//===----------------------------------------------------------------------===//
// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
// See https://llvm.org/LICENSE.txt for license information.
// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
//
//===----------------------------------------------------------------------===//

#ifndef TEST_STD_UTILITIES_FORMAT_FORMAT_RANGE_FORMAT_RANGE_FMTSET_FORMAT_FUNCTIONS_TESTS_H
#define TEST_STD_UTILITIES_FORMAT_FORMAT_RANGE_FORMAT_RANGE_FMTSET_FORMAT_FUNCTIONS_TESTS_H

#include <algorithm>
#include <format>
#include <set>
#include <tuple>
#include <unordered_set>
#include <utility>

#include "format.functions.common.h"
#include "make_string.h"
#include "platform_support.h" // locale name macros
#include "test_macros.h"

//
// Char
//

template <class CharT, class TestFunction, class ExceptionTest>
void test_char_default(TestFunction check, ExceptionTest check_exception) {
  std::set input{CharT('a'), CharT('c'), CharT('b')}; // input not sorted.

  // Note when no range-underlying-spec is present the char is escaped,
  check(SV("{'a', 'b', 'c'}"), SV("{}"), input);
  // when one is present there is no escaping,
  check(SV("{a, b, c}"), SV("{::}"), input);
  // unless forced by the type specifier.
  check(SV("{'a', 'b', 'c'}"), SV("{::?}"), input);

  // ***** underlying has no format-spec

  // *** align-fill & width ***
  check(SV("{'a', 'b', 'c'}     "), SV("{:20}"), input);
  check(SV("{'a', 'b', 'c'}*****"), SV("{:*<20}"), input);
  check(SV("__{'a', 'b', 'c'}___"), SV("{:_^20}"), input);
  check(SV("#####{'a', 'b', 'c'}"), SV("{:#>20}"), input);

  check(SV("{'a', 'b', 'c'}     "), SV("{:{}}"), input, 20);
  check(SV("{'a', 'b', 'c'}*****"), SV("{:*<{}}"), input, 20);
  check(SV("__{'a', 'b', 'c'}___"), SV("{:_^{}}"), input, 20);
  check(SV("#####{'a', 'b', 'c'}"), SV("{:#>{}}"), input, 20);

  check_exception("The format-spec range-fill field contains an invalid character", SV("{:}<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{:{<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::<}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:-}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:+}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{: }"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:#}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{:0}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:.}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:L}"), input);

  // *** n
  check(SV("__'a', 'b', 'c'___"), SV("{:_^18n}"), input);

  // *** type ***
  check_exception("The range-format-spec type m requires two elements for a pair or tuple", SV("{:m}"), input);

  // ***** Only underlying has a format-spec
  check(SV("{a   , b   , c   }"), SV("{::4}"), input);
  check(SV("{a***, b***, c***}"), SV("{::*<4}"), input);
  check(SV("{_a__, _b__, _c__}"), SV("{::_^4}"), input);
  check(SV("{:::a, :::b, :::c}"), SV("{:::>4}"), input);

  check(SV("{a   , b   , c   }"), SV("{::{}}"), input, 4);
  check(SV("{a***, b***, c***}"), SV("{::*<{}}"), input, 4);
  check(SV("{_a__, _b__, _c__}"), SV("{::_^{}}"), input, 4);
  check(SV("{:::a, :::b, :::c}"), SV("{:::>{}}"), input, 4);

  check_exception("The format-spec fill field contains an invalid character", SV("{::}<}"), input);
  check_exception("The format-spec fill field contains an invalid character", SV("{::{<}"), input);

  // *** sign ***
  check_exception("A sign field isn't allowed in this format-spec", SV("{::-}"), input);
  check_exception("A sign field isn't allowed in this format-spec", SV("{::+}"), input);
  check_exception("A sign field isn't allowed in this format-spec", SV("{:: }"), input);

  check(SV("{97, 98, 99}"), SV("{::-d}"), input);
  check(SV("{+97, +98, +99}"), SV("{::+d}"), input);
  check(SV("{ 97,  98,  99}"), SV("{:: d}"), input);

  // *** alternate form ***
  check_exception("An alternate form field isn't allowed in this format-spec", SV("{::#}"), input);

  check(SV("{0x61, 0x62, 0x63}"), SV("{::#x}"), input);

  // *** zero-padding ***
  check_exception("A zero-padding field isn't allowed in this format-spec", SV("{::05}"), input);

  check(SV("{00141, 00142, 00143}"), SV("{::05o}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::.}"), input);

  // *** locale-specific form ***
  check(SV("{a, b, c}"), SV("{::L}"), input);

  // *** type ***
  for (std::basic_string_view<CharT> fmt : fmt_invalid_nested_types<CharT>("bBcdoxX?"))
    check_exception("The format-spec type has a type not supported for a char argument", fmt, input);

  // ***** Both have a format-spec
  check(SV("^^{:a, :b, :c}^^^"), SV("{:^^17::>2}"), input);
  check(SV("^^{:a, :b, :c}^^^"), SV("{:^^{}::>2}"), input, 17);
  check(SV("^^{:a, :b, :c}^^^"), SV("{:^^{}::>{}}"), input, 17, 2);

  check_exception("Argument index out of bounds", SV("{:^^{}::>2}"), input);
  check_exception("Argument index out of bounds", SV("{:^^{}::>{}}"), input, 17);
}

// A set can be written as a string, based on
//   [tab:formatter.range.type]
//   s  T shall be charT. ...
// This does not seem very useful, but it is allowed.
template <class CharT, class TestFunction, class ExceptionTest>
void test_char_string(TestFunction check, [[maybe_unused]] ExceptionTest check_exception) {
  std::set input{CharT('a'), CharT('c'), CharT('b')}; // input not sorted.

  check(SV("abc"), SV("{:s}"), input);

  // ***** underlying has no format-spec

  // *** align-fill & width ***
  check(SV("abc   "), SV("{:6s}"), input);
  check(SV("abc***"), SV("{:*<6s}"), input);
  check(SV("_abc__"), SV("{:_^6s}"), input);
  check(SV("###abc"), SV("{:#>6s}"), input);

  check(SV("abc   "), SV("{:{}s}"), input, 6);
  check(SV("abc***"), SV("{:*<{}s}"), input, 6);
  check(SV("_abc__"), SV("{:_^{}s}"), input, 6);
  check(SV("###abc"), SV("{:#>{}s}"), input, 6);

  check_exception("The format-spec range-fill field contains an invalid character", SV("{:}<s}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{:{<s}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::<s}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:-s}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:+s}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{: s}"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:#s}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{:0s}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:.s}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:Ls}"), input);

  // *** n
  check_exception("The n option and type s can't be used together", SV("{:ns}"), input);

  // *** type ***
  check_exception("The range-format-spec type m requires two elements for a pair or tuple", SV("{:m}"), input);

  // ***** Only underlying has a format-spec
  check_exception("Type s and an underlying format specification can't be used together", SV("{:s:}"), input);
  for (std::basic_string_view<CharT> fmt : fmt_invalid_nested_types<CharT>("bBcdoxX?"))
    check_exception("The format-spec type has a type not supported for a char argument", fmt, input);

  // ***** Both have a format-spec
  check_exception("Type s and an underlying format specification can't be used together", SV("{:5s:5}"), input);
}

// A set can be written as a debug_string, based on
//   [tab:formatter.range.type]
//   ?s T shall be charT. ...
// This does not seem very useful, but it is allowed.
template <class CharT, class TestFunction, class ExceptionTest>
void test_char_escaped_string(TestFunction check, [[maybe_unused]] ExceptionTest check_exception) {
  std::set input{CharT('a'), CharT('c'), CharT('b')}; // input not sorted.

  check(SV("\"abc\""), SV("{:?s}"), input);

