Require numpy for the plugin tests in CI

.github/workflows/unit_tests.yml

@@ -44,6 +44,14 @@ jobs:
         uses: actions/download-artifact@v8
         with:
           name: ${{ inputs.artifact }}
+      # run_unit_tests.sh installs the plugin tests' numpy with the uv the build stages
+      # beside them; the Windows arm64 build bundles none, so put one on PATH there.
+      - name: Install uv
+        if: runner.os == 'Windows' && runner.arch == 'ARM64'
+        uses: astral-sh/setup-uv@v10.2.0
+        with:
+          version: "0.11.21"  # ORCA_UV_VERSION in CMakeLists.txt
+          enable-cache: false
       - uses: lukka/get-cmake@latest
         with:
           cmakeVersion: "~4.3.0"  # use most recent 4.3.x version

.gitignore

@@ -52,4 +52,6 @@ internal_docs/
 __pycache__/
 *.pyc
 *.opc
-docs/superpowers/
+/.test/
+docs/superpowers/
+ctest_results.xml

scripts/run_unit_tests.sh

@@ -2,7 +2,8 @@
 
 # This file is made to support the unit tests workflow.
 # It should only require the directories build/tests, scripts/, and tests/ to function,
-# and cmake (with ctest) installed.
+# and cmake (with ctest) installed -- plus network access to PyPI whenever numpy has to
+# be installed into a freshly built test tree (see below).
 # (otherwise, update the workflow too, but try to avoid to keep things self-contained)
 #
 # Usage: run_unit_tests.sh [TEST_DIR] [BUILD_CONFIG]
@@ -18,6 +19,52 @@ cd "${ROOT_DIR}" || exit 1
 TEST_DIR="${1:-build/tests}"
 BUILD_CONFIG="${2:-}"
 
+# The slic3rutils plugin-host tests build numpy arrays through the CPython copied next
+# to the test binary (see tests/slic3rutils/CMakeLists.txt), which ships no numpy.
+# Install it with the uv staged beside that runtime -- the tool the app installs plugin
+# dependencies with -- straight into the interpreter's own site-packages: no pip needed
+# in the runtime, no PYTHONPATH. Re-checked every run because a rebuild of the test
+# target re-copies the runtime; needs network whenever it installs. Pinned so a numpy
+# release cannot change results on its own.
+NUMPY_VERSION="2.5.3"
+
+# Without numpy those tests assert the numpy-absent error path instead, so a local run
+# only warns. Under CI it fails the run, which would otherwise stay green while silently
+# dropping the array coverage. (The Flatpak leg runs this inside `flatpak build`, whose
+# minimal environment has no CI, and its offline build stages no uv, so numpy stays
+# best-effort there.)
+numpy_unavailable() {
+    if [ -n "${CI:-}" ]; then
+        echo "error: $1" >&2
+        exit 1
+    fi
+    echo "warning: $1; the numpy-backed binding tests will cover only the numpy-absent path."
+}
+
+has_pinned_numpy() {
+    "${python_exe}" -c "import sys, numpy; sys.exit(numpy.__version__ != '${NUMPY_VERSION}')" >/dev/null 2>&1
+}
+
+find_args=("${TEST_DIR}" \( -path '*/python/bin/python3' -o -path '*/python/python.exe' \))
+# Multi-config trees hold one copy per configuration; only bootstrap the one being run.
+[ -n "${BUILD_CONFIG}" ] && find_args+=(-path "*/${BUILD_CONFIG}/*")
+python_exe="$(find "${find_args[@]}" -print -quit 2>/dev/null)"
+
+if [ -z "${python_exe}" ]; then
+    numpy_unavailable "no bundled Python under ${TEST_DIR}"
+elif ! has_pinned_numpy; then
+    uv_exe="${python_exe%/python/*}/tools/uv/uv"
+    # Builds that bundle no uv (Windows arm64) fall back to one on PATH.
+    [ -x "${uv_exe}" ] || uv_exe="$(command -v uv)"
+    echo "Installing numpy ${NUMPY_VERSION} into the embedded test interpreter (${python_exe})..."
+    if [ -z "${uv_exe}" ]; then
+        numpy_unavailable "no uv staged beside the tests or on PATH"
+    elif ! "${uv_exe}" pip install --python "${python_exe}" --only-binary :all: "numpy==${NUMPY_VERSION}" \
+            || ! has_pinned_numpy; then
+        numpy_unavailable "could not install numpy ${NUMPY_VERSION} into ${python_exe}"
+    fi
+fi
+
 # Run the whole suite, excluding tests tagged [NotWorking] and tests labelled RequiresApp,
 # which run the built orca-slicer binary that this directory does not contain.
 # --no-tests=error fails the job if the filter matches nothing (instead of passing green).

