flatpak: run host interpreters via flatpak-spawn; validation --mode flag

py_func, lua_func and the run item now reach host binaries through
`flatpak-spawn --host` instead of trying to load them under the
sandbox runtime (which fails with a glibc ABI mismatch). Adds
`--talk-name=org.freedesktop.Flatpak` to the manifest, stages the
/app/lib/testium tree under /tmp so the host can read it, and drops
the dead `_FLATPAK_HOST_DIRS` / lib-injection code paths that the
new approach makes obsolete.

Validation suite gains a `--mode source|wheel|pyinstaller|flatpak|
appimage` flag so the same item set can run against every packaging
channel; per-mode report file names avoid clobbering.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

DESIGN.md

@@ -114,11 +114,20 @@ To add a new API call usable from subprocesses:
 ### External interpreter resolution (`bins.py`)
 `src/testium/interpreter/utils/bins.py` — single source of truth for the paths to the external Python and Lua interpreters used by subprocesses.
 
-- `python_bin()` / `lua_bin()` : resolve once, cache in memory. User can override via the `python_bin` / `lua_bin` global dict keys (typically populated from the YAML config). Falls back to discovery on PATH (candidates: `python3`/`python` and `lua`/`lua5.5`/`lua5.4`/`lua5.3`/`lua5.2`/`lua5.1`).
+- `python_bin()` / `lua_bin()` : resolve and cache. The cache is keyed by `(name, override)` so that a later change to `gd[python_bin]` (typically when a `param.yaml` sets the key) triggers a re-resolution on the next lookup instead of returning the stale auto-discovered path. Falls back to discovery on PATH (candidates: `python3`/`python` and `lua`/`lua5.5`/`lua5.4`/`lua5.3`/`lua5.2`/`lua5.1`).
 - `ensure(*names)` : called by `TestSet._validate_runtime_deps()` at test load. Always requires `python` (the eval engine always runs); requires `lua` only if a `lua_func` item is in the tree. Fails fast with a clear error citing tried candidates and override key.
 
 Engines (`PyProcessBase`, `LuaProcessBase`, `EvalExecEngine`) call `bins.python_bin()`/`bins.lua_bin()` themselves — call sites never pass an explicit binary path.
 
+#### Override-timing contract (`apply_overrides`)
+`bins.python_bin()` is called for the **first** time inside `eval_process_init()` (the long-lived inline-`<| … |>` subprocess), which happens **before** the YAML param files are loaded. To make `-d python_bin=…` and the GUI `python_bin` preference take effect for `eval_proc` itself, `process.py:run()` applies them to gd **before** `eval_process_init()` via the `apply_overrides()` helper extracted from `update_global()`. The post-load `update_global()` call then re-applies the same overrides (after `prepare_global()` clears gd), keeping the gd value in sync with the cached resolution.
+
+| Override source | `eval_proc` | `py_func` / `cycle` / `post_exec` |
+|---|---|---|
+| `-d python_bin=…` (CLI) | ✅ | ✅ |
+| GUI `python_bin` preference | ✅ | ✅ |
+| `python_bin: …` in `param.yaml` | ❌ (eval_proc already started) | ✅ (cache re-resolves on key change) |
+
 ## Key files
 
 | Path | Role |
@@ -261,12 +270,18 @@ Both Flatpak and AppImage export `TESTIUM_VERSION` from a launcher (Flatpak: lau
 - `unittest` item: renamed from `unittest_file`.
 - GUI test tree: check and fold state preserved across same-file reloads.
 - Licence: EUPL-1.2.
+- Interpreter override timing: `apply_overrides()` extracted from `update_global()` and called by `process.py:run()` before `eval_process_init()`, so `-d python_bin=…` / GUI prefs reach `bins.python_bin()` on its first lookup. `bins._resolve()` cache is now keyed by `(name, override)` so later `param.yaml` changes are picked up by subsequently constructed engines.
 
 ## Validation tests
-Located in `test/validation/`. Run with `-b` flag:
+Located in `test/validation/`. Two entry points:
 ```
-./run.sh -b -- test/validation/main.tum
+./test/validation/run.sh        # wrapper — uses a dedicated venv (see below)
+./run.sh -b -- test/validation/main.tum   # direct — testium's own python is used for test execution
 ```
+The `run.sh` / `run.bat` wrappers create a dedicated Python venv at `${TMPDIR:-/tmp}/testium-validation-venv` (Linux) or `%TEMP%\testium-validation-venv` (Windows), with `--system-site-packages` + `pip install junit-xml`, and run the suite with `-d python_bin=…` so every test-execution subprocess (eval_proc, py_func, cycle, post_exec) runs inside the venv. testium itself keeps running in the project's own environment. `clean` as the first argument recreates the venv.
+
+The `venv` item (`test/validation/items/venv/`) asserts that the override actually took effect: `python_bin` is set, `sys.executable` matches it, `sys.prefix == dirname(dirname(python_bin))`, and `sys.prefix != sys.base_prefix` (the last marker catches the case where `python_bin` happens to be a system interpreter, which path-equality alone would miss because the venv's `bin/python3` is a symlink to the host). Both `eval_proc` (inline `<| … |>`) and `py_func` paths are exercised.
+
 Parallel item tests: `test/validation/items/parallel/test.tum`
 