  // ***** underlying has no format-spec

  // *** align-fill & width ***
  check(SV(R"("abc"   )"), SV("{:8?s}"), input);
  check(SV(R"("abc"***)"), SV("{:*<8?s}"), input);
  check(SV(R"(_"abc"__)"), SV("{:_^8?s}"), input);
  check(SV(R"(###"abc")"), SV("{:#>8?s}"), input);

  check(SV(R"("abc"   )"), SV("{:{}?s}"), input, 8);
  check(SV(R"("abc"***)"), SV("{:*<{}?s}"), input, 8);
  check(SV(R"(_"abc"__)"), SV("{:_^{}?s}"), input, 8);
  check(SV(R"(###"abc")"), SV("{:#>{}?s}"), input, 8);

  check_exception("The format-spec range-fill field contains an invalid character", SV("{:}<?s}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{:{<?s}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::<?s}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:-?s}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:+?s}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{: ?s}"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:#?s}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{:0?s}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:.?s}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:L?s}"), input);

  // *** n
  check_exception("The n option and type ?s can't be used together", SV("{:n?s}"), input);

  // *** type ***
  check_exception("The range-format-spec type m requires two elements for a pair or tuple", SV("{:m}"), input);

  // ***** Only underlying has a format-spec
  check_exception("Type ?s and an underlying format specification can't be used together", SV("{:?s:}"), input);

  // ***** Both have a format-spec
  check_exception("Type ?s and an underlying format specification can't be used together", SV("{:5?s:5}"), input);
}

template <class CharT, class TestFunction, class ExceptionTest>
void test_char(TestFunction check, ExceptionTest check_exception) {
  test_char_default<CharT>(check, check_exception);
  test_char_string<CharT>(check, check_exception);
  test_char_escaped_string<CharT>(check, check_exception);
}

//
// char -> wchar_t
//

#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
template <class TestFunction, class ExceptionTest>
void test_char_to_wchar(TestFunction check, ExceptionTest check_exception) {
  std::set input{'a', 'c', 'b'}; // input not sorted.

  using CharT = wchar_t;

  // Note when no range-underlying-spec is present the char is escaped,
  check(SV("{'a', 'b', 'c'}"), SV("{}"), input);
  // when one is present there is no escaping,
  check(SV("{a, b, c}"), SV("{::}"), input);
  // unless forced by the type specifier.
  check(SV("{'a', 'b', 'c'}"), SV("{::?}"), input);

  // ***** underlying has no format-spec

  // *** align-fill & width ***
  check(SV("{'a', 'b', 'c'}     "), SV("{:20}"), input);
  check(SV("{'a', 'b', 'c'}*****"), SV("{:*<20}"), input);
  check(SV("__{'a', 'b', 'c'}___"), SV("{:_^20}"), input);
  check(SV("#####{'a', 'b', 'c'}"), SV("{:#>20}"), input);

  check(SV("{'a', 'b', 'c'}     "), SV("{:{}}"), input, 20);
  check(SV("{'a', 'b', 'c'}*****"), SV("{:*<{}}"), input, 20);
  check(SV("__{'a', 'b', 'c'}___"), SV("{:_^{}}"), input, 20);
  check(SV("#####{'a', 'b', 'c'}"), SV("{:#>{}}"), input, 20);

  check_exception("The format-spec range-fill field contains an invalid character", SV("{:}<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{:{<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::<}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:-}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:+}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{: }"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:#}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{:0}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:.}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:L}"), input);

  // *** n
  check(SV("__'a', 'b', 'c'___"), SV("{:_^18n}"), input);

  // *** type ***
  check_exception("The range-format-spec type m requires two elements for a pair or tuple", SV("{:m}"), input);

  // ***** Only underlying has a format-spec
  check(SV("{a   , b   , c   }"), SV("{::4}"), input);
  check(SV("{a***, b***, c***}"), SV("{::*<4}"), input);
  check(SV("{_a__, _b__, _c__}"), SV("{::_^4}"), input);
  check(SV("{:::a, :::b, :::c}"), SV("{:::>4}"), input);

  check(SV("{a   , b   , c   }"), SV("{::{}}"), input, 4);
  check(SV("{a***, b***, c***}"), SV("{::*<{}}"), input, 4);
  check(SV("{_a__, _b__, _c__}"), SV("{::_^{}}"), input, 4);
  check(SV("{:::a, :::b, :::c}"), SV("{:::>{}}"), input, 4);

  check_exception("The format-spec fill field contains an invalid character", SV("{::}<}"), input);
  check_exception("The format-spec fill field contains an invalid character", SV("{::{<}"), input);

  // *** sign ***
  check_exception("A sign field isn't allowed in this format-spec", SV("{::-}"), input);
  check_exception("A sign field isn't allowed in this format-spec", SV("{::+}"), input);
  check_exception("A sign field isn't allowed in this format-spec", SV("{:: }"), input);

  check(SV("{97, 98, 99}"), SV("{::-d}"), input);
  check(SV("{+97, +98, +99}"), SV("{::+d}"), input);
  check(SV("{ 97,  98,  99}"), SV("{:: d}"), input);

  // *** alternate form ***
  check_exception("An alternate form field isn't allowed in this format-spec", SV("{::#}"), input);

  check(SV("{0x61, 0x62, 0x63}"), SV("{::#x}"), input);

  // *** zero-padding ***
  check_exception("A zero-padding field isn't allowed in this format-spec", SV("{::05}"), input);

  check(SV("{00141, 00142, 00143}"), SV("{::05o}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::.}"), input);

  // *** locale-specific form ***
  check(SV("{a, b, c}"), SV("{::L}"), input);

  // *** type ***
  for (std::basic_string_view<CharT> fmt : fmt_invalid_nested_types<CharT>("bBcdoxX?"))
    check_exception("The format-spec type has a type not supported for a char argument", fmt, input);

  // ***** Both have a format-spec
  check(SV("^^{:a, :b, :c}^^^"), SV("{:^^17::>2}"), input);
  check(SV("^^{:a, :b, :c}^^^"), SV("{:^^{}::>2}"), input, 17);
  check(SV("^^{:a, :b, :c}^^^"), SV("{:^^{}::>{}}"), input, 17, 2);

  check_exception("Argument index out of bounds", SV("{:^^{}::>2}"), input);
  check_exception("Argument index out of bounds", SV("{:^^{}::>{}}"), input, 17);

  // The types s and ?s may only be used when using range_formatter<T, charT>
  // where the types T and charT are the same. This means this can't be used for
  // range_formatter<wchar_t, char> even when formatter<wchar_t, char> has a
  // debug-enabled specialization.

  using CharT = wchar_t;
  check_exception("The range-format-spec type s requires formatting a character type", SV("{:s}"), input);
  check_exception("The range-format-spec type ?s requires formatting a character type", SV("{:?s}"), input);
}
#endif //  _LIBCPP_HAS_NO_WIDE_CHARACTERS

//
// Bool
//

template <class CharT, class TestFunction, class ExceptionTest>
void test_bool(TestFunction check, ExceptionTest check_exception) {
  std::set input{true, false};

  check(SV("{false, true}"), SV("{}"), input);

  // ***** underlying has no format-spec

  // *** align-fill & width ***
  check(SV("{false, true}     "), SV("{:18}"), input);
  check(SV("{false, true}*****"), SV("{:*<18}"), input);
  check(SV("__{false, true}___"), SV("{:_^18}"), input);
  check(SV("#####{false, true}"), SV("{:#>18}"), input);

  check(SV("{false, true}     "), SV("{:{}}"), input, 18);
  check(SV("{false, true}*****"), SV("{:*<{}}"), input, 18);
  check(SV("__{false, true}___"), SV("{:_^{}}"), input, 18);
  check(SV("#####{false, true}"), SV("{:#>{}}"), input, 18);

  check_exception("The format-spec range-fill field contains an invalid character", SV("{:}<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{:{<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::<}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:-}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:+}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{: }"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:#}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{:0}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:.}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:L}"), input);