src/libslic3r/Format/3mf.cpp

@@ -307,17 +307,14 @@ bool PrusaFileParser::check_3mf_from_prusa(const std::string filename)
 
             mz_zip_archive_file_stat stat;
             if (!mz_zip_reader_file_stat(&archive, model_file_index, &stat)) goto EXIT;
-            // expat sizes its buffer with an int, so a larger entry cannot be parsed in one piece.
-            if (stat.m_uncomp_size > static_cast<mz_uint64>(std::numeric_limits<int>::max())) goto EXIT;
 
-            const int xml_size = static_cast<int>(stat.m_uncomp_size);
-            void *parser_buffer = XML_GetBuffer(m_parser, xml_size);
+            void *parser_buffer = XML_GetBuffer(m_parser, (int) stat.m_uncomp_size);
             if (parser_buffer == nullptr) goto EXIT;
 
-            mz_bool res = mz_zip_reader_extract_file_to_mem(&archive, stat.m_filename, parser_buffer, static_cast<size_t>(xml_size), 0);
+            mz_bool res = mz_zip_reader_extract_file_to_mem(&archive, stat.m_filename, parser_buffer, (size_t) stat.m_uncomp_size, 0);
             if (res == 0) goto EXIT;
 
-            XML_ParseBuffer(m_parser, xml_size, 1);
+            XML_ParseBuffer(m_parser, (int) stat.m_uncomp_size, 1);
         }
     }
 
@@ -1349,26 +1346,19 @@ ModelVolumeType type_from_string(const std::string &s)
         XML_SetUserData(m_xml_parser, (void*)this);
         XML_SetElementHandler(m_xml_parser, _3MF_Importer::_handle_start_config_xml_element, _3MF_Importer::_handle_end_config_xml_element);
 
-        // expat sizes its buffer with an int, so a larger entry cannot be parsed in one piece.
-        if (stat.m_uncomp_size > static_cast<mz_uint64>(std::numeric_limits<int>::max())) {
-            add_error("Found invalid size");
-            return false;
-        }
-        const int xml_size = static_cast<int>(stat.m_uncomp_size);
-
-        void* parser_buffer = XML_GetBuffer(m_xml_parser, xml_size);
+        void* parser_buffer = XML_GetBuffer(m_xml_parser, (int)stat.m_uncomp_size);
         if (parser_buffer == nullptr) {
             add_error("Unable to create buffer");
             return false;
         }
 
-        mz_bool res = mz_zip_reader_extract_file_to_mem(&archive, stat.m_filename, parser_buffer, static_cast<size_t>(xml_size), 0);
+        mz_bool res = mz_zip_reader_extract_file_to_mem(&archive, stat.m_filename, parser_buffer, (size_t)stat.m_uncomp_size, 0);
         if (res == 0) {
             add_error("Error while reading config data to buffer");
             return false;
         }
 
-        if (!XML_ParseBuffer(m_xml_parser, xml_size, 1)) {
+        if (!XML_ParseBuffer(m_xml_parser, (int)stat.m_uncomp_size, 1)) {
             char error_buf[1024];
             ::sprintf(error_buf, "Error (%s) while parsing xml file at line %d", XML_ErrorString(XML_GetErrorCode(m_xml_parser)), (int)XML_GetCurrentLineNumber(m_xml_parser));
             add_error(error_buf);

src/libslic3r/Format/bbs_3mf.cpp

@@ -2508,26 +2508,19 @@ void PlateData::parse_filament_info(GCodeProcessorResult *result)
         XML_SetEntityDeclHandler(m_xml_parser, nullptr);
         XML_SetExternalEntityRefHandler(m_xml_parser, nullptr);
 
