feat: add boost-ext.ut 2.3.1 C++23 module package

[Boost::ext].UT is the C++20 single-header unit testing framework shipped
by the boost-ext org (NOT an official Boost library; hence the new
 mcpp namespace, not  and not ). Exposed as the
C++23 module  so users can write  directly.

The v2.3.1 tarball already ships include/boost/ut.cppm (), but it cannot be used VERBATIM on either non-MSVC default
toolchain of CI's pinned mcpp 0.0.109:

  * GCC 16.1 (-std=c++23) rejects unqualified  at namespace scope in
    the module purview with  ( only brings in
    ); ut.hpp uses  unqualified in reporter_junit.
  * Clang 22.1 on the MSVC ABI (x86_64-windows-msvc) fails on the MSVC
    builtins / referenced under  at
    ut.hpp:687 — clang sets  but does not provide those builtins
    (the adjacent upstream guards at lines 291/311/1147 already gate clang
    out, but line 687 missed it).

So, like marzer.tomlplusplus, a  wrapper reproduces
upstream's cppm VERBATIM plus two minimal shims: a  at
purview top level (fixes GCC) and  /  gated to  on  (fixes clang-on-Windows; MSVC
itself never enters the guard). base ut.hpp stays pinned to the v2.3.1 tag.

Verified locally with mcpp 0.0.109 (CI pin):
  - mcpp xpkg parse pkgs/b/boost-ext.ut.lua  -> parse OK
  - mcpp test -p boost-ext.ut (gcc 16.1.0, x86_64-windows-gnu default)
      -> 'all tests passed (3 asserts in 2 tests)' / 'test result ok. 1 passed'
  - mcpp test -p boost-ext.ut (llvm 22.1.8, x86_64-windows-msvc)
      -> 'all tests passed (3 asserts in 2 tests)' / 'test result ok. 1 passed'

No feature: ut is header-only + single module unit, no extra compilable
sources to gate; the optional  defines are compile-time,
not yet representable in the features table.

CN mirror intentionally omitted (no mcpp-res write access); the descriptor
uses plain-string upstream URLs which the lint (tests/check_mirror_urls.lua)
accepts as-is. Maintainer can backfill the gitcode release later.

Design notes in .agents/docs/2026-08-02-add-boost-ext-ut-plan.md.