 ## Dependencies

build_all.sh

@@ -8,6 +8,9 @@
 # release_note.txt is copied to dist/ up front (with a warning if it has no
 # entry for the current version).
 #
+# By default, a step is skipped if its artifact already exists in dist/.
+# Pass --clean to remove existing dist/ artifacts and rebuild everything.
+#
 # All artifacts are collected (copied) under <repo>/dist/. Original outputs in
 # src/dist/, package/*/dist/, doc/manual/ are left in place. Wheel and AppImage
 # keep their original names (which already contain the version); manual,
@@ -15,17 +18,35 @@
 #
 # Re-uses scripts/build_env.sh and scripts/set_env.sh — the same pair invoked
 # by run.sh — so the venv at test/tmp/.venv stays the single source of Python
-# dependencies. `build` and `pyinstaller` are installed into that venv on
-# demand if not already there. Flatpak and AppImage build in their own
-# container/sandbox; their build.sh scripts have their own toolchain checks.
+# dependencies. `build`, `pyinstaller`, `sphinx` and `linuxdoc` are installed
+# into that venv on demand if not already there. Flatpak and AppImage build in
+# their own container/sandbox; their build.sh scripts have their own toolchain
+# checks.
 
 set -e
 
+CLEAN=0
+for arg in "$@"; do
+    case "$arg" in
+        --clean|-c) CLEAN=1 ;;
+        *) echo "Unknown option: $arg" >&2; exit 1 ;;
+    esac
+done
+
 SCRIPT_DIR=$(realpath "$(dirname "$0")")
 VERSION=$(cat "$SCRIPT_DIR/src/VERSION")
 DIST_DIR="$SCRIPT_DIR/dist"
 mkdir -p "$DIST_DIR"
 
+if [ "$CLEAN" -eq 1 ]; then
+    echo "-- clean: removing existing dist artifacts for version $VERSION"
+    rm -f "$DIST_DIR/testium-manual-${VERSION}.pdf"
+    rm -f "$DIST_DIR"/testium-${VERSION}-*.whl
+    rm -f "$DIST_DIR/testium-${VERSION}"
+    rm -f "$DIST_DIR/testium-${VERSION}.flatpak"
+    rm -f "$DIST_DIR"/Testium-${VERSION}-*.AppImage
+fi
+
 # Release note: copy it to dist/ and warn (but don't fail) if it has no entry
 # for the current version.
 RELEASE_NOTE_SRC="$SCRIPT_DIR/release_note.txt"
@@ -42,9 +63,6 @@ export REQ_PATH="$SCRIPT_DIR/src/requirements.txt"
 bash "$SCRIPT_DIR/scripts/build_env.sh"
 source "$SCRIPT_DIR/scripts/set_env.sh"
 
-# Ensure wheel/PyInstaller toolchains are present in the venv.
-python -m pip install --quiet --upgrade build pyinstaller
-
 step() {
     echo
     echo "================================================================"
@@ -52,51 +70,90 @@ step() {
     echo "================================================================"
 }
 
+skip() { echo "  (already built — skipping)"; }
+
 # 1. Manual PDF
-step "1/5  Manual PDF (version $VERSION)"
-bash "$SCRIPT_DIR/doc/manual/sphinx/build_doc.sh"
-MANUAL_SRC="$SCRIPT_DIR/doc/manual/testium_manual.pdf"
 MANUAL="$DIST_DIR/testium-manual-${VERSION}.pdf"
-cp -f "$MANUAL_SRC" "$MANUAL"
+step "1/5  Manual PDF (version $VERSION)"
+if [ ! -f "$MANUAL" ]; then
+    python -m pip install --quiet --upgrade sphinx linuxdoc
+    bash "$SCRIPT_DIR/doc/manual/sphinx/build_doc.sh"
+    cp -f "$SCRIPT_DIR/doc/manual/testium_manual.pdf" "$MANUAL"
+else
+    skip
+fi
 
 # 2. Wheel — PEP 427 name kept (already contains version)
 step "2/5  Wheel (version $VERSION)"
-(
-    cd "$SCRIPT_DIR/src"
-    rm -rf dist build *.egg-info
-    python -m build --wheel
-)
-WHEEL_SRC=$(ls -1t "$SCRIPT_DIR/src/dist"/*.whl | head -1)
-WHEEL="$DIST_DIR/$(basename "$WHEEL_SRC")"
-cp -f "$WHEEL_SRC" "$WHEEL"
+WHEEL=$(ls -1t "$DIST_DIR"/testium-${VERSION}-*.whl 2>/dev/null | head -1)
+if [ -z "$WHEEL" ]; then
+    python -m pip install --quiet --upgrade build
+    (
+        cd "$SCRIPT_DIR/src"
+        rm -rf dist build *.egg-info
+        python -m build --wheel
+    )
+    WHEEL_SRC=$(ls -1t "$SCRIPT_DIR/src/dist"/*.whl | head -1)
+    WHEEL="$DIST_DIR/$(basename "$WHEEL_SRC")"
+    cp -f "$WHEEL_SRC" "$WHEEL"
+else
+    skip
+fi
 