  // *** n
  check(SV("__false, true___"), SV("{:_^16n}"), input);

  // *** type ***
  check_exception("The range-format-spec type m requires two elements for a pair or tuple", SV("{:m}"), input);
  check_exception("The range-format-spec type s requires formatting a character type", SV("{:s}"), input);
  check_exception("The range-format-spec type ?s requires formatting a character type", SV("{:?s}"), input);

  for (std::basic_string_view<CharT> fmt : fmt_invalid_types<CharT>("s"))
    check_exception("The format-spec should consume the input or end with a '}'", fmt, input);

  // ***** Only underlying has a format-spec
  check(SV("{false  , true   }"), SV("{::7}"), input);
  check(SV("{false**, true***}"), SV("{::*<7}"), input);
  check(SV("{_false_, _true__}"), SV("{::_^7}"), input);
  check(SV("{::false, :::true}"), SV("{:::>7}"), input);

  check(SV("{false  , true   }"), SV("{::{}}"), input, 7);
  check(SV("{false**, true***}"), SV("{::*<{}}"), input, 7);
  check(SV("{_false_, _true__}"), SV("{::_^{}}"), input, 7);
  check(SV("{::false, :::true}"), SV("{:::>{}}"), input, 7);

  check_exception("The format-spec fill field contains an invalid character", SV("{::}<}"), input);
  check_exception("The format-spec fill field contains an invalid character", SV("{::{<}"), input);

  // *** sign ***
  check_exception("A sign field isn't allowed in this format-spec", SV("{::-}"), input);
  check_exception("A sign field isn't allowed in this format-spec", SV("{::+}"), input);
  check_exception("A sign field isn't allowed in this format-spec", SV("{:: }"), input);

  check(SV("{0, 1}"), SV("{::-d}"), input);
  check(SV("{+0, +1}"), SV("{::+d}"), input);
  check(SV("{ 0,  1}"), SV("{:: d}"), input);

  // *** alternate form ***
  check_exception("An alternate form field isn't allowed in this format-spec", SV("{::#}"), input);

  check(SV("{0x0, 0x1}"), SV("{::#x}"), input);

  // *** zero-padding ***
  check_exception("A zero-padding field isn't allowed in this format-spec", SV("{::05}"), input);

  check(SV("{00000, 00001}"), SV("{::05o}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::.}"), input);

  // *** locale-specific form ***
  check(SV("{false, true}"), SV("{::L}"), input);

  // *** type ***
  for (std::basic_string_view<CharT> fmt : fmt_invalid_nested_types<CharT>("bBdosxX"))
    check_exception("The format-spec type has a type not supported for a bool argument", fmt, input);

  // ***** Both have a format-spec
  check(SV("^^{::false, :::true}^^^"), SV("{:^^23::>7}"), input);
  check(SV("^^{::false, :::true}^^^"), SV("{:^^{}::>7}"), input, 23);
  check(SV("^^{::false, :::true}^^^"), SV("{:^^{}::>{}}"), input, 23, 7);

  check_exception("Argument index out of bounds", SV("{:^^{}::>5}"), input);
  check_exception("Argument index out of bounds", SV("{:^^{}::>{}}"), input, 23);
}

template <class CharT, class TestFunction, class ExceptionTest>
void test_bool_multiset(TestFunction check, ExceptionTest check_exception) {
  std::multiset<bool, std::greater<bool>> input{true, false, true}; // unordered

  check(SV("{true, true, false}"), SV("{}"), input);

  // ***** underlying has no format-spec

  // *** align-fill & width ***
  check(SV("{true, true, false}     "), SV("{:24}"), input);
  check(SV("{true, true, false}*****"), SV("{:*<24}"), input);
  check(SV("__{true, true, false}___"), SV("{:_^24}"), input);
  check(SV("#####{true, true, false}"), SV("{:#>24}"), input);

  check(SV("{true, true, false}     "), SV("{:{}}"), input, 24);
  check(SV("{true, true, false}*****"), SV("{:*<{}}"), input, 24);
  check(SV("__{true, true, false}___"), SV("{:_^{}}"), input, 24);
  check(SV("#####{true, true, false}"), SV("{:#>{}}"), input, 24);

  check_exception("The format-spec range-fill field contains an invalid character", SV("{:}<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{:{<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::<}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:-}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:+}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{: }"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:#}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{:0}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:.}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:L}"), input);

  // *** n
  check(SV("__true, true, false___"), SV("{:_^22n}"), input);

  // *** type ***
  check_exception("The range-format-spec type m requires two elements for a pair or tuple", SV("{:m}"), input);
  check_exception("The range-format-spec type s requires formatting a character type", SV("{:s}"), input);
  check_exception("The range-format-spec type ?s requires formatting a character type", SV("{:?s}"), input);

  for (std::basic_string_view<CharT> fmt : fmt_invalid_types<CharT>("s"))
    check_exception("The format-spec should consume the input or end with a '}'", fmt, input);

  // ***** Only underlying has a format-spec
  check(SV("{true   , true   , false  }"), SV("{::7}"), input);
  check(SV("{true***, true***, false**}"), SV("{::*<7}"), input);
  check(SV("{_true__, _true__, _false_}"), SV("{::_^7}"), input);
  check(SV("{:::true, :::true, ::false}"), SV("{:::>7}"), input);

  check(SV("{true   , true   , false  }"), SV("{::{}}"), input, 7);
  check(SV("{true***, true***, false**}"), SV("{::*<{}}"), input, 7);
  check(SV("{_true__, _true__, _false_}"), SV("{::_^{}}"), input, 7);
  check(SV("{:::true, :::true, ::false}"), SV("{:::>{}}"), input, 7);

  check_exception("The format-spec fill field contains an invalid character", SV("{::}<}"), input);
  check_exception("The format-spec fill field contains an invalid character", SV("{::{<}"), input);

  // *** sign ***
  check_exception("A sign field isn't allowed in this format-spec", SV("{::-}"), input);
  check_exception("A sign field isn't allowed in this format-spec", SV("{::+}"), input);
  check_exception("A sign field isn't allowed in this format-spec", SV("{:: }"), input);

  check(SV("{1, 1, 0}"), SV("{::-d}"), input);
  check(SV("{+1, +1, +0}"), SV("{::+d}"), input);
  check(SV("{ 1,  1,  0}"), SV("{:: d}"), input);

  // *** alternate form ***
  check_exception("An alternate form field isn't allowed in this format-spec", SV("{::#}"), input);

  check(SV("{0x1, 0x1, 0x0}"), SV("{::#x}"), input);

  // *** zero-padding ***
  check_exception("A zero-padding field isn't allowed in this format-spec", SV("{::05}"), input);

  check(SV("{00001, 00001, 00000}"), SV("{::05o}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::.}"), input);

  // *** locale-specific form ***
  check(SV("{true, true, false}"), SV("{::L}"), input);

  // *** type ***
  for (std::basic_string_view<CharT> fmt : fmt_invalid_nested_types<CharT>("bBdosxX"))
    check_exception("The format-spec type has a type not supported for a bool argument", fmt, input);

  // ***** Both have a format-spec
  check(SV("^^{:::true, :::true, ::false}^^^"), SV("{:^^32::>7}"), input);
  check(SV("^^{:::true, :::true, ::false}^^^"), SV("{:^^{}::>7}"), input, 32);
  check(SV("^^{:::true, :::true, ::false}^^^"), SV("{:^^{}::>{}}"), input, 32, 7);

  check_exception("Argument index out of bounds", SV("{:^^{}::>5}"), input);
  check_exception("Argument index out of bounds", SV("{:^^{}::>{}}"), input, 32);
}