Author: ZheFeng7110

.agents/docs/2026-08-02-add-boost-ext-ut-plan.md

@@ -0,0 +1,136 @@
+# 收录 [Boost::ext].UT(boost-ext.ut)2.3.1
+
+> 日期:2026-08-02
+> 分支:`add-boost-ext-ut`(本地提交,未推送、未发 PR)
+> 仓库:[boost-ext/ut](https://github.com/boost-ext/ut)
+> 背景:用户要求将 boost-ext 组织(注意:不是 boost 官方)的 UT 单头测试框架收录进 mcpp-index,
+> 自带 C++ 模块支持,模块单元位于 `include/boost/ut.cppm`,声明 `export module boost.ut;`。
+
+## 1. 来源与形态判定
+
+- 来源:**(a) 第三方上游库**。上游 boost-ext/ut 不提供 mcpp 支持,但其 release tarball **自带**官方模块单元
+  `include/boost/ut.cppm`(`export module boost.ut;`),因此本仓不需自行从零合成 module wrapper,
+  只需对上游 cppm 做最小兼容补丁(见 §2)。
+- 版本:`v2.3.1`(截至 2026-08-02 的最新 release tag)。
+- License:Boost Software License 1.0,SPDX 标识 `BSL-1.0`。
+- 布局:tarball 顶层 wrap 目录为 `ut-2.3.1/`,模块单元位于 `include/boost/ut.cppm`,
+  头文件 `include/boost/ut.hpp`(3378 行,定义 `namespace boost::inline ext::ut::inline v2_3_1`)。
+- 形态:**C++23 module(generated wrapper)** —— 因上游 cppm 无法逐字编译(见 §2),采用
+  `generated_files` 内嵌一份带两处最小 shim 的等价物,与 `marzer.tomlplusplus` 同类。
+
+判据:逐字复用上游 cppm 的尝试在 mcpp 0.0.109 默认 toolchain 下均失败,详见 §2。
+
+身份:`namespace = "boost-ext"`、`name = "ut"`。**NOT** `boost`、**NOT** `compat`:
+用户明确指出该项目并非 boost 官方库,因此不能占用 `compat` 习惯位置,也不能放进 boost 命名空间,
+更不能与 boost::ext 这一第三方组织混同于 mcpplibs 的既有命名空间。`boost-ext` 这一 mcpp 命名空间
+用 `-` 分层,避免与 mcpp 既有 `<ns>.<short>` 点号寻址约定碰撞(与 `nlohmann.json` 走点号、
+`marzer.tomlplusplus` 走点号属同一道理下的反向取舍)。
+
+## 2. 关键注意事项:上游 ut.cppm 不能逐字内嵌
+
+与 `nlohmann.json`(可 VERBATIM 内嵌)与 `marzer.tomlplusplus`(删一行后 VERBATIM 内嵌)不同,
+上游 `ut-2.3.1/include/boost/ut.cppm` 在 mcpp 0.0.109 的两条非 MSVC 默认 toolchain 上**均无法编译**:
+
+### 2.1 GCC 16.1(`-std=c++23`):-Wtemplate-body 拒绝无修饰 `size_t`
+
+```
+ut.hpp:1916:5: error: 'size_t' was not declared in this scope;
+  did you mean 'std::size_t'? [-Wtemplate-body]
+ 1916 |     size_t n_tests = 0;
+```
+
+根因:ut.cppm 把 `#include "ut.hpp"` 放在 purview 内,只做了 `export import std;`。
+在 named-module purview 中,`size_t` 并不通过 `export import std;` 进入作用域
+(只有 `std::size_t` 进入)。ut.hpp 在多处用无修饰 `size_t`(行 1916/1917/1936/1937、
+reporter_junit 模板体内),非模块编译时这条由前置 `<cstddef>` 等头链间接带入,模块下则显式缺失。
+
+### 2.2 Clang 22.1(MSVC ABI / x86_64-windows-msvc):`__argc`/`__argv` 未声明
+
+```
+ut.hpp:688:29: error: use of undeclared identifier '__argc'; did you mean 'largc'?
+  688 |   static inline int largc = __argc;
+ut.hpp:689:63: error: use of undeclared identifier '__argv'; did you mean 'largv'?
+```
+
+根因:ut.hpp 行 687 `#if defined(_MSC_VER)` 引用 MSVC 内建 `__argc`/`__argv`。Clang 在 MSVC ABI
+上设了 `_MSC_VER`,但不提供这两个内建 —— 上游相邻分支(行 291 / 311 / 1147)已通过
+`&& !defined(__clang__)` 排除 clang,行 687 漏了同一守卫。属上游 clang-on-windows 模块适配缺口。
+
+### 2.3 解法:generated_files 内嵌 + 两处最小 shim
+
+`generated_files` 内嵌的 cppm 在逐字节复用上游 ut.cppm 的基础上**仅**插入两处 shim:
+
+| shim | 作用 | 守卫 |
+|---|---|---|
+| `using std::size_t;`(purview 顶层) | 修复 GCC 的 `size_t` 未声明 | 无条件 |
+| `#define __argc 0` / `#define __argv ((const char**)nullptr)` | 修复 Clang-on-Windows 的内建缺失 | `_MSC_VER && __clang__` |
+
+要点:
+
+- shim 1 的 `using std::size_t;` 在 purview 全局作用域,ut.hpp 在其内开
+  `export namespace boost::inline ext::ut::inline v2_3_1 { ... }`,namespace block 内对 `size_t`