 # 3. PyInstaller binary
-step "3/5  PyInstaller binary (version $VERSION)"
-bash "$SCRIPT_DIR/package/pyinstaller/build.sh"
-PYI_SRC="$SCRIPT_DIR/package/pyinstaller/dist/testium"
 PYI_BIN="$DIST_DIR/testium-${VERSION}"
-cp -f "$PYI_SRC" "$PYI_BIN"
+step "3/5  PyInstaller binary (version $VERSION)"
+if [ ! -f "$PYI_BIN" ]; then
+    python -m pip install --quiet --upgrade pyinstaller
+    bash "$SCRIPT_DIR/package/pyinstaller/build.sh"
+    cp -f "$SCRIPT_DIR/package/pyinstaller/dist/testium" "$PYI_BIN"
+else
+    skip
+fi
 
 # 4. Flatpak bundle
-step "4/5  Flatpak bundle (version $VERSION)"
-(
-    cd "$SCRIPT_DIR/package/flatpak"
-    bash build.sh
-)
-FLATPAK_SRC="$SCRIPT_DIR/package/flatpak/testium.flatpak"
 FLATPAK_BUNDLE="$DIST_DIR/testium-${VERSION}.flatpak"
-cp -f "$FLATPAK_SRC" "$FLATPAK_BUNDLE"
+step "4/5  Flatpak bundle (version $VERSION)"
+if [ ! -f "$FLATPAK_BUNDLE" ]; then
+    FLATPAK_DEPS=(
+        "org.kde.Platform//6.10"
+        "org.kde.Sdk//6.10"
+        "io.qt.PySide.BaseApp//6.10"
+    )
+    if ! flatpak remotes --user | grep -q "^flathub"; then
+        echo "  Adding Flathub remote"
+        flatpak remote-add --user --if-not-exists flathub https://dl.flathub.org/repo/flathub.flatpakrepo
+    fi
+    for dep in "${FLATPAK_DEPS[@]}"; do
+        if ! flatpak info --user "$dep" &>/dev/null && ! flatpak info --system "$dep" &>/dev/null; then
+            echo "  Installing Flatpak dependency: $dep"
+            flatpak install --user --noninteractive flathub "$dep"
+        fi
+    done
+    (
+        cd "$SCRIPT_DIR/package/flatpak"
+        bash build.sh
+    )
+    cp -f "$SCRIPT_DIR/package/flatpak/testium.flatpak" "$FLATPAK_BUNDLE"
+else
+    skip
+fi
 
 # 5. AppImage
 step "5/5  AppImage (version $VERSION)"
-(
-    cd "$SCRIPT_DIR/package/appimage"
-    bash build.sh
-)
-APPIMAGE_SRC=$(ls -1t "$SCRIPT_DIR/package/appimage"/*.AppImage 2>/dev/null | head -1)
-APPIMAGE="$DIST_DIR/$(basename "$APPIMAGE_SRC")"
-cp -f "$APPIMAGE_SRC" "$APPIMAGE"
-chmod +x "$APPIMAGE"
+APPIMAGE=$(ls -1t "$DIST_DIR"/Testium-${VERSION}-*.AppImage 2>/dev/null | head -1)
+if [ -z "$APPIMAGE" ]; then
+    (
+        cd "$SCRIPT_DIR/package/appimage"
+        bash build.sh
+    )
+    APPIMAGE_SRC=$(ls -1t "$SCRIPT_DIR/package/appimage"/*.AppImage 2>/dev/null | head -1)
+    APPIMAGE="$DIST_DIR/$(basename "$APPIMAGE_SRC")"
+    cp -f "$APPIMAGE_SRC" "$APPIMAGE"
+    chmod +x "$APPIMAGE"
+else
+    skip
+fi
 
 step "All packages built"
 printf "  manual       : %s\n" "$MANUAL"

doc/examples/example_simple.tum

@@ -20,6 +20,22 @@ main:
           param:
               - 123
 
+      - py_func:
+          name: python long wait
+          doc: The purpose of this step is to try the tasks "stop" interruption
+          file: utils.py
+          func_name: long_wait
+          param:
+              - 10
+
+      - lua_func:
+          name: lua long wait
+          doc: The purpose of this step is to try the tasks "stop" interruption
+          file: lua_func.lua
+          func_name: long_wait
+          param:
+              - 10
+
       - sleep:
           name: sleep item
           dialog: true

doc/examples/lua_func.lua

@@ -1,4 +1,5 @@
 tm = require("tm")
+socket = require("socket")
 
 local module = {}
 
@@ -7,4 +8,8 @@ function module.func_to_be_executed(param)
     return param
 end
 
+function module.long_wait(sec)
+    socket.sleep(sec)
+end
+
 return module

doc/examples/param.yaml

@@ -17,18 +17,3 @@ plot_log_path: /tmp/testium_plot/$(testrun_date)/$(testrun_time)/
 python_path_Windows: C:\Users\François\Applications\Python313\python.exe
 python_path_Linux: $(home)/tmp/tum_venv/bin/python3
 