//
// Integral
//

template <class CharT, class TestFunction, class ExceptionTest>
void test_int(TestFunction check, ExceptionTest check_exception, auto&& input) {
  check(SV("{-42, 1, 2, 42}"), SV("{}"), input);

  // ***** underlying has no format-spec

  // *** align-fill & width ***
  check(SV("{-42, 1, 2, 42}     "), SV("{:20}"), input);
  check(SV("{-42, 1, 2, 42}*****"), SV("{:*<20}"), input);
  check(SV("__{-42, 1, 2, 42}___"), SV("{:_^20}"), input);
  check(SV("#####{-42, 1, 2, 42}"), SV("{:#>20}"), input);

  check(SV("{-42, 1, 2, 42}     "), SV("{:{}}"), input, 20);
  check(SV("{-42, 1, 2, 42}*****"), SV("{:*<{}}"), input, 20);
  check(SV("__{-42, 1, 2, 42}___"), SV("{:_^{}}"), input, 20);
  check(SV("#####{-42, 1, 2, 42}"), SV("{:#>{}}"), input, 20);

  check_exception("The format-spec range-fill field contains an invalid character", SV("{:}<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{:{<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::<}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:-}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:+}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{: }"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:#}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{:0}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:.}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:L}"), input);

  // *** n
  check(SV("__-42, 1, 2, 42___"), SV("{:_^18n}"), input);

  // *** type ***
  check_exception("The range-format-spec type m requires two elements for a pair or tuple", SV("{:m}"), input);
  check_exception("The range-format-spec type s requires formatting a character type", SV("{:s}"), input);
  check_exception("The range-format-spec type ?s requires formatting a character type", SV("{:?s}"), input);

  for (std::basic_string_view<CharT> fmt : fmt_invalid_types<CharT>("s"))
    check_exception("The format-spec should consume the input or end with a '}'", fmt, input);

  // ***** Only underlying has a format-spec
  check(SV("{  -42,     1,     2,    42}"), SV("{::5}"), input);
  check(SV("{-42**, 1****, 2****, 42***}"), SV("{::*<5}"), input);
  check(SV("{_-42_, __1__, __2__, _42__}"), SV("{::_^5}"), input);
  check(SV("{::-42, ::::1, ::::2, :::42}"), SV("{:::>5}"), input);

  check(SV("{  -42,     1,     2,    42}"), SV("{::{}}"), input, 5);
  check(SV("{-42**, 1****, 2****, 42***}"), SV("{::*<{}}"), input, 5);
  check(SV("{_-42_, __1__, __2__, _42__}"), SV("{::_^{}}"), input, 5);
  check(SV("{::-42, ::::1, ::::2, :::42}"), SV("{:::>{}}"), input, 5);

  check_exception("The format-spec fill field contains an invalid character", SV("{::}<}"), input);
  check_exception("The format-spec fill field contains an invalid character", SV("{::{<}"), input);

  // *** sign ***
  check(SV("{-42, 1, 2, 42}"), SV("{::-}"), input);
  check(SV("{-42, +1, +2, +42}"), SV("{::+}"), input);
  check(SV("{-42,  1,  2,  42}"), SV("{:: }"), input);

  // *** alternate form ***
  check(SV("{-0x2a, 0x1, 0x2, 0x2a}"), SV("{::#x}"), input);

  // *** zero-padding ***
  check(SV("{-0042, 00001, 00002, 00042}"), SV("{::05}"), input);
  check(SV("{-002a, 00001, 00002, 0002a}"), SV("{::05x}"), input);
  check(SV("{-0x2a, 0x001, 0x002, 0x02a}"), SV("{::#05x}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::.}"), input);

  // *** locale-specific form ***
  check(SV("{-42, 1, 2, 42}"), SV("{::L}"), input); // does nothing in this test, but is accepted.

  // *** type ***
  for (std::basic_string_view<CharT> fmt : fmt_invalid_nested_types<CharT>("bBcdoxX"))
    check_exception("The format-spec type has a type not supported for an integer argument", fmt, input);

  // ***** Both have a format-spec
  check(SV("^^{::-42, ::::1, ::::2, :::42}^^^"), SV("{:^^33::>5}"), input);
  check(SV("^^{::-42, ::::1, ::::2, :::42}^^^"), SV("{:^^{}::>5}"), input, 33);
  check(SV("^^{::-42, ::::1, ::::2, :::42}^^^"), SV("{:^^{}::>{}}"), input, 33, 5);

  check_exception("Argument index out of bounds", SV("{:^^{}::>5}"), input);
  check_exception("Argument index out of bounds", SV("{:^^{}::>{}}"), input, 33);
}

template <class CharT, class TestFunction, class ExceptionTest>
void test_int(TestFunction check, ExceptionTest check_exception) {
  test_int<CharT>(check, check_exception, std::set{1, 42, 2, -42});      // unsorted
  test_int<CharT>(check, check_exception, std::multiset{1, 42, 2, -42}); // unsorted
}

//
// Floating point
//

template <class CharT, class TestFunction, class ExceptionTest>
void test_floating_point(TestFunction check, ExceptionTest check_exception, auto&& input) {
  check(SV("{-42.5, 0, 1.25, 42.5}"), SV("{}"), input);

  // ***** underlying has no format-spec

  // *** align-fill & width ***
  check(SV("{-42.5, 0, 1.25, 42.5}     "), SV("{:27}"), input);
  check(SV("{-42.5, 0, 1.25, 42.5}*****"), SV("{:*<27}"), input);
  check(SV("__{-42.5, 0, 1.25, 42.5}___"), SV("{:_^27}"), input);
  check(SV("#####{-42.5, 0, 1.25, 42.5}"), SV("{:#>27}"), input);

  check(SV("{-42.5, 0, 1.25, 42.5}     "), SV("{:{}}"), input, 27);
  check(SV("{-42.5, 0, 1.25, 42.5}*****"), SV("{:*<{}}"), input, 27);
  check(SV("__{-42.5, 0, 1.25, 42.5}___"), SV("{:_^{}}"), input, 27);
  check(SV("#####{-42.5, 0, 1.25, 42.5}"), SV("{:#>{}}"), input, 27);

  check_exception("The format-spec range-fill field contains an invalid character", SV("{:}<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{:{<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::<}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:-}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:+}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{: }"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:#}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{:0}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:.}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:L}"), input);

  // *** n
  check(SV("__-42.5, 0, 1.25, 42.5___"), SV("{:_^25n}"), input);

  // *** type ***
  check_exception("The range-format-spec type m requires two elements for a pair or tuple", SV("{:m}"), input);
  check_exception("The range-format-spec type s requires formatting a character type", SV("{:s}"), input);
  check_exception("The range-format-spec type ?s requires formatting a character type", SV("{:?s}"), input);

  for (std::basic_string_view<CharT> fmt : fmt_invalid_types<CharT>("s"))
    check_exception("The format-spec should consume the input or end with a '}'", fmt, input);

  // ***** Only underlying has a format-spec
  check(SV("{-42.5,     0,  1.25,  42.5}"), SV("{::5}"), input);
  check(SV("{-42.5, 0****, 1.25*, 42.5*}"), SV("{::*<5}"), input);
  check(SV("{-42.5, __0__, 1.25_, 42.5_}"), SV("{::_^5}"), input);
  check(SV("{-42.5, ::::0, :1.25, :42.5}"), SV("{:::>5}"), input);

  check(SV("{-42.5,     0,  1.25,  42.5}"), SV("{::{}}"), input, 5);
  check(SV("{-42.5, 0****, 1.25*, 42.5*}"), SV("{::*<{}}"), input, 5);
  check(SV("{-42.5, __0__, 1.25_, 42.5_}"), SV("{::_^{}}"), input, 5);
  check(SV("{-42.5, ::::0, :1.25, :42.5}"), SV("{:::>{}}"), input, 5);

  check_exception("The format-spec fill field contains an invalid character", SV("{::}<}"), input);
  check_exception("The format-spec fill field contains an invalid character", SV("{::{<}"), input);

