diff --git a/libcxx/test/std/utilities/format/format.functions/escaped_output.ascii.pass.cpp b/libcxx/test/std/utilities/format/format.functions/escaped_output.ascii.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/escaped_output.ascii.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/escaped_output.ascii.pass.cpp
@@ -24,6 +24,7 @@
 #include "test_macros.h"
 #include "make_string.h"
 #include "test_format_string.h"
+#include "test_validation.h"
 
 #ifndef TEST_HAS_NO_LOCALIZATION
 #  include <iostream>
@@ -35,19 +36,14 @@
                        std::basic_string_view<CharT> expected, test_format_string<CharT, Args...> fmt, Args&&... args) {
   {
     std::basic_string<CharT> out = std::format(fmt, std::forward<Args>(args)...);
-#ifndef TEST_HAS_NO_LOCALIZATION
-    if (out != expected) {
-      if constexpr (std::same_as<CharT, char>)
-        std::cerr << "\nFormat string   " << fmt.get() << "\nExpected output " << expected << "\nActual output   "
-                  << out << '\n';
-#  ifndef TEST_HAS_NO_WIDE_CHARACTERS
-      else
-        std::wcerr << L"\nFormat string   " << fmt.get() << L"\nExpected output " << expected << L"\nActual output   "
-                   << out << L'\n';
-#  endif // TEST_HAS_NO_WIDE_CHARACTERS
-    }
-#endif // TEST_HAS_NO_LOCALIZATION
-    assert(out == expected);
+    REQUIRE(out == expected,
+            "\nFormat string   ",
+            fmt.get(),
+            "\nExpected output ",
+            expected,
+            "\nActual output   ",
+            out,
+            '\n');
   }
 #ifndef TEST_HAS_NO_LOCALIZATION
   {
diff --git a/libcxx/test/std/utilities/format/format.functions/escaped_output.unicode.pass.cpp b/libcxx/test/std/utilities/format/format.functions/escaped_output.unicode.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/escaped_output.unicode.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/escaped_output.unicode.pass.cpp
@@ -30,6 +30,7 @@
 #include "test_macros.h"
 #include "make_string.h"
 #include "test_format_string.h"
+#include "test_validation.h"
 
 #ifndef TEST_HAS_NO_LOCALIZATION
 #  include <iostream>
@@ -41,19 +42,14 @@
                        std::basic_string_view<CharT> expected, test_format_string<CharT, Args...> fmt, Args&&... args) {
   {
     std::basic_string<CharT> out = std::format(fmt, std::forward<Args>(args)...);
-#ifndef TEST_HAS_NO_LOCALIZATION
-    if (out != expected) {
-      if constexpr (std::same_as<CharT, char>)
-        std::cerr << "\nFormat string   " << fmt.get() << "\nExpected output " << expected << "\nActual output   "
-                  << out << '\n';
-#  ifndef TEST_HAS_NO_WIDE_CHARACTERS
-      else
-        std::wcerr << L"\nFormat string   " << fmt.get() << L"\nExpected output " << expected << L"\nActual output   "
-                   << out << L'\n';
-#  endif // TEST_HAS_NO_WIDE_CHARACTERS
-    }
-#endif // TEST_HAS_NO_LOCALIZATION
-    assert(out == expected);
+    REQUIRE(out == expected,
+            "\nFormat string   ",
+            fmt.get(),
+            "\nExpected output ",
+            expected,
+            "\nActual output   ",
+            out,
+            '\n');
   }
 #ifndef TEST_HAS_NO_LOCALIZATION
   {
diff --git a/libcxx/test/std/utilities/format/format.functions/format.locale.pass.cpp b/libcxx/test/std/utilities/format/format.functions/format.locale.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/format.locale.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/format.locale.pass.cpp
@@ -27,16 +27,20 @@
 #include "format_tests.h"
 #include "string_literal.h"
 #include "test_format_string.h"
+#include "test_validation.h"
 