-# lua_bin_Windows: C:\Lua\5.1
-# lua_bin_Linux: /usr/bin/lua
-
-LUA_PATH_Linux: /usr/share/lua/5.4/?.lua;/usr/local/share/lua/5.4/?.lua;/usr/local/share/lua/5.4/?/init.lua;/usr/share/lua/5.4/?/init.lua;/usr/local/lib/lua/5.4/?.lua;/usr/local/lib/lua/5.4/?/init.lua;/usr/lib/lua/5.4/?.lua;/usr/lib/lua/5.4/?/init.lua;./?.lua;./?/init.lua;/home/francois/.luarocks/share/lua/5.4/?.lua;/home/francois/.luarocks/share/lua/5.4/?/init.lua
-LUA_CPATH_Linux: /usr/local/lib/lua/5.4/?.so;/usr/lib/lua/5.4/?.so;/usr/local/lib/lua/5.4/loadall.so;/usr/lib/lua/5.4/loadall.so;./?.so;/home/francois/.luarocks/lib/lua/5.4/?.so
-PATH_Linux:
-
-LUA_PATH_Windows: ;.\?.lua;C:\Lua\5.1\lua\?.lua;C:\Lua\5.1\lua\?\init.lua;C:\Lua\5.1\?.lua;C:\Lua\5.1\?\init.lua;C:\Lua\5.1\lua\?.luac
-LUA_CPATH_Windows: .\?.dll;C:\Lua\5.1\?.dll;C:\Lua\5.1\loadall.dll;C:\Lua\5.1\clibs\?.dll;C:\Lua\5.1\clibs\loadall.dll;.\?51.dll;C:\Lua\5.1\?51.dll;C:\Lua\5.1\clibs\?51.dll
-PATH_Windows: ""
-
-lua_env:
-  PATH: $(PATH_$(os))
-  LUA_PATH: $(LUA_PATH_$(os))
-  LUA_CPATH: $(LUA_CPATH_$(os))

doc/examples/utils.py

@@ -1,3 +1,5 @@
+from time import sleep
+
 def dummy_exit(useless1, useless2):
     return True
 
@@ -10,4 +12,7 @@ def funcToBeExecuted (bla):
 
 def funcToBeExecuted2 (bla):
     print(bla)
-    return blo
+    return blo
+
+def long_wait (sec):
+    sleep(sec)

package/flatpak/org.testium.Testium.yaml

@@ -16,6 +16,11 @@ finish-args:
   - --filesystem=home
   - --filesystem=/tmp
   - --filesystem=host-os
+  # Allow flatpak-spawn --host to launch host binaries (Python, Lua, git…)
+  # outside the sandbox. Required because the sandbox glibc/ABI is
+  # incompatible with arbitrary host shared libraries — we route py_func and
+  # lua_func through the host instead.
+  - --talk-name=org.freedesktop.Flatpak
 
 build-options:
   build-args:

release_note.txt

@@ -1,3 +1,30 @@
+version 0.1.3
+==============
+- Stop interrupts engaged blocking steps (console, py_func, lua_func,
+  json_rpc, sleep) within ~200 ms instead of waiting for the step
+  to finish.
+- GUI Start / Stop / Pause flow simplified.
+- lua_func: a function returning nil is no longer reported as a failure.
+- ``-d python_bin=...`` and the GUI ``python_bin`` preference now reach
+  the eval subprocess (used to be silently ignored). ``param.yaml`` can
+  also override ``python_bin`` for py_func / cycle / post_exec.
+- Validation suite: ``test/validation/run.sh`` (and ``run.bat``)
+  runs the suite inside a dedicated venv in the system temp dir.
+- build_all.sh: ``release_note.txt`` and the user manual copied into
+  ``dist/``; warning if the file has no entry for the version being built.
+- Flatpak: every GUI file/directory dialog (open test, save report, log
+  path, default report/log dirs, python/lua interpreter pickers) now
+  bypasses the XDG document portal — the v0.1.2 fix was only on the
+  "open test" dialog.
+- Flatpak: py_func / lua_func / run sub-instance now execute on the host
+  via flatpak-spawn, lifting the previous glibc/ABI incompatibility that
+  prevented user-configured host Python or Lua interpreters from being
+  reached from the sandbox.
+- Validation suite: single entry point with ``--mode source|wheel|
+  pyinstaller|flatpak|appimage`` to validate any packaging channel
+  against the same item set; reports are stamped per mode.
+- GUI: the "Run tum" test item now uses the testium logo.
+
 version 0.1.2
 ==============
 - Flatpak: opening a test from the GUI now correctly finds its companion

scripts/build_env.sh

@@ -20,6 +20,12 @@ if [ "$?" -ne 0 ]; then
     echo "venv must be installed on the host distribution."
     exit -1
 fi
+# Check if venv is installed
+python3 -c "import ensurepip"
+if [ "$?" -ne 0 ]; then
+    echo "ensurepip must be installed on the host distribution."
+    exit -1
+fi
 
 # Install the virtual environment if needed
 if [ ! -d "$PY_VENV_DIR" ]; then

src/VERSION

@@ -1 +1 @@
-0.1.2
+0.1.3

src/testium/api/console.py

@@ -11,6 +11,7 @@ import threading
 from telnetlib3 import Telnet, DO, WILL, WONT, TTYPE, IAC, SB, SE, theNULL
 
 TIMEOUT_NULL = 0.000001
+STOP_POLL_INTERVAL = 0.2
 
 
 class BytesStore(object):
@@ -123,12 +124,14 @@ A {classname}.close() is missing somewhere in your code !'.format(classname=type
         #    c = ''
         return c
 
-    def read_until(self, match, timeout=None, return_data=False, mute=False):
+    def read_until(self, match, timeout=None, return_data=False, mute=False, should_stop=None):
         """
         read until the string 'match is found
             If timeout is not set (None), this function runs indefinitely
             If timeout is set to zero, this function returns immediately
             If mute is set to True the characters read from the console will not be displayed
+            If should_stop is a callable, it is polled between reads (every STOP_POLL_INTERVAL
+            at most) and the loop exits early — like a timeout — when it returns True.
 