-        // expat sizes its buffer with an int, so a larger entry cannot be parsed in one piece.
-        if (stat.m_uncomp_size > static_cast<mz_uint64>(std::numeric_limits<int>::max())) {
-            add_error("Found invalid size");
-            return false;
-        }
-        const int xml_size = static_cast<int>(stat.m_uncomp_size);
-
-        void* parser_buffer = XML_GetBuffer(m_xml_parser, xml_size);
+        void* parser_buffer = XML_GetBuffer(m_xml_parser, (int)stat.m_uncomp_size);
         if (parser_buffer == nullptr) {
             add_error("Unable to create buffer");
             return false;
         }
 
-        mz_bool res = mz_zip_reader_extract_file_to_mem(&archive, stat.m_filename, parser_buffer, static_cast<size_t>(xml_size), 0);
+        mz_bool res = mz_zip_reader_extract_file_to_mem(&archive, stat.m_filename, parser_buffer, (size_t)stat.m_uncomp_size, 0);
         if (res == 0) {
             add_error("Error while reading config data to buffer");
             return false;
         }
 
-        if (!XML_ParseBuffer(m_xml_parser, xml_size, 1)) {
+        if (!XML_ParseBuffer(m_xml_parser, (int)stat.m_uncomp_size, 1)) {
             char error_buf[1024];
             ::snprintf(error_buf, 1024, "Error (%s) while parsing xml file at line %d", XML_ErrorString(XML_GetErrorCode(m_xml_parser)), (int)XML_GetCurrentLineNumber(m_xml_parser));
             add_error(error_buf);

src/slic3r/Utils/PrintHost.cpp

@@ -6,6 +6,7 @@
 #include <boost/optional.hpp>
 #include <boost/log/trivial.hpp>
 #include <boost/filesystem.hpp>
+#include <nlohmann/json.hpp>
 
 #include <wx/string.h>
 #include <wx/app.h>
@@ -115,10 +116,67 @@ std::string PrintHost::get_print_host_webui(DynamicPrintConfig* config)
     return webui_url;
 }
 
+namespace {
+
+// Moonraker (Klipper's API server) reports a raised exception as { "error": { "code", "message", "traceback" } }
+// under every host type that connects to it, often with the cause only in the traceback. Returns the reason to show,
+// or empty for any other body.
+std::string moonraker_error_reason(const std::string &body)
+{
+    const auto root = nlohmann::json::parse(body, nullptr, false);
+    const auto err  = root.find("error");
+    if (err == root.end())
+        return {};
+    const auto message   = err->find("message");
+    const auto traceback = err->find("traceback");
+    if (message == err->end() || traceback == err->end() || !message->is_string() || !traceback->is_string())
+        return {};
+
+    const auto &msg = message->get_ref<const std::string &>();
+    const auto &tb  = traceback->get_ref<const std::string &>();
+    if (msg.empty())
+        return {};
+    const auto end = tb.find_last_not_of(" \t\r\n");
+    if (end == std::string::npos)
+        return msg;
+
+    // Chained exceptions each start a new traceback; the one that failed the request is the last.
+    const auto header = tb.rfind("Traceback (most recent call last):", end);
+
+    // Tornado renders a raised HTTPError as "HTTP <code>: <reason>[ (<detail>)]", and the detail may span lines.
+    const auto code = err->find("code");
+    if (code != err->end() && code->is_number_integer()) {
+        const std::string marker = "HTTP " + std::to_string(code->get<int>()) + ": ";
+        const auto        pos    = tb.rfind(marker, end);
+        if (pos != std::string::npos && (header == std::string::npos || pos > header) && pos + marker.size() <= end) {
+            const std::string reason = tb.substr(pos + marker.size(), end + 1 - pos - marker.size());
+            // An HTTPError whose detail equals its reason, like HTTPError(401, "Unauthorized"), renders the phrase twice.
+            return reason == msg + " (" + msg + ")" ? msg : reason;
+        }
+    }
+
+    // Any other exception's type and message are everything from the first unindented line after its frames.
+    auto begin = (header == std::string::npos) ? std::string::npos : tb.find('\n', header);
+    while (begin != std::string::npos && begin < end) {
+        ++begin;
+        if (tb[begin] != ' ' && tb[begin] != '\r' && tb[begin] != '\n')
+            break;
+        begin = tb.find('\n', begin);
+    }
+    if (begin == std::string::npos || begin > end) {
+        const auto nl = tb.rfind('\n', end);
+        begin         = (nl == std::string::npos) ? 0 : nl + 1;
+    }
+    return msg + " (" + tb.substr(begin, end + 1 - begin) + ")";
+}
+
+} // namespace
+
 wxString PrintHost::format_error(const std::string &body, const std::string &error, unsigned status) const
 {
     if (status != 0) {
-        auto wxbody = wxString::FromUTF8(body.data());
+        const std::string reason = moonraker_error_reason(body);
+        auto wxbody = wxString::FromUTF8(reason.empty() ? body : reason);
         return wxString::Format("HTTP %u: %s", status, wxbody);
     } else {
         if (error.find("curl:Timeout was reached") != std::string::npos) {