 auto test =
     []<class CharT, class... Args>(
         std::basic_string_view<CharT> expected, test_format_string<CharT, Args...> fmt, Args&&... args) constexpr {
       std::basic_string<CharT> out = std::format(std::locale(), fmt, std::forward<Args>(args)...);
-      if constexpr (std::same_as<CharT, char>)
-        if (out != expected)
-          std::cerr << "\nFormat string   " << fmt.get() << "\nExpected output " << expected << "\nActual output   "
-                    << out << '\n';
-      assert(out == expected);
+      REQUIRE(out == expected,
+              "\nFormat string   ",
+              fmt.get(),
+              "\nExpected output ",
+              expected,
+              "\nActual output   ",
+              out,
+              '\n');
     };
 
 auto test_exception = []<class CharT, class... Args>(std::string_view, std::basic_string_view<CharT>, Args&&...) {
diff --git a/libcxx/test/std/utilities/format/format.functions/format.pass.cpp b/libcxx/test/std/utilities/format/format.functions/format.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/format.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/format.pass.cpp
@@ -29,23 +29,20 @@
 #include "format_tests.h"
 #include "string_literal.h"
 #include "test_format_string.h"
-
-#ifndef TEST_HAS_NO_LOCALIZATION
-#  include <iostream>
-#  include <type_traits>
-#endif
+#include "test_validation.h"
 
 auto test =
     []<class CharT, class... Args>(
         std::basic_string_view<CharT> expected, test_format_string<CharT, Args...> fmt, Args&&... args) constexpr {
       std::basic_string<CharT> out = std::format(fmt, std::forward<Args>(args)...);
-#ifndef TEST_HAS_NO_LOCALIZATION
-      if constexpr (std::same_as<CharT, char>)
-        if (out != expected)
-          std::cerr << "\nFormat string   " << fmt.get() << "\nExpected output " << expected << "\nActual output   "
-                    << out << '\n';
-#endif
-      assert(out == expected);
+      REQUIRE(out == expected,
+              "\nFormat string   ",
+              fmt.get(),
+              "\nExpected output ",
+              expected,
+              "\nActual output   ",
+              out,
+              '\n');
     };
 
 auto test_exception = []<class CharT, class... Args>(std::string_view, std::basic_string_view<CharT>, Args&&...) {
diff --git a/libcxx/test/std/utilities/format/format.functions/locale-specific_form.pass.cpp b/libcxx/test/std/utilities/format/format.functions/locale-specific_form.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/locale-specific_form.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/locale-specific_form.pass.cpp
@@ -93,6 +93,7 @@
 #include "format_tests.h"
 #include "string_literal.h"
 #include "test_format_string.h"
+#include "test_validation.h"
 
 #define STR(S) MAKE_STRING(CharT, S)
 #define SV(S) MAKE_STRING_VIEW(CharT, S)
@@ -127,11 +128,14 @@
   // *** format ***
   {
     std::basic_string<CharT> out = std::format(fmt, std::forward<Args>(args)...);
-    if constexpr (std::same_as<CharT, char>)
-      if (out != expected)
-        std::cerr << "\nFormat string   " << fmt.get() << "\nExpected output " << expected << "\nActual output   "
-                  << out << '\n';
-    assert(out == expected);
+    REQUIRE(out == expected,
+            "\nFormat string   ",
+            fmt.get(),
+            "\nExpected output ",
+            expected,
+            "\nActual output   ",
+            out,
+            '\n');
   }
   // *** vformat ***
   {
diff --git a/libcxx/test/std/utilities/format/format.functions/vformat.locale.pass.cpp b/libcxx/test/std/utilities/format/format.functions/vformat.locale.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/vformat.locale.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/vformat.locale.pass.cpp
@@ -23,11 +23,12 @@
 #include "test_macros.h"
 #include "format_tests.h"
 #include "string_literal.h"
+#include "test_validation.h"
 