             If function fails (because of a timeout) it will return a 'status' integer set to -1
             otherwise it will return 0.
@@ -139,13 +142,6 @@ A {classname}.close() is missing somewhere in your code !'.format(classname=type
         status = -1
         if not match:
             raise ValueError('match parameter can not be empty')
-        # replace all '\r' by '\n' as any '\r' read will undergo the same replacement
-        # match = match.replace('\r\n', '\n')
-        # match = match.replace('\r', '')
-
-        # update the console timeout in conformity with what is required.
-
-        self.set_read_timeout(timeout)
 
         if timeout is None:
             timeout = 1000000
@@ -159,6 +155,7 @@ A {classname}.close() is missing somewhere in your code !'.format(classname=type
         # buffer is empty
         # Otherwise we are waiting for the timeout to rise
         if timeout < TIMEOUT_NULL:
+            self.set_read_timeout(0)
             data = self.readchar(0)
 
             while (status < 0) and ((data is not None) and (data != b'')):
@@ -191,39 +188,45 @@ A {classname}.close() is missing somewhere in your code !'.format(classname=type
 
         # Timeout different than zero
         else:
+            # Poll in short chunks so a stop request is honored within
+            # STOP_POLL_INTERVAL, regardless of the per-protocol blocking
+            # behavior of readchar().
+            self.set_read_timeout(STOP_POLL_INTERVAL)
 
             time_is_out = threading.Event()
             timer = threading.Timer(timeout, lambda: time_is_out.set())
             timer.start()
 
-            # We are waiting for the timeout to rise
+            try:
+                while (status < 0) and (not time_is_out.is_set()):
+                    if should_stop is not None and should_stop():
+                        break
 
-            while (status < 0) and (not time_is_out.isSet()):
-
-                data = self.readchar(timeout)
-                if data is not None:
-                    data = self._compute_char(data)
-                    if data != '':
-                        if not mute:
-                            self.string_buffer += data
-                        read_data += data
-
-                        search_deque.append(data)
-                        if search_deque == match_deque:
-                            timer.cancel()
-                            status = 0
-                            if (not mute) and (data != '\n'):
-                                self.string_buffer += '\n'
-
-                        if data == '\n' or (status >= 0):
-                            # the datas are written line by line for display optimisation in GUI mode
+                    data = self.readchar(STOP_POLL_INTERVAL)
+                    if data is not None:
+                        data = self._compute_char(data)
+                        if data != '':
                             if not mute:
-                                self.string_buffer = self.string_buffer.replace('\r\n', '\n')
-                                self.string_buffer = self.string_buffer.replace('\r', '')
-                                self.stream.write(self.string_buffer)
+                                self.string_buffer += data
+                            read_data += data
 
-                            date_str = str(datetime.now()).split('.')[0].split(' ')[1]
-                            self.string_buffer = '[{} {}]'.format(date_str, self.name)
+                            search_deque.append(data)
+                            if search_deque == match_deque:
+                                status = 0
+                                if (not mute) and (data != '\n'):
+                                    self.string_buffer += '\n'
+
+                            if data == '\n' or (status >= 0):
+                                # the datas are written line by line for display optimisation in GUI mode
+                                if not mute:
+                                    self.string_buffer = self.string_buffer.replace('\r\n', '\n')
+                                    self.string_buffer = self.string_buffer.replace('\r', '')
+                                    self.stream.write(self.string_buffer)
+
+                                date_str = str(datetime.now()).split('.')[0].split(' ')[1]
+                                self.string_buffer = '[{} {}]'.format(date_str, self.name)
+            finally:
+                timer.cancel()
 
         if return_data:
             return status, read_data

src/testium/interpreter/process.py

@@ -16,6 +16,7 @@ from interpreter.utils.test_init import (
     env_init,
     prepare_global,
     update_global,
+    apply_overrides,
     set_standard_gd_keys,
     test_run_init,
     test_run_header,
@@ -210,6 +211,19 @@ class TestProcess(Process):
 
                 env_init()
 
+                # Apply GUI defaults and CLI defines to the global dict
+                # *before* eval_proc starts: bins.python_bin() reads
+                # ``python_bin`` from gd on its very first call (during
+                # eval_process_init) and caches the result. Without this,
+                # ``-d python_bin=...`` and the GUI ``python_bin`` preference
+                # would only take effect for items spawned *after* the cache
+                # was already populated with the auto-discovered interpreter,
+                # i.e. they would silently be ignored for eval_proc itself.
+                # _load_initial_params re-applies the same overrides after
+                # ``prepare_global()`` clears gd, so the gd value stays in
+                # sync with the cached path.
+                apply_overrides(self.__defs, self.__gui_defaults)
+
                 # Creation of the python evaluation process for loading of the complete test
                 eval_proc = eval_process_init(api_request, 10, test_dir)
                 eval_proc.start()

