(FMT_STRING("{0}"), TestString("a string")));
namespace fmt_test {
struct ABC {};
template <typename Output> Output& operator<<(Output& out, ABC) {
out << "ABC";
return out;
} // namespace fmt_test
template <typename T> struct TestTemplate {};
template <typename T>
std::ostream& operator<<(std::ostream& os, TestTemplate<T>) {
return os << 1;
template <typename T> struct formatter<TestTemplate<T>> : formatter<int> {
typename FormatContext::iterator format(TestTemplate<T>, FormatContext& ctx) {
return formatter<int>::format(2, ctx);
#if !FMT_GCC_VERSION || FMT_GCC_VERSION >= 407
TEST(OStreamTest, Template) {
EXPECT_EQ("2", fmt::format("{}", TestTemplate<int>()));
TEST(FormatTest, FormatToN) {
char buffer[4];
buffer[3] = 'x';
auto result = fmt::format_to_n(buffer, 3, "{}", fmt_test::ABC());
EXPECT_EQ(3u, result.size);
EXPECT_EQ(buffer + 3, result.out);
EXPECT_EQ("ABCx", fmt::string_view(buffer, 4));
result = fmt::format_to_n(buffer, 3, "x{}y", fmt_test::ABC());
EXPECT_EQ(5u, result.size);
EXPECT_EQ("xABx", fmt::string_view(buffer, 4));
#if FMT_USE_USER_DEFINED_LITERALS
TEST(FormatTest, UDL) {
using namespace fmt::literals;
EXPECT_EQ("{}"_format("test"), "test");
template <typename T> struct convertible {
T value;
explicit convertible(const T& val) : value(val) {}
operator T() const { return value; }
TEST(OStreamTest, DisableBuiltinOStreamOperators) {
EXPECT_EQ("42", fmt::format("{:d}", convertible<unsigned short>(42)));
EXPECT_EQ(L"42", fmt::format(L"{:d}", convertible<unsigned short>(42)));
EXPECT_EQ("foo", fmt::format("{}", convertible<const char*>("foo")));
struct explicitly_convertible_to_string_like {
template <typename String,
typename = typename std::enable_if<std::is_constructible<
String, const char*, size_t>::value>::type>
explicit operator String() const {
return String("foo", 3u);
std::ostream& operator<<(std::ostream& os,
explicitly_convertible_to_string_like) {
return os << "bar";
TEST(OStreamTest, FormatExplicitlyConvertibleToStringLike) {
EXPECT_EQ("bar", fmt::format("{}", explicitly_convertible_to_string_like()));
#ifdef FMT_USE_STRING_VIEW
struct explicitly_convertible_to_std_string_view {
explicit operator fmt::detail::std_string_view<char>() const {
return {"foo", 3u};
explicitly_convertible_to_std_string_view) {
TEST(OStreamTest, FormatExplicitlyConvertibleToStdStringView) {
#endif // FMT_USE_STRING_VIEW
struct copyfmt_test {};
std::ostream& operator<<(std::ostream& os, copyfmt_test) {
std::ios ios(nullptr);
ios.copyfmt(os);
return os << "foo";
TEST(OStreamTest, CopyFmt) {
EXPECT_EQ("foo", fmt::format("{}", copyfmt_test()));
TEST(OStreamTest, CompileTimeString) {
EXPECT_EQ("42", fmt::format(FMT_STRING("{}"), 42));