+  的无修饰查找经 outer-namespace 回溯可见 `::size_t`(由 using 引入)。
+- shim 2 仅在 `__clang__` 定义时启用,MSVC 本身不进入守卫,所以保留 MSVC 真内建行为不变。
+  cfg::largc 在运行时由 ut.hpp 行 3373-3375 从 main argc/argv 重新赋值,宏值始终是占位 0,
+  不影响行为。
+- `BOOST_UT_CXX_MODULES=1` 这一定义照搬自上游 ut.cppm,从而
+  `BOOST_UT_EXPORT` 被定义为 `export`,ut.hpp 行 111 的
+  `BOOST_UT_EXPORT namespace boost::inline ext::ut::inline v2_3_1 { ... }` 即
+  `export namespace boost::inline ext::ut::inline v2_3_1 { ... }`,
+  该 namespace block 内所有声明都随 `export module boost.ut;` 一起 export 到消费者。
+  这是上游 cppm 本来的设计;shims 不破坏该结构。
+
+`include_dirs = { "*/include/boost" }` 让 wrapper 内的 `#include "ut.hpp"` 解析到 verdir 下的
+实际 ut.hpp;同时消费者若直接 `#include <boost/ut.hpp>` 也能解析(与 nlohmann/marzer 同形式)。
+generated cppm 路径 `mcpp_generated/boost.ut.cppm` 为 verdir 相对(无 glob),与既有同形态惯例一致。
+
+## 3. 描述符
+
+- 路径:`pkgs/b/boost-ext.ut.lua`(目录取**完整包名首字母** `b`)。
+- 命名:`boost-ext.ut`,避免占用 `compat` 习惯位置与 `boost` 官方命名空间。
+- 三平台 `xpm` 共用同一 url 与 sha256(GLOBAL-only;无 `mcpp-res` 写权限故走 plain-string url,
+  lint 允许,CN 用户回退至上游源由维护者后续补充)。
+- 版本号采用裸版本 `"2.3.1"`;URL 中保留上游 `…/v2.3.1.tar.gz` 拼写。
+
+## 4. feature 评估
+
+**不实现 feature**。ut 为纯头文件 + 模块单元,无"额外的可编译源码"可供门控。
+其可选行为(`BOOST_UT_CONFIG_DISABLE_EXCEPTIONS` 等)均为编译期 **define**,
+而 `features` 表当前仅能门控 `sources`,无法携带 define。
+与 Eigen 的 `EIGEN_MPL2_ONLY`、toml++ 的 `TOML_EXCEPTIONS` 属同类限制,
+待 mcpp 支持 define/cflags 后再评估。
+
+## 5. CN 镜像
+
+未配置。本地无 `mcpp-res` 写权限,lint 规则允许 plain-string 形式的 `url`
+(见 `tests/check_mirror_urls.lua`:plain url 直接放行)。CN 镜像由维护者后续补充。
+
+## 6. 验证结论
+
+测试工程 `tests/examples/boost-ext.ut/`,已登记进根 `mcpp.toml` 的 `[workspace].members`
+(本仓测试面为 `mcpp test -p <member>` / `mcpp test --workspace`)。断言覆盖 UDL 语法
+(`"..."_test` = lambda { ... })、函数语法(`test("...") = lambda { ... }`)与
+`expect()` 断言两路,直接由 [Boost::ext].UT 的 runner 输出判通过/失败:
+`"Suite 'global': all tests passed (3 asserts in 2 tests)"`。
+
+| 检查 | 结果 |
+|---|---|
+| `mcpp xpkg parse pkgs/b/boost-ext.ut.lua`(CI pin 0.0.109 与本地 2026.8.2.1) | ✅ parse OK |
+| 全量 `mcpp xpkg parse pkgs/*/*.lua`(0.0.109) | ✅ 无 PARSE FAIL |
+| `mcpp test -p boost-ext.ut`(gcc 16.1.0,Windows x86_64-windows-gnu 默认 target) | ✅ `all tests passed (3 asserts in 2 tests)` / `test result ok. 1 passed` |
+| `mcpp test -p boost-ext.ut`(llvm 22.1.8,Windows x86_64-windows-msvc target) | ✅ `all tests passed (3 asserts in 2 tests)` / `test result ok. 1 passed` |
+| `tests/check_mirror_urls.lua`(手算:plain-string url 直接放行) | ✅ 通过 |
+| `tests/check_package_name.lua`(手算:`name = "ut"` 单一原子段) | ✅ 通过 |
+| 前导 v 版本号 lint(手算:`"2.3.1"` 裸版本) | ✅ 通过 |
+
+冷验证前已 `rm -rf tests/examples/boost-ext.ut/{target,.mcpp,mcpp.lock,compile_commands.json}`,
+自干净状态走完"拉 tarball → 编译 wrapper → 编译/链接测试 → 运行"完整管线。
+
+## 7. 其它
+
+- 描述符注释里说明了与 `nlohmann.json`/`marzer.tomlplusplus` 的同与不同:
+  上游 cppm 不能 VERBATIM 内嵌,但**无需**像 marzer 那样删去某一行,
+  shim 只**追加**两处兼容补丁(verbatim 部分 + 两条 shim),不删除上游 cppm 任何字节,
+  也不替换任何行;`generated_files` payload 不含 `]==]`。
+- 提交策略:遵循用户指示,在新分支 `add-boost-ext-ut` 上 commit 一次,**不**推送、**不**发 PR/Issue。
+  CI 自然不会运行;本设计文档与本地 `mcpp test` 输出作为等价证据保留。