src/testium/interpreter/test_items/test_item.py

@@ -20,52 +20,64 @@ class TestItem:
 def test_run(f):
     @wraps(f)
     def wrapper(self):
-        if not self.skipped:
-            if self.enabled:
-                self.run_test_init()
-                # Conditional execution
-                raw_condition = self._prms.getParam(
-                    "condition", default=None, processed=False
-                )
-                if raw_condition is None:
-                    condition = True
-                else:
-                    c = self._prms.expanse(raw_condition)
-                    if isinstance(c, bool):
-                        condition = c
-                    else:
-                        condition = False
-                        c = False
-
-                    if raw_condition == c:
-                        msg = f'"{c}"'
-                    else:
-                        msg = f'"{raw_condition}" --> "{c}"'
-
-                # Do we have to skip the test because of a true condition ?
-                if condition:
-                    if not raw_condition is None:
-                        msg = "condition met: " + msg
-                        self.result.reported = {"input_condition": msg}
-                        print(msg)
-                    # Test preparation
-                    self.run_before_test()
-                    # Test execution
-                    f(self)
-                else:
-                    msg = "condition not met: " + msg
-                    self.result.set(TestValue.NORUN, msg)
-                    self.result.reported = {"input_condition": msg}
-                self.run_test_end()
-            else:
-                self.result.set(TestValue.NORUN, "test disabled")
-                print("Test is disabled.")
-        else:
+        if self.skipped:
             self.result.set(TestValue.NORUN, "test skipped")
             print("Test is skipped.")
+            return self.result
+        
+        if not self.enabled:
+            self.result.set(TestValue.NORUN, "test disabled")
+            print("Test is disabled.")
+            return self.result
+
+        self.run_test_init()
+
+        while self._is_paused:
+            sleep(0.2)
+            if self.isStopped() :
+                self.result.set(TestValue.NORUN, "test stopped")
+                print("Test is Stopped.")
+                self._is_stopped = False    # Restore state for next run
+                return self.result
+
+        # Conditional execution
+        raw_condition = self._prms.getParam(
+            "condition", default=None, processed=False
+        )
+        if raw_condition is None:
+            condition = True
+        else:
+            c = self._prms.expanse(raw_condition)
+            if isinstance(c, bool):
+                condition = c
+            else:
+                condition = False
+                c = False
+
+            if raw_condition == c:
+                msg = f'"{c}"'
+            else:
+                msg = f'"{raw_condition}" --> "{c}"'
+
+        # Do we have to skip the test because of a true condition ?
+        if condition:
+            if not raw_condition is None:
+                msg = "condition met: " + msg
+                self.result.reported = {"input_condition": msg}
+                print(msg)
+            # Test preparation
+            self.run_before_test()
+            # Test execution
+            f(self)
+        else:
+            msg = "condition not met: " + msg
+            self.result.set(TestValue.NORUN, msg)
+            self.result.reported = {"input_condition": msg}
+        self.run_test_end()
 
         return self.result
 
+
     return wrapper
 
 
@@ -255,8 +267,6 @@ class TestItem:
         self._sendStatusStarted()
         if self._is_breakpoint:
             self._is_paused = True
-            while self._is_paused:
-                sleep(0.2)
 
         if self.is_container:
             self.report.incLevel()
@@ -274,9 +284,6 @@ class TestItem:
         if self.is_container:
             self.report.decLevel()
 
-        while self._is_paused:
-            sleep(0.2)
-
         # Post evaluation of the test result
         self.process_result()
         # expected_result treatment
@@ -310,6 +317,7 @@ class TestItem:
             self.process_report(self._reported)
         self.report.addTest(self, self.result, rk)
         self._sendStatusFinished()
+        
 
     def process_result(self):
         if self._post_eval is None:

src/testium/interpreter/test_items/test_item_console.py

@@ -307,11 +307,17 @@ class TestItemConsoleReadUntil(TestItemConsoleAction):
 
         try:
             status, data = cons.read_until(
-                ru, timeout=read_timeout, return_data=True, mute=mute
+                ru, timeout=read_timeout, return_data=True, mute=mute,
+                should_stop=self.isStopped,
             )
             if status == 0:
                 self.result.set(TestValue.SUCCESS)
                 self.result.value = data
+            elif self.isStopped():
+                self.result.set(
+                    result=TestValue.FAILURE,
+                    message="Console read aborted on stop request",
+                )
             else:
                 self.result.set(result=TestValue.FAILURE, message="No matching text")
             if mute:

src/testium/interpreter/test_items/test_item_json_rpc/__init__.py

@@ -105,6 +105,7 @@ class TestItemJSRPCActionQuery(TestItemAction):
             jrpc_id = randint(1, (2**32) - 1)
         send_only = self._prms.expanse(self._send_only)
         timeout = self._prms.expanse(self._timeout)
+        self.token.set_should_stop(self.isStopped)
         try:
             success, result = self.token.query(
                 meth, obj, jrpc_id, send_only, timeout=timeout
@@ -146,6 +147,7 @@ class TestItemJSRPCActionReceive(TestItemAction):
     def execute(self):
         timeout = self._prms.expanse(self._timeout)
         jrpc_id = self._prms.expanse(self._jrpc_id)
+        self.token.set_should_stop(self.isStopped)
 
         try:
             success, result = self.token.receive(jrpc_id, timeout)