 auto test = []<class CharT, class... Args>(
                 std::basic_string_view<CharT> expected, std::basic_string_view<CharT> fmt, Args&&... args) constexpr {
   std::basic_string<CharT> out = std::vformat(std::locale(), fmt, std::make_format_args<context_t<CharT>>(args...));
-  assert(out == expected);
+  REQUIRE(out == expected, "\nFormat string   ", fmt, "\nExpected output ", expected, "\nActual output   ", out, '\n');
 };
 
 auto test_exception =
@@ -37,10 +38,18 @@
         [[maybe_unused]] Args&&... args) {
 #ifndef TEST_HAS_NO_EXCEPTIONS
       try {
-        (void)std::vformat(std::locale(), fmt, std::make_format_args<context_t<CharT>>(args...));
-        assert(false);
+        TEST_IGNORE_NODISCARD std::vformat(std::locale(), fmt, std::make_format_args<context_t<CharT>>(args...));
+        FAIL("\nFormat string   ", fmt, "\nDidn't throw an exception.\n");
       } catch ([[maybe_unused]] const std::format_error& e) {
-        LIBCPP_ASSERT(e.what() == what);
+        LIBCPP_REQUIRE(
+            e.what() == what,
+            "\nFormat string   ",
+            fmt,
+            "\nExpected exception ",
+            what,
+            "\nActual exception   ",
+            e.what(),
+            '\n');
         return;
       }
       assert(false);
diff --git a/libcxx/test/std/utilities/format/format.functions/vformat.pass.cpp b/libcxx/test/std/utilities/format/format.functions/vformat.pass.cpp
--- a/libcxx/test/std/utilities/format/format.functions/vformat.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.functions/vformat.pass.cpp
@@ -22,11 +22,12 @@
 #include "test_macros.h"
 #include "format_tests.h"
 #include "string_literal.h"
+#include "test_validation.h"
 
 auto test = []<class CharT, class... Args>(
                 std::basic_string_view<CharT> expected, std::basic_string_view<CharT> fmt, Args&&... args) constexpr {
   std::basic_string<CharT> out = std::vformat(fmt, std::make_format_args<context_t<CharT>>(args...));
-  assert(out == expected);
+  REQUIRE(out == expected, "\nFormat string   ", fmt, "\nExpected output ", expected, "\nActual output   ", out, '\n');
 };
 
 auto test_exception =
@@ -37,9 +38,18 @@
 #ifndef TEST_HAS_NO_EXCEPTIONS
       try {
         TEST_IGNORE_NODISCARD std::vformat(fmt, std::make_format_args<context_t<CharT>>(args...));
-        assert(false);
+        FAIL("\nFormat string   ", fmt, "\nDidn't throw an exception.\n");
       } catch ([[maybe_unused]] const std::format_error& e) {
-        LIBCPP_ASSERT(e.what() == what);
+        LIBCPP_REQUIRE(
+            e.what() == what,
+            "\nFormat string   ",
+            fmt,
+            "\nExpected exception ",
+            what,
+            "\nActual exception   ",
+            e.what(),
+            '\n');
+
         return;
       }
       assert(false);
diff --git a/libcxx/test/std/utilities/format/format.tuple/format.functions.format.pass.cpp b/libcxx/test/std/utilities/format/format.tuple/format.functions.format.pass.cpp
--- a/libcxx/test/std/utilities/format/format.tuple/format.functions.format.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.tuple/format.functions.format.pass.cpp
@@ -30,22 +30,12 @@
 #include "format.functions.tests.h"
 #include "test_format_string.h"
 #include "test_macros.h"
-
-#ifndef TEST_HAS_NO_LOCALIZATION
-#  include <iostream>
-#  include <concepts>
-#endif
+#include "test_validation.h"
 
 auto test = []<class CharT, class... Args>(
                 std::basic_string_view<CharT> expected, test_format_string<CharT, Args...> fmt, Args&&... args) {
   std::basic_string<CharT> out = std::format(fmt, std::forward<Args>(args)...);
-#ifndef TEST_HAS_NO_LOCALIZATION
-  if constexpr (std::same_as<CharT, char>)
-    if (out != expected)
-      std::cerr << "\nFormat string   " << fmt.get() << "\nExpected output " << expected << "\nActual output   " << out
-                << '\n';
-#endif // TEST_HAS_NO_LOCALIZATION
-  assert(out == expected);
+  REQUIRE(out == expected, "\nFormat string   ", fmt, "\nExpected output ", expected, "\nActual output   ", out, '\n');
 };
 