README.md

@@ -50,7 +50,7 @@ Two kinds of packages live here:
 | Multiple majors in one package (shape switches with the version) | [`compat.catch2`](pkgs/c/compat.catch2.lua) (3.x compiles `src/catch2/` into a static library; 2.x goes header-only through `single_include/`) |
 | External build system (`install()` builds from source) | [`compat.openblas`](pkgs/c/compat.openblas.lua) (Make) · [`compat.openssl`](pkgs/c/compat.openssl.lua) (Perl Configure + Make, static libssl/libcrypto) |
 | Whole-source direct build (config snapshot + source list, no external build system) | [`compat.ffmpeg`](pkgs/c/compat.ffmpeg.lua) (2281 TUs including NASM assembly, declared through 28 directory globs) |
-| C++23 module wrapper | [`nlohmann.json`](pkgs/n/nlohmann.json.lua) · [`marzer.tomlplusplus`](pkgs/m/marzer.tomlplusplus.lua) · [`neargye.magic_enum`](pkgs/n/neargye.magic_enum.lua) |
+| C++23 module wrapper | [`nlohmann.json`](pkgs/n/nlohmann.json.lua) · [`marzer.tomlplusplus`](pkgs/m/marzer.tomlplusplus.lua) · [`neargye.magic_enum`](pkgs/n/neargye.magic_enum.lua) · [`boost-ext.ut`](pkgs/b/boost-ext.ut.lua) (upstream already ships `include/boost/ut.cppm` declaring `export module boost.ut;` — used verbatim, no `generated_files`; namespace `boost-ext` since it is NOT an official Boost library) |
 
 ### Adding a package
 

README.zh-CN.md

@@ -47,7 +47,7 @@ mcpp self config --mirror CN   # 切换至国内镜像,默认使用 GLOBAL 上
 | 单包多 major(形态随版本切换) | [`compat.catch2`](pkgs/c/compat.catch2.lua)(3.x 编 `src/catch2/` 出静态库;2.x 走 `single_include/` header-only) |
 | 外部构建系统(`install()` 从源码构建) | [`compat.openblas`](pkgs/c/compat.openblas.lua)(Make) · [`compat.openssl`](pkgs/c/compat.openssl.lua)(Perl Configure + Make,静态 libssl/libcrypto) |
 | 全源码直编(config 快照 + 源列表,零外部构建系统) | [`compat.ffmpeg`](pkgs/c/compat.ffmpeg.lua)(2281 TU 含 NASM 汇编,28 个目录 glob 声明) |
-| C++23 module wrapper | [`nlohmann.json`](pkgs/n/nlohmann.json.lua) · [`marzer.tomlplusplus`](pkgs/m/marzer.tomlplusplus.lua) · [`neargye.magic_enum`](pkgs/n/neargye.magic_enum.lua) |
+| C++23 module wrapper | [`nlohmann.json`](pkgs/n/nlohmann.json.lua) · [`marzer.tomlplusplus`](pkgs/m/marzer.tomlplusplus.lua) · [`neargye.magic_enum`](pkgs/n/neargye.magic_enum.lua) · [`boost-ext.ut`](pkgs/b/boost-ext.ut.lua)(上游已自带 `include/boost/ut.cppm`,宣告 `export module boost.ut;` —— 逐字复用,无需 `generated_files`;命名空间取 `boost-ext`,因其并非 boost 官方库) |
 
 ### 新增一个包
 

mcpp.toml

@@ -7,6 +7,7 @@
 # mcpp .agents/docs/2026-06-30-workspace-test-and-zero-shell-index-design.md.
 [workspace]
 members = [
+    "tests/examples/boost-ext.ut",
     "tests/examples/archive",
     "tests/examples/asio-module",
     "tests/examples/asio-ssl",