src/testium/interpreter/test_items/test_item_json_rpc/jsonrpc_adapters.py

@@ -2,10 +2,11 @@ import json
 import socket
 import re
 import struct
+import time
 
 from runtime.tum_except import ETUMRuntimeError
 import api.testium as tm
-from api.console import Console
+from api.console import Console, STOP_POLL_INTERVAL
 
 
 def is_ip_address(address):
@@ -45,9 +46,16 @@ class JrpcAdapter:
         self._jrpc_version = version
         self._mute = mute
         self._timeout = timeout
+        # Optional callable polled by _receive() implementations to abort
+        # waits early when the test is being stopped. Set by the test item
+        # action before each query/receive call.
+        self._should_stop = None
         if not (version == "1.0" or version == "2.0"):
             raise ETUMRuntimeError("Invalid JSONRPC version passed.")
 
+    def set_should_stop(self, cb):
+        self._should_stop = cb
+
     @property
     def timeout(self):
         return self._timeout
@@ -249,32 +257,38 @@ class JrpcUdpAdapter(JrpcAdapter):
             print(f"  | sent to @{self._server}:{self._snd_port}")
 
     def _receive(self, timeout: float) -> str:
+        # Poll in short chunks so a stop request is honored within
+        # STOP_POLL_INTERVAL.
+        self.sock.settimeout(STOP_POLL_INTERVAL)
+        deadline = time.monotonic() + float(timeout)
+        data = None
+        addr = None
+        while True:
+            if self._should_stop is not None and self._should_stop():
+                raise ETUMRuntimeError("JSONRPC udp receive aborted on stop request.")
+            try:
+                data, addr = self.sock.recvfrom(self._bufsize)
+                break
+            except socket.timeout:
+                if time.monotonic() >= deadline:
+                    raise ETUMRuntimeError(
+                        "JSONRPC udp answer took too long. Try to increase the timeout."
+                    )
 
-        # configures the reception timeout
-        self.sock.settimeout(timeout)
-
-        # Receives the answer from the server
-        try:
-            data, addr = self.sock.recvfrom(self._bufsize)
-
-            # In case of buffer overload we chose to complain
-            if len(data) >= self._bufsize:
-                raise ETUMRuntimeError(
-                    "JSONRPC udp answer size overflow. Try to increase the bufsize"
-                )
-
-            # Converts binary to string
-            res = data.decode()
-
-            # Don't log if mute
-            if not self._mute:
-                print(f"  | UDP answer: '{res}'")
-                print(f"  | received from @{addr[0]}:{addr[1]}")
-
-        except socket.timeout:
+        # In case of buffer overload we chose to complain
+        if len(data) >= self._bufsize:
             raise ETUMRuntimeError(
-                "JSONRPC udp answer took too long. Try to increase the timeout."
+                "JSONRPC udp answer size overflow. Try to increase the bufsize"
             )
+
+        # Converts binary to string
+        res = data.decode()
+
+        # Don't log if mute
+        if not self._mute:
+            print(f"  | UDP answer: '{res}'")
+            print(f"  | received from @{addr[0]}:{addr[1]}")
+
         return res
 
     def _build_query(self, method: str, obj, jrpc_id: int):
@@ -339,11 +353,16 @@ class JrpcConsoleAdapter(JrpcAdapter):
 
     def _receive(self, timeout: float) -> str:
         status, data = self._cons.read_until(
-            self._endswith, timeout, return_data=True, mute=self._mute
+            self._endswith, timeout, return_data=True, mute=self._mute,
+            should_stop=self._should_stop,
         )
 
         # if we did not receive anything, we complain
         if not status == 0:
+            if self._should_stop is not None and self._should_stop():
+                raise ETUMRuntimeError(
+                    f"JSONRPC console receive aborted on stop request."
+                )
             raise ETUMRuntimeError(
                 f"The '{self._cons.name}' console did not answer in the requested time."
             )

src/testium/interpreter/test_items/test_item_lua_func.py

@@ -45,6 +45,18 @@ class TestItemLuaFunc(TestItem):
             tm.setgd(_LUA_FUNC_CONTEXTS_KEY, contexts)
         return contexts[ctx_id], True
 
+    def stop(self):
+        super().stop()
+        # Tear down the worker so any in-flight func_call returns promptly.
+        # join() clears _rpc/_process so a subsequent item reusing the same
+        # context_id can restart the engine cleanly.
+        try:
+            engine, _ = self._get_engine()
+            engine.stop()
+            engine.join()
+        except Exception:
+            pass
+
     @test_run
     def execute(self):
         self.result.set(
@@ -96,9 +108,15 @@ Is the lua environnment well defined in the "LUA_PATH" and "LUA_CPATH" variables
 
             return
 
+        except ConnectionAbortedError:
+            self.result.set(TestValue.FAILURE, "lua_func aborted on stop request")
+            print("lua_func aborted on stop request.")
         except:
             traceback.print_exception(*sys.exc_info())
-            self.result.set(
-                TestValue.FAILURE,
-                'Unrecoverable "lua_func" item error from {}'.format(self.func_name),
-            )
+            if self.isStopped():
+                self.result.set(TestValue.FAILURE, "lua_func aborted on stop request")
+            else:
+                self.result.set(
+                    TestValue.FAILURE,
+                    'Unrecoverable "lua_func" item error from {}'.format(self.func_name),
+                )

src/testium/interpreter/test_items/test_item_py_func.py

@@ -45,6 +45,18 @@ class TestItemPyFunc(TestItem):
             tm.setgd(_PY_FUNC_CONTEXTS_KEY, contexts)
         return contexts[ctx_id], True
 