 auto test_exception = []<class CharT, class... Args>(std::string_view, std::basic_string_view<CharT>, Args&&...) {
diff --git a/libcxx/test/std/utilities/format/format.tuple/format.functions.vformat.pass.cpp b/libcxx/test/std/utilities/format/format.tuple/format.functions.vformat.pass.cpp
--- a/libcxx/test/std/utilities/format/format.tuple/format.functions.vformat.pass.cpp
+++ b/libcxx/test/std/utilities/format/format.tuple/format.functions.vformat.pass.cpp
@@ -27,22 +27,12 @@
 
 #include "test_macros.h"
 #include "format.functions.tests.h"
-
-#ifndef TEST_HAS_NO_LOCALIZATION
-#  include <iostream>
-#  include <concepts>
-#endif
+#include "test_validation.h"
 
 auto test = []<class CharT, class... Args>(
                 std::basic_string_view<CharT> expected, std::basic_string_view<CharT> fmt, Args&&... args) {
   std::basic_string<CharT> out = std::vformat(fmt, std::make_format_args<context_t<CharT>>(args...));
-#ifndef TEST_HAS_NO_LOCALIZATION
-  if constexpr (std::same_as<CharT, char>)
-    if (out != expected)
-      std::cerr << "\nFormat string   " << fmt << "\nExpected output " << expected << "\nActual output   " << out
-                << '\n';
-#endif // TEST_HAS_NO_LOCALIZATION
-  assert(out == expected);
+  REQUIRE(out == expected, "\nFormat string   ", fmt, "\nExpected output ", expected, "\nActual output   ", out, '\n');
 };
 