  // *** sign ***
  check(SV("{-42.5, 0, 1.25, 42.5}"), SV("{::-}"), input);
  check(SV("{-42.5, +0, +1.25, +42.5}"), SV("{::+}"), input);
  check(SV("{-42.5,  0,  1.25,  42.5}"), SV("{:: }"), input);

  // *** alternate form ***
  check(SV("{-42.5, 0., 1.25, 42.5}"), SV("{::#}"), input);

  // *** zero-padding ***
  check(SV("{-42.5, 00000, 01.25, 042.5}"), SV("{::05}"), input);
  check(SV("{-42.5, 0000., 01.25, 042.5}"), SV("{::#05}"), input);

  // *** precision ***
  check(SV("{-42, 0, 1.2, 42}"), SV("{::.2}"), input);
  check(SV("{-42.500, 0.000, 1.250, 42.500}"), SV("{::.3f}"), input);

  check(SV("{-42, 0, 1.2, 42}"), SV("{::.{}}"), input, 2);
  check(SV("{-42.500, 0.000, 1.250, 42.500}"), SV("{::.{}f}"), input, 3);

  check_exception("The format-spec precision field doesn't contain a value or arg-id", SV("{::.}"), input);

  // *** locale-specific form ***
  check(SV("{-42.5, 0, 1.25, 42.5}"), SV("{::L}"), input); // does not require locales present
#ifndef TEST_HAS_NO_LOCALIZATION
// TODO FMT Enable with locale testing active
#  if 0
  std::locale::global(std::locale(LOCALE_fr_FR_UTF_8));
  check(SV("{-42,5, 0, 1,25, 42,5}"), SV("{::L}"), input);

  std::locale::global(std::locale(LOCALE_en_US_UTF_8));
  check(SV("{-42.5, 0, 1.25, 42.5}"), SV("{::L}"), input);

  std::locale::global(std::locale::classic());
#  endif
#endif // TEST_HAS_NO_LOCALIZATION

  // *** type ***
  for (std::basic_string_view<CharT> fmt : fmt_invalid_nested_types<CharT>("aAeEfFgG"))
    check_exception("The format-spec type has a type not supported for a floating-point argument", fmt, input);

  // ***** Both have a format-spec
  check(SV("^^{-42.5, ::::0, :1.25, :42.5}^^^"), SV("{:^^33::>5}"), input);
  check(SV("^^{-42.5, ::::0, :1.25, :42.5}^^^"), SV("{:^^{}::>5}"), input, 33);
  check(SV("^^{-42.5, ::::0, :1.25, :42.5}^^^"), SV("{:^^{}::>{}}"), input, 33, 5);

  check(SV("^^{::-42, ::::0, ::1.2, :::42}^^^"), SV("{:^^33::>5.2}"), input);
  check(SV("^^{::-42, ::::0, ::1.2, :::42}^^^"), SV("{:^^{}::>5.2}"), input, 33);
  check(SV("^^{::-42, ::::0, ::1.2, :::42}^^^"), SV("{:^^{}::>{}.2}"), input, 33, 5);
  check(SV("^^{::-42, ::::0, ::1.2, :::42}^^^"), SV("{:^^{}::>{}.{}}"), input, 33, 5, 2);

  check_exception("Argument index out of bounds", SV("{:^^{}::>5.2}"), input);
  check_exception("Argument index out of bounds", SV("{:^^{}::>{}.2}"), input, 33);
  check_exception("Argument index out of bounds", SV("{:^^{}::>{}.{}}"), input, 33, 5);
}

template <class CharT, class TestFunction, class ExceptionTest>
void test_floating_point(TestFunction check, ExceptionTest check_exception) {
  test_floating_point<CharT>(check, check_exception, std::set{-42.5f, 0.0f, 1.25f, 42.5f});
  test_floating_point<CharT>(check, check_exception, std::multiset{-42.5, 0.0, 1.25, 42.5});
  test_floating_point<CharT>(check, check_exception, std::set{-42.5l, 0.0l, 1.25l, 42.5l});
}

//
// Pointer
//

template <class CharT, class TestFunction, class ExceptionTest>
void test_pointer(TestFunction check, ExceptionTest check_exception, auto&& input) {
  check(SV("{0x0}"), SV("{}"), input);

  // ***** underlying has no format-spec

  // *** align-fill & width ***
  check(SV("{0x0}     "), SV("{:10}"), input);
  check(SV("{0x0}*****"), SV("{:*<10}"), input);
  check(SV("__{0x0}___"), SV("{:_^10}"), input);
  check(SV("#####{0x0}"), SV("{:#>10}"), input);

  check(SV("{0x0}     "), SV("{:{}}"), input, 10);
  check(SV("{0x0}*****"), SV("{:*<{}}"), input, 10);
  check(SV("__{0x0}___"), SV("{:_^{}}"), input, 10);
  check(SV("#####{0x0}"), SV("{:#>{}}"), input, 10);

  check_exception("The format-spec range-fill field contains an invalid character", SV("{:}<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{:{<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::<}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:#}"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:#}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{:0}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:.}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:L}"), input);

  // *** n
  check(SV("_0x0_"), SV("{:_^5n}"), input);

  // *** type ***
  check_exception("The range-format-spec type m requires two elements for a pair or tuple", SV("{:m}"), input);
  check_exception("The range-format-spec type s requires formatting a character type", SV("{:s}"), input);
  check_exception("The range-format-spec type ?s requires formatting a character type", SV("{:?s}"), input);

  for (std::basic_string_view<CharT> fmt : fmt_invalid_types<CharT>("s"))
    check_exception("The format-spec should consume the input or end with a '}'", fmt, input);

  // ***** Only underlying has a format-spec
  check(SV("{  0x0}"), SV("{::5}"), input);
  check(SV("{0x0**}"), SV("{::*<5}"), input);
  check(SV("{_0x0_}"), SV("{::_^5}"), input);
  check(SV("{::0x0}"), SV("{:::>5}"), input);

  check(SV("{  0x0}"), SV("{::{}}"), input, 5);
  check(SV("{0x0**}"), SV("{::*<{}}"), input, 5);
  check(SV("{_0x0_}"), SV("{::_^{}}"), input, 5);
  check(SV("{::0x0}"), SV("{:::>{}}"), input, 5);

  check_exception("The format-spec fill field contains an invalid character", SV("{::}<}"), input);
  check_exception("The format-spec fill field contains an invalid character", SV("{::{<}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::-}"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::#}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{::05}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::.}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::L}"), input);

  // *** type ***
  for (std::basic_string_view<CharT> fmt : fmt_invalid_nested_types<CharT>("p"))
    check_exception("The format-spec type has a type not supported for a pointer argument", fmt, input);

  // ***** Both have a format-spec
  check(SV("^^{::0x0}^^^"), SV("{:^^12::>5}"), input);
  check(SV("^^{::0x0}^^^"), SV("{:^^{}::>5}"), input, 12);
  check(SV("^^{::0x0}^^^"), SV("{:^^{}::>{}}"), input, 12, 5);

  check(SV("^^{::0x0}^^^"), SV("{:^^12::>5}"), input);
  check(SV("^^{::0x0}^^^"), SV("{:^^{}::>5}"), input, 12);
  check(SV("^^{::0x0}^^^"), SV("{:^^{}::>{}}"), input, 12, 5);

  check_exception("Argument index out of bounds", SV("{:^^{}::>5}"), input);
  check_exception("Argument index out of bounds", SV("{:^^{}::>{}}"), input, 12);
}

template <class CharT, class TestFunction, class ExceptionTest>
void test_pointer(TestFunction check, ExceptionTest check_exception) {
  // Note nullptr_t can only be equality compared so not used in a set.
  test_pointer<CharT>(check, check_exception, std::unordered_set{static_cast<const void*>(0)});
  test_pointer<CharT>(check, check_exception, std::unordered_multiset{static_cast<void*>(0)});
}