src/slic3r/plugin/PythonInterpreter.cpp

@@ -345,16 +345,21 @@ boost::filesystem::path find_bundled_python_home()
     fs::path bundle_python = fs::path(resources_dir()).parent_path() / "MacOS" / "python";
     if (valid_python_home(bundle_python))
         return bundle_python;
-#elif defined(_WIN32)
-    fs::path exe_python = boost::dll::program_location().parent_path() / "python";
-    if (valid_python_home(exe_python))
-        return exe_python;
-#else
+#elif !defined(_WIN32)
     fs::path linux_python = fs::path(resources_dir()).parent_path() / "lib" / "python";
     if (valid_python_home(linux_python))
         return linux_python;
 #endif
 
+    // Next to the executable: the Windows install layout, and the runtime copied
+    // beside every platform's unit-test binary (tests/slic3rutils/CMakeLists.txt).
+    // The CI test runner only receives the build/tests tree, so the candidates
+    // below -- all of which point into the deps or install trees -- never resolve
+    // there.
+    fs::path exe_python = boost::dll::program_location().parent_path() / "python";
+    if (valid_python_home(exe_python))
+        return exe_python;
+
     fs::path configured_python = ORCA_BUNDLED_PYTHON_ROOT;
     if (!configured_python.empty() && valid_python_home(configured_python))
         return configured_python;

tests/libslic3r/test_3mf.cpp

@@ -17,7 +17,6 @@
 #include <nlohmann/json.hpp>
 
 #include <boost/filesystem/operations.hpp>
-#include <boost/nowide/fstream.hpp>
 #include <boost/algorithm/string/predicate.hpp>
 #include <algorithm>
 
@@ -1462,79 +1461,3 @@ SCENARIO("bbs_3mf_is_published detects only genuinely published 3MFs", "[3mf]")
     }
 }
 