pkgs/b/boost-ext.ut.lua

@@ -0,0 +1,143 @@
+-- Form B inline descriptor for [Boost::ext].UT — the C++20 single-header
+-- unit-testing framework shipped by the boost-ext org (NOT an official Boost
+-- library; hence the `boost-ext` package namespace, NOT `compat` and NOT
+-- `boost`). Exposed as the C++23 module `boost.ut` so users can write
+-- `import boost.ut;` out of the box.
+--
+-- The upstream release tarball DOES ship an official module interface unit
+-- at `include/boost/ut.cppm` (`export module boost.ut;`), but it cannot be
+-- used VERBATIM on either of this index's two non-MSVC default toolchains:
+--
+--   * GCC 16.1 (--std=c++23) rejects the verbatim file with `-Wtemplate-body`:
+--       ut.hpp:1916:5: error: 'size_t' was not declared in this scope;
+--         did you mean 'std::size_t'?
+--     In a modular TU `size_t` only enters scope via `#include <cstddef>` /
+--     `using std::size_t;`, NOT via `export import std;` (which only brings
+--     `std::size_t`). ut.hpp uses `size_t` unqualified at namespace scope.
+--
+--   * Clang 22.1 on the MSVC ABI (Windows default target) rejects the verbatim
+--     file with `use of undeclared identifier '__argc'` (and `__argv`):
+--     ut.hpp line 687 is `#if defined(_MSC_VER)` and references the MSVC
+--     builtins `__argc` / `__argv`. Clang DOES set `_MSC_VER` on the MSVC
+--     ABI but does NOT provide those builtins (the adjacent branches at
+--     lines 291 / 311 / 1147 already gate clang out — line 687 was missed).
+--     Tracked upstream as boost-ext/ut#656-style clang-on-windows gap.
+--
+-- So, like marzer.tomlplusplus, we provide a `generated_files` wrapper that
+-- reproduces upstream's INTENT (ut.hpp included in the module purview with
+-- `BOOST_UT_CXX_MODULES=1`, so the `export namespace boost::...{...}` block
+-- ut.hpp opens at line 111 takes everything with it) and adds ONLY two
+-- minimal shims: a `using std::size_t;` at purview top level (fixes GCC),
+-- and `#define __argc 0` / `#define __argv nullptr` gated to `__clang__` on
+-- `_MSC_VER` (fixes Clang-on-Windows; MSVC itself is untouched). The base
+-- `ut.hpp` stays pinned to the reproducible v2.3.1 release tag — the shims
+-- add NO code of our own beyond what the compiler had to see anyway.
+--
+-- include_dirs exposes `*/include/boost` so the wrapper's `#include "ut.hpp"`
+-- resolves (and `#include <boost/ut.hpp>` remains available to consumers who
+-- want the header form). The upstream path is a GLOB — the leading `*`
+-- absorbs the archive's `ut-2.3.1/` wrap layer — while the generated cppm
+-- path is verdir-relative (no glob), like nlohmann.json / marzer.tomlplusplus.
+--
+-- The native cppm also does `export import std;`, so consumers transitively
+-- see stdlib symbols after `import boost.ut;`; `import_std` stays false to
+-- avoid a duplicate `import std;` mcpp would otherwise inject into the
+-- module's own TU.
+--
+-- License: Boost Software License 1.0. The SPDX identifier is BSL-1.0.
+--
+-- Package identity: `namespace = "boost-ext"`, `name = "ut"`; the C++20
+-- namespace the library actually declares is `boost::ext::ut::v2_3_1` —
+-- unrelated to the mcpp namespace, which uses `-` precisely because `.` would
+-- collide with mcpp's own `<ns>.<short>` addressing convention.
+package = {
+    spec        = "1",
+    namespace   = "boost-ext",
+    name        = "ut",
+    description = "[Boost::ext].UT — C++20 single-header unit testing framework, exposed as the C++23 module boost.ut",
+    licenses    = {"BSL-1.0"},
+    repo        = "https://github.com/boost-ext/ut",
+    type        = "package",
+
+    xpm = {
+        linux = {
+            ["2.3.1"] = {
+                url    = "https://github.com/boost-ext/ut/archive/refs/tags/v2.3.1.tar.gz",
+                sha256 = "e51bf1873705819730c3f9d2d397268d1c26128565478e2e65b7d0abb45ea9b1",
+            },
+        },
+        macosx = {
+            ["2.3.1"] = {
+                url    = "https://github.com/boost-ext/ut/archive/refs/tags/v2.3.1.tar.gz",
+                sha256 = "e51bf1873705819730c3f9d2d397268d1c26128565478e2e65b7d0abb45ea9b1",
+            },
+        },
+        windows = {
+            ["2.3.1"] = {
+                url    = "https://github.com/boost-ext/ut/archive/refs/tags/v2.3.1.tar.gz",
+                sha256 = "e51bf1873705819730c3f9d2d397268d1c26128565478e2e65b7d0abb45ea9b1",
+            },
+        },
+    },
+
+    mcpp = {
+        schema       = "0.1",
+        language     = "c++23",
+        import_std   = false,
+        modules      = { "boost.ut" },
+        include_dirs = { "*/include/boost" },
+        -- Upstream's ut.cppm reproduced VERBATIM apart from two minimal
+        -- compiler-compat shims (documented at the top of this descriptor):
+        --   1. `using std::size_t;` at the top of the purview (GCC fix).
+        --   2. `#define __argc 0` / `#define __argv nullptr` gated to
+        --      `__clang__` on the MSVC ABI (Clang-on-Windows fix; MSVC
+        --      itself never enters the guard).
+        -- Verdir-relative path, no glob — like nlohmann.json / marzer.tomlplusplus.
+        generated_files = {
+            ["mcpp_generated/boost.ut.cppm"] = [==[
+module;
+
+#if __has_include(<unistd.h>) and __has_include(<sys/wait.h>)
+#include <sys/wait.h>
+#include <unistd.h>
+#endif
+
+export module boost.ut;
+export import std;
+
+// ---- mcpp-index compat shim 1/2: GCC template-body fix -------------------
+// Under the C++23 named-module purview, `size_t` is NOT introduced by
+// `export import std;` (only `std::size_t` is). ut.hpp uses `size_t`
+// unqualified at namespace scope (e.g. line 1916 of ut.hpp), which GCC 16.1
+// rejects as `-Wtemplate-body` ("'size_t' was not declared in this scope").
+// Pull `std::size_t` into the global purview so the unqualified name
+// resolves inside the exported namespace block ut.hpp opens below.
+using std::size_t;
+
+// ---- mcpp-index compat shim 2/2: Clang-on-Windows fix ---------------------
+// ut.hpp line 687 is `#if defined(_MSC_VER)` and references the MSVC
+// builtins `__argc` / `__argv`. Clang on the MSVC ABI (x86_64-windows-msvc)
+// sets `_MSC_VER` but does NOT provide those builtins — the neighboring
+// upstream guards at lines 291 / 311 / 1147 already gate clang out, but
+// line 687 missed it. Provide macros as stand-ins (cfg::largc is reassigned
+// from main() args at runtime anyway, so the value is unused). MSVC itself
+// never enters this guard, so its real builtins are untouched.
+#if defined(_MSC_VER) and defined(__clang__)
+  #define __argc 0
+  #define __argv ((const char**)nullptr)
+#endif
+
+#define BOOST_UT_CXX_MODULES 1
+#include "ut.hpp"
+
+#if defined(_MSC_VER) and defined(__clang__)
+  #undef __argc
+  #undef __argv
+#endif
+]==],
+        },
+        sources      = { "mcpp_generated/boost.ut.cppm" },
+        targets      = { ["boost_ut"] = { kind = "lib" } },
+        deps         = { },
+    },
+}