//
// String
//

template <class CharT, class TestFunction, class ExceptionTest>
void test_string(TestFunction check, ExceptionTest check_exception, auto&& input) {
  check(SV(R"({"Hello", "world"})"), SV("{}"), input);

  // ***** underlying has no format-spec

  // *** align-fill & width ***
  check(SV(R"({"Hello", "world"}     )"), SV("{:23}"), input);
  check(SV(R"({"Hello", "world"}*****)"), SV("{:*<23}"), input);
  check(SV(R"(__{"Hello", "world"}___)"), SV("{:_^23}"), input);
  check(SV(R"(#####{"Hello", "world"})"), SV("{:#>23}"), input);

  check(SV(R"({"Hello", "world"}     )"), SV("{:{}}"), input, 23);
  check(SV(R"({"Hello", "world"}*****)"), SV("{:*<{}}"), input, 23);
  check(SV(R"(__{"Hello", "world"}___)"), SV("{:_^{}}"), input, 23);
  check(SV(R"(#####{"Hello", "world"})"), SV("{:#>{}}"), input, 23);

  check_exception("The format-spec range-fill field contains an invalid character", SV("{:}<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{:{<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::<}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:#}"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:#}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{:0}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:.}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:L}"), input);

  // *** n
  check(SV(R"(_"Hello", "world"_)"), SV("{:_^18n}"), input);

  // *** type ***
  check_exception("The range-format-spec type m requires two elements for a pair or tuple", SV("{:m}"), input);
  check_exception("The range-format-spec type s requires formatting a character type", SV("{:s}"), input);
  check_exception("The range-format-spec type ?s requires formatting a character type", SV("{:?s}"), input);

  for (std::basic_string_view<CharT> fmt : fmt_invalid_types<CharT>("s"))
    check_exception("The format-spec should consume the input or end with a '}'", fmt, input);

  // ***** Only underlying has a format-spec
  check(SV(R"({Hello   , world   })"), SV("{::8}"), input);
  check(SV(R"({Hello***, world***})"), SV("{::*<8}"), input);
  check(SV(R"({_Hello__, _world__})"), SV("{::_^8}"), input);
  check(SV(R"({:::Hello, :::world})"), SV("{:::>8}"), input);

  check(SV(R"({Hello   , world   })"), SV("{::{}}"), input, 8);
  check(SV(R"({Hello***, world***})"), SV("{::*<{}}"), input, 8);
  check(SV(R"({_Hello__, _world__})"), SV("{::_^{}}"), input, 8);
  check(SV(R"({:::Hello, :::world})"), SV("{:::>{}}"), input, 8);

  check_exception("The format-spec fill field contains an invalid character", SV("{::}<}"), input);
  check_exception("The format-spec fill field contains an invalid character", SV("{::{<}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::-}"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::#}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{::05}"), input);

  // *** precision ***
  check(SV(R"({Hel, wor})"), SV("{::.3}"), input);

  check(SV(R"({Hel, wor})"), SV("{::.{}}"), input, 3);

  check_exception("The format-spec precision field doesn't contain a value or arg-id", SV("{::.}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::L}"), input);

  // *** type ***
  for (std::basic_string_view<CharT> fmt : fmt_invalid_nested_types<CharT>("s?"))
    check_exception("The format-spec type has a type not supported for a string argument", fmt, input);

  // ***** Both have a format-spec
  check(SV(R"(^^{:::Hello, :::world}^^^)"), SV("{:^^25::>8}"), input);
  check(SV(R"(^^{:::Hello, :::world}^^^)"), SV("{:^^{}::>8}"), input, 25);
  check(SV(R"(^^{:::Hello, :::world}^^^)"), SV("{:^^{}::>{}}"), input, 25, 8);

  check(SV(R"(^^{:::Hello, :::world}^^^)"), SV("{:^^25::>8}"), input);
  check(SV(R"(^^{:::Hello, :::world}^^^)"), SV("{:^^{}::>8}"), input, 25);
  check(SV(R"(^^{:::Hello, :::world}^^^)"), SV("{:^^{}::>{}}"), input, 25, 8);

  check_exception("Argument index out of bounds", SV("{:^^{}::>8}"), input);
  check_exception("Argument index out of bounds", SV("{:^^{}::>{}}"), input, 25);
}

template <class CharT, class TestFunction, class ExceptionTest>
void test_string(TestFunction check, ExceptionTest check_exception) {
  test_string<CharT>(check, check_exception, std::set{STR("Hello"), STR("world")});
  test_string<CharT>(check, check_exception, std::set{SV("Hello"), SV("world")});
}

//
// Handle
//

template <class CharT, class TestFunction, class ExceptionTest>
void test_status(TestFunction check, ExceptionTest check_exception) {
  std::set input{status::foo, status::bar, status::foobar}; // unordered input

  check(SV("{0x5555, 0xaa55, 0xaaaa}"), SV("{}"), input);

  // ***** underlying has no format-spec

  // *** align-fill & width ***
  check(SV("{0x5555, 0xaa55, 0xaaaa}     "), SV("{:29}"), input);
  check(SV("{0x5555, 0xaa55, 0xaaaa}*****"), SV("{:*<29}"), input);
  check(SV("__{0x5555, 0xaa55, 0xaaaa}___"), SV("{:_^29}"), input);
  check(SV("#####{0x5555, 0xaa55, 0xaaaa}"), SV("{:#>29}"), input);

  check(SV("{0x5555, 0xaa55, 0xaaaa}     "), SV("{:{}}"), input, 29);
  check(SV("{0x5555, 0xaa55, 0xaaaa}*****"), SV("{:*<{}}"), input, 29);
  check(SV("__{0x5555, 0xaa55, 0xaaaa}___"), SV("{:_^{}}"), input, 29);
  check(SV("#####{0x5555, 0xaa55, 0xaaaa}"), SV("{:#>{}}"), input, 29);

  check_exception("The format-spec range-fill field contains an invalid character", SV("{:}<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{:{<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::<}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:-}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:+}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{: }"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:#}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{:0}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:.}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:L}"), input);

  // *** n
  check(SV("__0x5555, 0xaa55, 0xaaaa___"), SV("{:_^27n}"), input);

  // *** type ***
  check_exception("The range-format-spec type m requires two elements for a pair or tuple", SV("{:m}"), input);
  check_exception("The range-format-spec type s requires formatting a character type", SV("{:s}"), input);
  check_exception("The range-format-spec type ?s requires formatting a character type", SV("{:?s}"), input);

  for (std::basic_string_view<CharT> fmt : fmt_invalid_types<CharT>("s"))
    check_exception("The format-spec should consume the input or end with a '}'", fmt, input);

  // ***** Only underlying has a format-spec
  check_exception("The format-spec type has a type not supported for a status argument", SV("{::*<7}"), input);

  check(SV("{0x5555, 0xaa55, 0xaaaa}"), SV("{::x}"), input);
  check(SV("{0X5555, 0XAA55, 0XAAAA}"), SV("{::X}"), input);
  check(SV("{bar, foobar, foo}"), SV("{::s}"), input);