-// Writes a single-entry zip whose central directory carries a zip64 record declaring an
-// uncompressed size beyond what the 32-bit expat buffer API can take, while the deflated
-// payload inflates to only ~64 KiB. Built by hand because miniz never writes a size that
-// disagrees with the data.
-static void write_zip_with_oversized_entry(const std::string& path, const std::string& entry)
-{
-    const std::string xml = "<?xml version=\"1.0\"?><!--" + std::string(65536, 'A') + "--><a/>";
-    size_t comp_len = 0;
-    void*  comp     = tdefl_compress_mem_to_heap(xml.data(), xml.size(), &comp_len, TDEFL_DEFAULT_MAX_PROBES);
-    REQUIRE(comp != nullptr);
-    const std::string deflated(static_cast<const char*>(comp), comp_len);
-    mz_free(comp);
-    const uint32_t crc = static_cast<uint32_t>(mz_crc32(MZ_CRC32_INIT, reinterpret_cast<const unsigned char*>(xml.data()), xml.size()));
-    const uint64_t claimed_size = (uint64_t(1) << 32) + 16;
-
-    std::string out;
-    auto put = [&out](uint64_t v, int bytes) {
-        for (int i = 0; i < bytes; ++i)
-            out.push_back(static_cast<char>((v >> (8 * i)) & 0xFF));
-    };
-    // local file header, with the true sizes
-    put(0x04034b50, 4); put(45, 2); put(0, 2); put(8, 2); put(0, 2); put(0, 2);
-    put(crc, 4); put(deflated.size(), 4); put(xml.size(), 4); put(entry.size(), 2); put(0, 2);
-    out += entry + deflated;
-    // central directory header, sizes deferred to the zip64 extra field
-    const size_t cd_offset = out.size();
-    put(0x02014b50, 4); put(45, 2); put(45, 2); put(0, 2); put(8, 2); put(0, 2); put(0, 2);
-    put(crc, 4); put(0xFFFFFFFF, 4); put(0xFFFFFFFF, 4); put(entry.size(), 2); put(20, 2);
-    put(0, 2); put(0, 2); put(0, 2); put(0, 4); put(0, 4);
-    out += entry;
-    put(0x0001, 2); put(16, 2); put(claimed_size, 8); put(deflated.size(), 8);
-    const size_t cd_size = out.size() - cd_offset;
-    // end of central directory
-    put(0x06054b50, 4); put(0, 2); put(0, 2); put(1, 2); put(1, 2);
-    put(cd_size, 4); put(cd_offset, 4); put(0, 2);
-
-    boost::nowide::ofstream f(path, std::ios::binary);
-    REQUIRE(f.good());
-    f.write(out.data(), static_cast<std::streamsize>(out.size()));
-    REQUIRE(f.good());
-}
-
-TEST_CASE("3MF XML entries declaring more than an int can hold fail to load", "[3mf]") {
-    ScopedTemporaryFile temp(".3mf");
-    const std::string   path = temp.string();
-
-    SECTION("BBS importer") {
-        write_zip_with_oversized_entry(path, "_rels/.rels");
-        Model                     model;
-        DynamicPrintConfig        config;
-        ConfigSubstitutionContext ctxt{ForwardCompatibilitySubstitutionRule::Enable};
-        PlateDataPtrs             plates;
-        std::vector<Preset*>      project_presets;
-        bool                      is_bbl_3mf = false, is_orca_3mf = false;
-        Semver                    file_version;
-        bool                      loaded = true;
-        REQUIRE_NOTHROW(loaded = load_bbs_3mf(path.c_str(), &config, &ctxt, &model, &plates, &project_presets, &is_bbl_3mf,
-                                              &is_orca_3mf, &file_version, nullptr, LoadStrategy::LoadModel | LoadStrategy::LoadConfig));
-        CHECK_FALSE(loaded);
-        release_PlateData_list(plates);
-    }
-    SECTION("PrusaSlicer importer") {
-        write_zip_with_oversized_entry(path, "Metadata/Slic3r_PE_model.config");
-        Model                     model;
-        DynamicPrintConfig        config;
-        ConfigSubstitutionContext ctxt{ForwardCompatibilitySubstitutionRule::Disable};
-        bool                      loaded = true;
-        REQUIRE_NOTHROW(loaded = load_3mf(path.c_str(), config, ctxt, &model, false));
-        CHECK_FALSE(loaded);
-    }
-    SECTION("PrusaSlicer fingerprint probe") {
-        write_zip_with_oversized_entry(path, "3D/3dmodel.model");
-        PrusaFileParser parser;
-        CHECK_FALSE(parser.check_3mf_from_prusa(path));
-    }
-}

tests/slic3rutils/CMakeLists.txt

@@ -18,6 +18,7 @@ add_executable(${_TEST_NAME}_tests
     test_plugin_install.cpp
     test_plugin_lifecycle.cpp
     test_plugin_printer_agent.cpp
+    test_printhost.cpp
     test_slicing_pipeline_bindings.cpp
     test_slicing_pipeline_config.cpp
     test_plugin_sort.cpp
@@ -48,9 +49,16 @@ if (WIN32)
         COMMENT "Copying Python runtime for slic3rutils plugin host API tests"
         VERBATIM
     )
-elseif (APPLE)
-    target_link_options(${_TEST_NAME}_tests PRIVATE
-        "LINKER:-rpath,@executable_path/python/lib")
+elseif (NOT FLATPAK)
+    # The CI unit-test runner only receives the build/tests tree, so both the
+    # interpreter and the libpython the test binary links have to travel next to
+    # the executable; find_bundled_python_home() picks the copy up from there.
+    if (APPLE)
+        target_link_options(${_TEST_NAME}_tests PRIVATE
+            "LINKER:-rpath,@executable_path/python/lib")
+    else ()
+        set_property(TARGET ${_TEST_NAME}_tests APPEND PROPERTY BUILD_RPATH "$ORIGIN/python/lib")
+    endif ()
 