 auto test_exception =
@@ -53,22 +43,18 @@
 #ifndef TEST_HAS_NO_EXCEPTIONS
       try {
         TEST_IGNORE_NODISCARD std::vformat(fmt, std::make_format_args<context_t<CharT>>(args...));
-#  if !defined(TEST_HAS_NO_LOCALIZATION)
-        if constexpr (std::same_as<CharT, char>)
-          std::cerr << "\nFormat string   " << fmt << "\nDidn't throw an exception.\n";
-#  endif //  !defined(TEST_HAS_NO_LOCALIZATION
-        assert(false);
+        FAIL("\nFormat string   ", fmt, "\nDidn't throw an exception.\n");
       } catch ([[maybe_unused]] const std::format_error& e) {
-#  if defined(_LIBCPP_VERSION)
-#    if !defined(TEST_HAS_NO_LOCALIZATION)
-        if constexpr (std::same_as<CharT, char>) {
-          if (e.what() != what)
-            std::cerr << "\nFormat string   " << fmt << "\nExpected exception " << what << "\nActual exception   "
-                      << e.what() << '\n';
-        }
-#    endif // !defined(TEST_HAS_NO_LOCALIZATION
-        assert(e.what() == what);
-#  endif   // defined(_LIBCPP_VERSION)
+        LIBCPP_REQUIRE(
+            e.what() == what,
+            "\nFormat string   ",
+            fmt,
+            "\nExpected exception ",
+            what,
+            "\nActual exception   ",
+            e.what(),
+            '\n');
+
         return;
       }
       assert(false);
diff --git a/libcxx/test/support/test_validation.h b/libcxx/test/support/test_validation.h
new file mode 100644
--- /dev/null
+++ b/libcxx/test/support/test_validation.h
@@ -0,0 +1,103 @@
+//===----------------------------------------------------------------------===//
+//
+// 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_SUPPORT_TEST_VALIDATION_H
+#define TEST_SUPPORT_TEST_VALIDATION_H
+
+// Contains a set of validation macros.
+//
+// Note these test were added after C++20 was well supported by the compilers
+// used. To make the implementation simple the macros require C++20 or newer.
+// It's not expected that existing tests start to use these new macros.
+//
+// These macros are an alternative to using assert. The differences are:
+// - The assert message isn't localized.
+// - It's possible to log additional information. This is useful when the
+//   function asserting is a helper function. In these cases the assertion
+//   failure contains to little information to find the issue. For example, in
+//   the format functions, the really useful information is the actual output,
+//   the expected output, and the format string used. These macros allow
+//   logging additional arguments.
+
+#include "test_macros.h"
+
+#include <cstdio>
+#include <cstdlib>
+
+#ifndef TEST_HAS_NO_LOCALIZATION
+#  include <iostream>
+#endif // TEST_HAS_NO_LOCALIZATION
+
+#if TEST_STD_VER > 17
+
+#  ifndef TEST_HAS_NO_LOCALIZATION
+template <class T>
+concept test_char_streamable = requires(T&& value) { std::cerr << std::forward<T>(value); };
+#  endif // TEST_HAS_NO_LOCALIZATION
+
+// Logs the error and calls exit.
+//
+// It show a generic assert like message and if possible streams the args to
+// std::cerr else streams a default message.  Not being able to stream is not
+// considered and error. For example, streaming to std::wcerr doesn't work
+// properly in the CI. Therefore the formatting tests should only stream to
+// std::cerr.
+template <class... Args>
+[[noreturn]] void test_log_error(const char* condition, const char* file, int line, [[maybe_unused]] Args&&... args) {
+  const char* msg = condition ? "Assertion failure: " : "Unconditional failure:";
+  fprintf(stderr, "%s%s %s %d\n", msg, condition, file, line);
+#  ifndef TEST_HAS_NO_LOCALIZATION
+  if constexpr ((test_char_streamable<Args> && ...))
+    ((std::cerr << std::forward<Args>(args)), ...);
+  else
+    std::cerr << "Message discarded since it can't be streamed to std::cerr.\n";
+#  endif
+  exit(EXIT_FAILURE);
+}
+
+inline constexpr auto test_fail = []<class... Args>(const char* file, int line, Args&&... args) {
+  test_log_error("", file, line, std::forward<Args>(args)...);
+};
+
+inline constexpr auto test_require =
+    []<class... Args>(bool condition, const char* condition_str, const char* file, int line, Args&&... args) {
+      if (condition)
+        return;
+
+      test_log_error(condition_str, file, line, std::forward<Args>(args)...);
+    };
+
+inline constexpr auto test_libcpp_require =
+    []<class... Args>(
+        [[maybe_unused]] bool condition,
+        [[maybe_unused]] const char* condition_str,
+        [[maybe_unused]] const char* file,
+        [[maybe_unused]] int line,
+        [[maybe_unused]] Args&&... args) {
+#  if defined(_LIBCPP_VERSION)
+      test_require(condition, condition_str, file, line, std::forward<Args>(args)...);
+#  endif // _LIBCPP_VERSION
+    };
+
+// assert(false) replacement
+#  define FAIL(...) test_fail(__FILE__, __LINE__ __VA_OPT__(, ) __VA_ARGS__)
+
+// assert replacement.
+#  define REQUIRE(CONDITION, ...) test_require(CONDITION, #CONDITION, __FILE__, __LINE__ __VA_OPT__(, ) __VA_ARGS__)
+
+// LIBCPP_ASSERT replacement
+//
+// This requirement is only tested when the test suite is used for libc++.
+// This allows checking libc++ specific requirements, for example the error
+// messages of exceptions.
+#  define LIBCPP_REQUIRE(CONDITION, ...)                                                                               \
+    test_libcpp_require(CONDITION, #CONDITION, __FILE__, __LINE__ __VA_OPT__(, ) __VA_ARGS__)
+
+#endif // TEST_STD_VER > 17
+
+#endif // TEST_SUPPORT_TEST_VALIDATION_H