  // ***** Both have a format-spec
  check(SV("^^{0X5555, 0XAA55, 0XAAAA}^^^"), SV("{:^^29:X}"), input);
  check(SV("^^{0X5555, 0XAA55, 0XAAAA}^^^"), SV("{:^^{}:X}"), input, 29);

  check_exception("Argument index out of bounds", SV("{:^^{}:X}"), input);
}

//
// Pair
//

template <class CharT, class TestFunction, class ExceptionTest>
void test_pair_tuple(TestFunction check, ExceptionTest check_exception, auto&& input) {
  check(SV("{(1, a), (42, *)}"), SV("{}"), input);

  // ***** underlying has no format-spec

  // *** align-fill & width ***
  check(SV("{(1, a), (42, *)}     "), SV("{:22}"), input);
  check(SV("{(1, a), (42, *)}*****"), SV("{:*<22}"), input);
  check(SV("__{(1, a), (42, *)}___"), SV("{:_^22}"), input);
  check(SV("#####{(1, a), (42, *)}"), SV("{:#>22}"), input);

  check(SV("{(1, a), (42, *)}     "), SV("{:{}}"), input, 22);
  check(SV("{(1, a), (42, *)}*****"), SV("{:*<{}}"), input, 22);
  check(SV("__{(1, a), (42, *)}___"), SV("{:_^{}}"), input, 22);
  check(SV("#####{(1, a), (42, *)}"), SV("{:#>{}}"), input, 22);

  check_exception("The format-spec range-fill field contains an invalid character", SV("{:}<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{:{<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::<}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:-}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:+}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{: }"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:#}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{:0}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:.}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:L}"), input);

  // *** n
  check(SV("__(1, a), (42, *)___"), SV("{:_^20n}"), input);
  check(SV("__(1, a), (42, *)___"), SV("{:_^20nm}"), input); // m should have no effect

  // *** type ***
  check(SV("__{(1, a), (42, *)}___"), SV("{:_^22m}"), input);
  check_exception("The range-format-spec type s requires formatting a character type", SV("{:s}"), input);
  check_exception("The range-format-spec type ?s requires formatting a character type", SV("{:?s}"), input);

  for (std::basic_string_view<CharT> fmt : fmt_invalid_types<CharT>("s"))
    check_exception("The format-spec should consume the input or end with a '}'", fmt, input);

  // ***** Only underlying has a format-spec
  check(SV("{(1, 'a')   , (42, '*')  }"), SV("{::11}"), input);
  check(SV("{(1, 'a')***, (42, '*')**}"), SV("{::*<11}"), input);
  check(SV("{_(1, 'a')__, _(42, '*')_}"), SV("{::_^11}"), input);
  check(SV("{###(1, 'a'), ##(42, '*')}"), SV("{::#>11}"), input);

  check(SV("{(1, 'a')   , (42, '*')  }"), SV("{::{}}"), input, 11);
  check(SV("{(1, 'a')***, (42, '*')**}"), SV("{::*<{}}"), input, 11);
  check(SV("{_(1, 'a')__, _(42, '*')_}"), SV("{::_^{}}"), input, 11);
  check(SV("{###(1, 'a'), ##(42, '*')}"), SV("{::#>{}}"), input, 11);

  check_exception("The format-spec range-fill field contains an invalid character", SV("{:::<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::}<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::{<}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::-}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::+}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:: }"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::#}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{::05}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::.}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::L}"), input);

  // *** type ***
  check(SV("{1: 'a', 42: '*'}"), SV("{::m}"), input);
  check(SV("{1, 'a', 42, '*'}"), SV("{::n}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::s}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::?s}"), input);

  for (std::basic_string_view<CharT> fmt : fmt_invalid_nested_types<CharT>("s"))
    check_exception("The format-spec should consume the input or end with a '}'", fmt, input);

  // ***** Both have a format-spec
  check(SV("^^{###(1, 'a'), ##(42, '*')}^^^"), SV("{:^^31:#>11}"), input);
  check(SV("^^{###(1, 'a'), ##(42, '*')}^^^"), SV("{:^^31:#>11}"), input);
  check(SV("^^{###(1, 'a'), ##(42, '*')}^^^"), SV("{:^^{}:#>11}"), input, 31);
  check(SV("^^{###(1, 'a'), ##(42, '*')}^^^"), SV("{:^^{}:#>{}}"), input, 31, 11);

  check_exception("Argument index out of bounds", SV("{:^^{}:#>5}"), input);
  check_exception("Argument index out of bounds", SV("{:^^{}:#>{}}"), input, 31);

  check(SV("1: 'a', 42: '*'"), SV("{:n:m}"), input);
  check(SV("1, 'a', 42, '*'"), SV("{:n:n}"), input);
  check(SV("{1: 'a', 42: '*'}"), SV("{:m:m}"), input);
  check(SV("{1, 'a', 42, '*'}"), SV("{:m:n}"), input);
}

template <class CharT, class TestFunction, class ExceptionTest>
void test_pair_tuple(TestFunction check, ExceptionTest check_exception) {
  test_pair_tuple<CharT>(
      check, check_exception, std::set{std::make_pair(1, CharT('a')), std::make_pair(42, CharT('*'))});
  test_pair_tuple<CharT>(
      check, check_exception, std::set{std::make_tuple(1, CharT('a')), std::make_tuple(42, CharT('*'))});
}

//
// Tuple 1
//

template <class CharT, class TestFunction, class ExceptionTest>
void test_tuple_int(TestFunction check, ExceptionTest check_exception) {
  std::set input{std::make_tuple(42), std::make_tuple(99)};

  check(SV("{(42), (99)}"), SV("{}"), input);

  // ***** underlying has no format-spec

  // *** align-fill & width ***
  check(SV("{(42), (99)}     "), SV("{:17}"), input);
  check(SV("{(42), (99)}*****"), SV("{:*<17}"), input);
  check(SV("__{(42), (99)}___"), SV("{:_^17}"), input);
  check(SV("#####{(42), (99)}"), SV("{:#>17}"), input);

  check(SV("{(42), (99)}     "), SV("{:{}}"), input, 17);
  check(SV("{(42), (99)}*****"), SV("{:*<{}}"), input, 17);
  check(SV("__{(42), (99)}___"), SV("{:_^{}}"), input, 17);
  check(SV("#####{(42), (99)}"), SV("{:#>{}}"), input, 17);

  check_exception("The format-spec range-fill field contains an invalid character", SV("{:}<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{:{<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::<}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:-}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:+}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{: }"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:#}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{:0}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:.}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:L}"), input);

  // *** n
  check(SV("__(42), (99)___"), SV("{:_^15n}"), input);

  // *** type ***
  check(SV("__{(42), (99)}___"), SV("{:_^17m}"), input);
  check_exception("The range-format-spec type s requires formatting a character type", SV("{:s}"), input);
  check_exception("The range-format-spec type ?s requires formatting a character type", SV("{:?s}"), input);

  for (std::basic_string_view<CharT> fmt : fmt_invalid_types<CharT>("s"))
    check_exception("The format-spec should consume the input or end with a '}'", fmt, input);

  // ***** Only underlying has a format-spec
  check(SV("{(42)   , (99)   }"), SV("{::7}"), input);
  check(SV("{(42)***, (99)***}"), SV("{::*<7}"), input);
  check(SV("{_(42)__, _(99)__}"), SV("{::_^7}"), input);
  check(SV("{###(42), ###(99)}"), SV("{::#>7}"), input);

  check(SV("{(42)   , (99)   }"), SV("{::{}}"), input, 7);
  check(SV("{(42)***, (99)***}"), SV("{::*<{}}"), input, 7);
  check(SV("{_(42)__, _(99)__}"), SV("{::_^{}}"), input, 7);
  check(SV("{###(42), ###(99)}"), SV("{::#>{}}"), input, 7);

  check_exception("The format-spec range-fill field contains an invalid character", SV("{:::<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::}<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::{<}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::-}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::+}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:: }"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::#}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{::05}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::.}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::L}"), input);