     add_custom_command(TARGET ${_TEST_NAME}_tests POST_BUILD
         COMMAND ${CMAKE_COMMAND} -E rm -rf
@@ -58,7 +66,7 @@ elseif (APPLE)
         COMMAND ${CMAKE_COMMAND} -E copy_directory
             "${CMAKE_PREFIX_PATH}/libpython"
             "$<TARGET_FILE_DIR:${_TEST_NAME}_tests>/python"
-        COMMENT "Copying Python runtime for macOS plugin host API tests"
+        COMMENT "Copying Python runtime for the plugin host API tests"
         VERBATIM
     )
 elseif (FLATPAK)
@@ -75,4 +83,16 @@ elseif (FLATPAK)
     )
 endif()
 
+# scripts/run_unit_tests.sh installs the tests' numpy into that runtime with this uv,
+# staged where the app build tree keeps it (<exe dir>/tools/uv, see src/CMakeLists.txt).
+if (ORCA_BUNDLED_UV_EXECUTABLE)
+    add_custom_command(TARGET ${_TEST_NAME}_tests POST_BUILD
+        COMMAND ${CMAKE_COMMAND} -E make_directory "$<TARGET_FILE_DIR:${_TEST_NAME}_tests>/tools/uv"
+        COMMAND ${CMAKE_COMMAND} -E copy_if_different "${ORCA_BUNDLED_UV_EXECUTABLE}"
+            "$<TARGET_FILE_DIR:${_TEST_NAME}_tests>/tools/uv/${ORCA_BUNDLED_UV_FILENAME}"
+        COMMENT "Copying uv for the plugin host API tests"
+        VERBATIM
+    )
+endif()
+
 orcaslicer_discover_tests(${_TEST_NAME}_tests)