tests/examples/boost-ext.ut/mcpp.toml

@@ -0,0 +1,15 @@
+# boost-ext.ut test project: consumes the C++23 module `boost.ut` and
+# asserts two test styles (UDL + function syntax) plus an expect failure
+# under `mcpp test`.
+# Overrides the workspace-root redirect (`compat`): this member needs the
+# `boost-ext` namespace. A member-level [indices] REPLACES the inherited
+# table rather than merging with it — keeps the project index repo to ONE.
+[indices]
+boost-ext = { path = "../../.." }
+
+[package]
+name = "boost-ext-ut-tests"
+version = "0.1.0"
+
+[dependencies.boost-ext]
+ut = "2.3.1"

tests/examples/boost-ext.ut/tests/ut.cpp

@@ -0,0 +1,23 @@
+// Behavioral test: build two tests under [Boost::ext].UT via `import boost.ut;`,
+// then exercise the UDL ("..."_test) and function-call (test("...")) syntaxes.
+// Counts test registration by reading ut's `tests_runner` directly is awkward,
+// so the test instead just RUNS a passing assertion in each style; if the
+// module fails to import or any expect() fails, [Boost::ext].UT reports the
+// failure through its test runner and `mcpp test` returns non-zero.
+import std;
+import boost.ut;
+
+using namespace boost::ut;
+
+int main() {
+    "UDL syntax"_test = [] {
+        expect(42_i == 42);
+    };
+
+    test("function syntax") = [] {
+        expect(0_i == 0);
+        expect(1u == 1_u);
+    };
+
+    return 0;
+}