  // *** type ***
  check(SV("{42, 99}"), SV("{::n}"), input);
  check_exception("The format specifier m requires a pair or a two-element tuple", SV("{::m}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::s}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::?s}"), input);

  for (std::basic_string_view<CharT> fmt : fmt_invalid_nested_types<CharT>("s"))
    check_exception("The format-spec should consume the input or end with a '}'", fmt, input);

  // ***** Both have a format-spec
  check(SV("^^{###(42), ###(99)}^^^"), SV("{:^^23:#>7}"), input);
  check(SV("^^{###(42), ###(99)}^^^"), SV("{:^^23:#>7}"), input);
  check(SV("^^{###(42), ###(99)}^^^"), SV("{:^^{}:#>7}"), input, 23);
  check(SV("^^{###(42), ###(99)}^^^"), SV("{:^^{}:#>{}}"), input, 23, 7);

  check_exception("Argument index out of bounds", SV("{:^^{}:#>5}"), input);
  check_exception("Argument index out of bounds", SV("{:^^{}:#>{}}"), input, 23);
}

//
// Tuple 3
//

template <class CharT, class TestFunction, class ExceptionTest>
void test_tuple_int_int_int(TestFunction check, ExceptionTest check_exception) {
  std::set input{std::make_tuple(42, 99, 0), std::make_tuple(1, 10, 100)}; // unordered

  check(SV("{(1, 10, 100), (42, 99, 0)}"), SV("{}"), input);

  // ***** underlying has no format-spec

  // *** align-fill & width ***
  check(SV("{(1, 10, 100), (42, 99, 0)}     "), SV("{:32}"), input);
  check(SV("{(1, 10, 100), (42, 99, 0)}*****"), SV("{:*<32}"), input);
  check(SV("__{(1, 10, 100), (42, 99, 0)}___"), SV("{:_^32}"), input);
  check(SV("#####{(1, 10, 100), (42, 99, 0)}"), SV("{:#>32}"), input);

  check(SV("{(1, 10, 100), (42, 99, 0)}     "), SV("{:{}}"), input, 32);
  check(SV("{(1, 10, 100), (42, 99, 0)}*****"), SV("{:*<{}}"), input, 32);
  check(SV("__{(1, 10, 100), (42, 99, 0)}___"), SV("{:_^{}}"), input, 32);
  check(SV("#####{(1, 10, 100), (42, 99, 0)}"), SV("{:#>{}}"), input, 32);

  check_exception("The format-spec range-fill field contains an invalid character", SV("{:}<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{:{<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::<}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:-}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:+}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{: }"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:#}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{:0}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:.}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:L}"), input);

  // *** n
  check(SV("__(1, 10, 100), (42, 99, 0)___"), SV("{:_^30n}"), input);

  // *** type ***
  check(SV("__{(1, 10, 100), (42, 99, 0)}___"), SV("{:_^32m}"), input);
  check_exception("The range-format-spec type s requires formatting a character type", SV("{:s}"), input);
  check_exception("The range-format-spec type ?s requires formatting a character type", SV("{:?s}"), input);

  for (std::basic_string_view<CharT> fmt : fmt_invalid_types<CharT>("s"))
    check_exception("The format-spec should consume the input or end with a '}'", fmt, input);

  // ***** Only underlying has a format-spec
  check(SV("{(1, 10, 100)  , (42, 99, 0)   }"), SV("{::14}"), input);
  check(SV("{(1, 10, 100)**, (42, 99, 0)***}"), SV("{::*<14}"), input);
  check(SV("{_(1, 10, 100)_, _(42, 99, 0)__}"), SV("{::_^14}"), input);
  check(SV("{##(1, 10, 100), ###(42, 99, 0)}"), SV("{::#>14}"), input);

  check(SV("{(1, 10, 100)  , (42, 99, 0)   }"), SV("{::{}}"), input, 14);
  check(SV("{(1, 10, 100)**, (42, 99, 0)***}"), SV("{::*<{}}"), input, 14);
  check(SV("{_(1, 10, 100)_, _(42, 99, 0)__}"), SV("{::_^{}}"), input, 14);
  check(SV("{##(1, 10, 100), ###(42, 99, 0)}"), SV("{::#>{}}"), input, 14);

  check_exception("The format-spec range-fill field contains an invalid character", SV("{:::<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::}<}"), input);
  check_exception("The format-spec range-fill field contains an invalid character", SV("{::{<}"), input);

  // *** sign ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::-}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::+}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{:: }"), input);

  // *** alternate form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::#}"), input);

  // *** zero-padding ***
  check_exception("A format-spec width field shouldn't have a leading zero", SV("{::05}"), input);

  // *** precision ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::.}"), input);

  // *** locale-specific form ***
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::L}"), input);

  // *** type ***
  check(SV("{1, 10, 100, 42, 99, 0}"), SV("{::n}"), input);
  check_exception("The format specifier m requires a pair or a two-element tuple", SV("{::m}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::s}"), input);
  check_exception("The format-spec should consume the input or end with a '}'", SV("{::?s}"), input);

  for (std::basic_string_view<CharT> fmt : fmt_invalid_nested_types<CharT>("s"))
    check_exception("The format-spec should consume the input or end with a '}'", fmt, input);

  // ***** Both have a format-spec
  check(SV("^^{##(1, 10, 100), ###(42, 99, 0)}^^^"), SV("{:^^37:#>14}"), input);
  check(SV("^^{##(1, 10, 100), ###(42, 99, 0)}^^^"), SV("{:^^37:#>14}"), input);
  check(SV("^^{##(1, 10, 100), ###(42, 99, 0)}^^^"), SV("{:^^{}:#>14}"), input, 37);
  check(SV("^^{##(1, 10, 100), ###(42, 99, 0)}^^^"), SV("{:^^{}:#>{}}"), input, 37, 14);

  check_exception("Argument index out of bounds", SV("{:^^{}:#>5}"), input);
  check_exception("Argument index out of bounds", SV("{:^^{}:#>{}}"), input, 37);
}

//
// Adaptor
//

class adaptor {
  using adaptee = std::set<int>;

public:
  using key_type = typename adaptee::key_type;
  using iterator = typename adaptee::iterator;

  iterator begin() { return data_.begin(); }
  iterator end() { return data_.end(); }

  explicit adaptor(std::set<int>&& data) : data_(std::move(data)) {}

private:
  adaptee data_;
};

static_assert(std::format_kind<adaptor> == std::range_format::set);

template <class CharT, class TestFunction, class ExceptionTest>
void test_adaptor(TestFunction check, ExceptionTest check_exception) {
  test_int<CharT>(check, check_exception, adaptor{std::set{1, 42, 2, -42}});
}

//
// Driver
//

template <class CharT, class TestFunction, class ExceptionTest>
void format_tests(TestFunction check, ExceptionTest check_exception) {
  test_char<CharT>(check, check_exception);

#ifndef _LIBCPP_HAS_NO_WIDE_CHARACTERS
  if (std::same_as<CharT, wchar_t>) // avoid testing twice
    test_char_to_wchar(check, check_exception);
#endif
  test_bool<CharT>(check, check_exception);
  test_bool_multiset<CharT>(check, check_exception);
  test_int<CharT>(check, check_exception);
  test_floating_point<CharT>(check, check_exception);
  test_pointer<CharT>(check, check_exception);
  test_string<CharT>(check, check_exception);

  test_status<CharT>(check, check_exception); // Has its own handler with its own parser

  test_pair_tuple<CharT>(check, check_exception);
  test_tuple_int<CharT>(check, check_exception);
  test_tuple_int_int_int<CharT>(check, check_exception);

  test_adaptor<CharT>(check, check_exception);
}

#endif // TEST_STD_UTILITIES_FORMAT_FORMAT_RANGE_FORMAT_RANGE_FMTSET_FORMAT_FUNCTIONS_TESTS_H