tests/slic3rutils/test_printhost.cpp

@@ -0,0 +1,213 @@
+#include <catch2/catch_all.hpp>
+
+#include <nlohmann/json.hpp>
+
+#include "slic3r/Utils/PrintHost.hpp"
+
+using namespace Slic3r;
+
+namespace {
+
+class TestPrintHost : public PrintHost
+{
+public:
+    using PrintHost::format_error;
+
+    const char* get_name() const override { return "Test"; }
+    bool test(wxString&) const override { return true; }
+    wxString get_test_ok_msg() const override { return {}; }
+    wxString get_test_failed_msg(wxString&) const override { return {}; }
+    bool upload(PrintHostUpload, ProgressFn, ErrorFn, InfoFn) const override { return true; }
+    bool has_auto_discovery() const override { return false; }
+    bool can_test() const override { return false; }
+    PrintHostPostUploadActions get_post_upload_actions() const override { return {}; }
+    std::string get_host() const override { return {}; }
+};
+
+std::string format_error(const std::string& body, const std::string& error, unsigned status)
+{
+    return TestPrintHost().format_error(body, error, status).ToStdString();
+}
+
+std::string envelope(int code, const std::string& message, const std::string& traceback)
+{
+    return nlohmann::json{{"error", {{"code", code}, {"message", message}, {"traceback", traceback}}}}.dump();
+}
+
+std::string moonraker_error(int code, const std::string& message, const std::string& detail = {})
+{
+    std::string line = "tornado.web.HTTPError: HTTP " + std::to_string(code) + ": " + message;
+    if (!detail.empty())
+        line += " (" + detail + ")";
+    return envelope(code, message, "Traceback (most recent call last):\n  ...\n" + line + "\n");
+}
+
+// A real Moonraker body for uploading a file that is being printed.
+constexpr const char* k_busy_file_403 =
+    R"JSON({"error": {"code": 403, "message": "Forbidden", "traceback": "Traceback (most recent call last):\n\n  File \"/home/lava/moonraker/moonraker/components/file_manager/file_manager.py\", line 1017, in _finish_gcode_upload\n    can_start = self._handle_operation_check(check_path)\n                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^\n\nmoonraker.utils.exceptions.ServerError: File currently in use\n\nDuring handling of the above exception, another exception occurred:\n\nTraceback (most recent call last):\n\n  File \"/home/lava/moonraker/moonraker/components/application.py\", line 1069, in post\n    raise tornado.web.HTTPError(\ntornado.web.HTTPError: HTTP 403: Forbidden (File is loaded, upload not permitted)\n"}})JSON";
+
+} // namespace
+
+TEST_CASE("A Klipper upload error shows its reason instead of a Python traceback", "[PrintHost][Regression]")
+{
+    const std::string msg = format_error(k_busy_file_403, "", 403);
+    INFO("actual: " << msg);
+
+    CHECK(msg == "HTTP 403: Forbidden (File is loaded, upload not permitted)");
+    CHECK_THAT(msg, !Catch::Matchers::ContainsSubstring("Traceback"));
+    CHECK_THAT(msg, !Catch::Matchers::ContainsSubstring("file_manager.py"));
+}
+
+TEST_CASE("The specific cause is recovered from a file endpoint's traceback", "[PrintHost]")
+{
+    SECTION("a plain detail")
+    {
+        const std::string body = moonraker_error(403, "Forbidden", "File is loaded, upload not permitted");
+        CHECK(format_error(body, "", 403) == "HTTP 403: Forbidden (File is loaded, upload not permitted)");
+    }
+
+    SECTION("a detail whose own parentheses nest (a filename)")
+    {
+        const std::string detail = "Directory does not exist (/home/pi/gcodes/plate (1).gcode)";
+        const std::string body   = moonraker_error(400, "Bad Request", detail);
+        CHECK(format_error(body, "", 400) == "HTTP 400: Bad Request (" + detail + ")");
+    }
+
+    SECTION("a detail that contains the reason phrase")
+    {
+        const std::string body = moonraker_error(403, "Forbidden", "Forbidden zone: access denied");
+        CHECK(format_error(body, "", 403) == "HTTP 403: Forbidden (Forbidden zone: access denied)");
+    }
+
+    SECTION("a detail that spans lines")
+    {
+        const std::string detail = "Move out of range\nX=250.000 Y=10.000";
+        const std::string body   = moonraker_error(400, "Bad Request", detail);
+        CHECK(format_error(body, "", 400) == "HTTP 400: Bad Request (" + detail + ")");
+    }
+
+    SECTION("a detail that only repeats the reason phrase is dropped")
+    {
+        const std::string body = moonraker_error(401, "Unauthorized", "Unauthorized");
+        CHECK(format_error(body, "", 401) == "HTTP 401: Unauthorized");
+    }
+}
+
+TEST_CASE("An unhandled exception shows its type and message", "[PrintHost]")
+{
+    const std::string frame = "Traceback (most recent call last):\n"
+                              "  File \"/home/pi/moonraker/moonraker/components/file_manager/file_manager.py\", line 1, in write\n"
+                              "    self._write(data)\n";
+
+    SECTION("a one-line message")
+    {
+        const std::string body = envelope(500, "Internal Server Error", frame + "OSError: [Errno 28] No space left on device\n");
+        CHECK(format_error(body, "", 500) == "HTTP 500: Internal Server Error (OSError: [Errno 28] No space left on device)");
+    }
+
+    SECTION("a message that spans lines")
+    {
+        const std::string body = envelope(500, "Internal Server Error", frame + "ServerError: Klippy request failed\n  see klippy.log\n");
+        CHECK(format_error(body, "", 500) == "HTTP 500: Internal Server Error (ServerError: Klippy request failed\n  see klippy.log)");
+    }
+
+    SECTION("raised while handling an HTTPError with the same code")
+    {
+        const std::string traceback = frame + "tornado.web.HTTPError: HTTP 500: Internal Server Error (Database locked)\n\n"
+                                              "During handling of the above exception, another exception occurred:\n\n" +
+                                      frame + "OSError: [Errno 5] Input/output error\n";
+        const std::string body      = envelope(500, "Internal Server Error", traceback);
+        CHECK(format_error(body, "", 500) == "HTTP 500: Internal Server Error (OSError: [Errno 5] Input/output error)");
+    }
+
+    SECTION("a traceback with no header")
+    {
+        const std::string body = envelope(500, "Internal Server Error", "OSError: [Errno 5] Input/output error");
+        CHECK(format_error(body, "", 500) == "HTTP 500: Internal Server Error (OSError: [Errno 5] Input/output error)");
+    }
+}
+
+TEST_CASE("A reason already complete in message is shown unchanged", "[PrintHost]")
+{
+    SECTION("message is the whole reason, no trailing detail")
+    {
+        const std::string body = moonraker_error(503, "Klippy is not ready");
+        CHECK(format_error(body, "", 503) == "HTTP 503: Klippy is not ready");
+    }
+
+    SECTION("a message that itself contains parentheses is not duplicated")
+    {
+        const std::string reason = "Requested blocks (0-5) are unavailable";
+        const std::string body   = moonraker_error(400, reason);
+        CHECK(format_error(body, "", 400) == "HTTP 400: " + reason);
+    }
+}
+
+TEST_CASE("A Moonraker error with no usable detail shows just the reason phrase", "[PrintHost]")
+{
+    struct Case
+    {
+        const char* name;
+        const char* body;
+        unsigned status;
+        const char* expected;
+    };
+
+    const auto c = GENERATE(
+        Case{"an empty traceback", R"JSON({"error": {"code": 500, "message": "Internal Server Error", "traceback": ""}})JSON", 500,
+             "HTTP 500: Internal Server Error"},
+        Case{"a traceback of only whitespace", R"JSON({"error": {"code": 500, "message": "Internal Server Error", "traceback": "\n \n"}})JSON",
+             500, "HTTP 500: Internal Server Error"});
+
+    DYNAMIC_SECTION(c.name) { CHECK(format_error(c.body, "", c.status) == c.expected); }
+}
+
+TEST_CASE("A percent sign in the reason is not a format specifier", "[PrintHost]")
+{
+    const std::string body = moonraker_error(507, "Insufficient Storage", "disk 100% full");
+    CHECK(format_error(body, "", 507) == "HTTP 507: Insufficient Storage (disk 100% full)");
+}
+
+TEST_CASE("Error bodies that are not a Moonraker envelope are left unchanged", "[PrintHost]")
+{
+    SECTION("OctoPrint's string-valued error member")
+    {
+        const std::string body = R"JSON({"error": "File not found"})JSON";
+        CHECK(format_error(body, "", 404) == "HTTP 404: " + body);
+    }
+
+    SECTION("PrusaLink's top-level message, not under error")
+    {
+        const std::string body = R"JSON({"title": "Conflict", "message": "Printer is printing"})JSON";
+        CHECK(format_error(body, "", 409) == "HTTP 409: " + body);
+    }
+
+    SECTION("a body that is not JSON")
+    {
+        const std::string html = "<html><head><title>502 Bad Gateway</title></head></html>";
+        CHECK(format_error(html, "", 502) == "HTTP 502: " + html);
+    }
+
+    SECTION("an error object with no traceback")
+    {
+        const std::string body = R"JSON({"error": {"code": 500, "message": "Internal Server Error"}})JSON";
+        CHECK(format_error(body, "", 500) == "HTTP 500: " + body);
+    }
+
+    SECTION("an error object whose traceback is null")
+    {
+        const std::string body = R"JSON({"error": {"code": 500, "message": "Internal Server Error", "traceback": null}})JSON";
+        CHECK(format_error(body, "", 500) == "HTTP 500: " + body);
+    }
+
+    SECTION("an envelope whose reason phrase is empty")
+    {
+        const std::string body = envelope(403, "", "Traceback (most recent call last):\nOSError: denied\n");
+        CHECK(format_error(body, "", 403) == "HTTP 403: " + body);
+    }
+
+    SECTION("a transport error with no HTTP status")
+    {
+        CHECK(format_error("", "curl:Could not connect", 0) == "curl:Could not connect");
+    }
+}