+    def stop(self):
+        super().stop()
+        # Tear down the worker so any in-flight func_call returns promptly.
+        # join() clears _rpc/_process so a subsequent item reusing the same
+        # context_id can restart the engine cleanly.
+        try:
+            engine, _ = self._get_engine()
+            engine.stop()
+            engine.join()
+        except Exception:
+            pass
+
     @test_run
     def execute(self):
         self.result.set(
@@ -94,9 +106,15 @@ python_bin = {tm.gd("python_bin", "no python path defined")}"""
 
             return
 
+        except ConnectionAbortedError:
+            self.result.set(TestValue.FAILURE, "py_func aborted on stop request")
+            print("py_func aborted on stop request.")
         except:
             traceback.print_exception(*sys.exc_info())
-            self.result.set(
-                TestValue.FAILURE,
-                'Unrecoverable "py_func" item error from {}'.format(self.func_name),
-            )
+            if self.isStopped():
+                self.result.set(TestValue.FAILURE, "py_func aborted on stop request")
+            else:
+                self.result.set(
+                    TestValue.FAILURE,
+                    'Unrecoverable "py_func" item error from {}'.format(self.func_name),
+                )

src/testium/interpreter/test_items/test_item_run.py

@@ -24,9 +24,15 @@ def _testium_launch_cmd():
     appimage = os.environ.get("APPIMAGE")
     if appimage:
         return [appimage]
-    # Flatpak: re-launch via the Flatpak app id.
+    # Flatpak: re-launch via the Flatpak app id, but on the host side —
+    # the `flatpak` CLI cannot run inside our sandbox (no D-Bus access to the
+    # host Flatpak service, and the host binary would need host libs that are
+    # ABI-incompatible with the sandbox runtime). flatpak-spawn proxies the
+    # call to the host via org.freedesktop.Flatpak (allowed by --talk-name in
+    # the manifest).
     if os.path.isfile("/.flatpak-info"):
-        return ["flatpak", "run", "org.testium.Testium"]
+        return ["flatpak-spawn", "--host",
+                "flatpak", "run", "org.testium.Testium"]
     # PyInstaller frozen exe: sys.executable is the binary itself.
     if getattr(sys, "frozen", False):
         return [sys.executable]

src/testium/interpreter/test_items/test_item_sleep.py

@@ -80,4 +80,7 @@ class TestItemSleep(TestItem):
             end_time = _time.time() + float(timeout)
             while _time.time() < end_time and not self._is_stopped:
                 sleep(min(0.05, end_time - _time.time()))
-            self.result.set(TestValue.SUCCESS, 'Sleep %s sec' % (str(timeout)))
+            if self._is_stopped:
+                self.result.set(TestValue.FAILURE, 'Sleep aborted on stop request')
+            else:
+                self.result.set(TestValue.SUCCESS, 'Sleep %s sec' % (str(timeout)))

src/testium/interpreter/utils/bins.py

@@ -17,8 +17,11 @@ Public API
 ``reset()``             : clear the cache (mostly useful for tests)
 """
 
+import atexit
 import os
+import shutil
 import subprocess
+import tempfile
 
 import api.testium as tm
 from interpreter.utils.paths import sys_app_path_lin, sys_app_path_win
@@ -30,20 +33,6 @@ from runtime.tum_except import ETUMRuntimeError
 _PYTHON_CANDIDATES = ["python3", "python"]
 _LUA_CANDIDATES = ["lua", "lua5.5", "lua5.4", "lua5.3", "lua5.2", "lua5.1"]
 
-# When running inside a Flatpak, --filesystem=host-os mounts the host at
-# /run/host (read-only). Binaries and libraries from the host are not on the
-# sandbox PATH/LD_LIBRARY_PATH, so we probe and inject them explicitly.
-_FLATPAK_HOST_DIRS = [
-    "/run/host/usr/local/bin",
-    "/run/host/usr/bin",
-    "/run/host/bin",
-]
-_FLATPAK_HOST_LIB_DIRS = [
-    "/run/host/usr/lib",
-    "/run/host/usr/lib64",
-    "/run/host/usr/local/lib",
-]
-
 # Inside an AppImage, AppRun prepends $APPDIR/usr/bin to PATH and exports a
 # bundle-local PYTHONHOME / PYTHONPATH / LD_LIBRARY_PATH. We want py_func and
 # lua_func to run under the *host* interpreter (not the bundled one), so we
@@ -64,78 +53,162 @@ def _in_appimage():
     return "APPIMAGE" in os.environ
 
 
-def apply_host_lua_paths(env):
-    """Prepend host Lua module dirs to LUA_PATH / LUA_CPATH (Flatpak only).
-
-    Must be called after user-defined lua_env overrides are applied, so host
-    paths are always first regardless of user config. User-defined paths remain
-    in the variable but after the host ones.
-    """
-    if not _in_flatpak():
-        return
-    _LUA_VERSIONS = ["5.5", "5.4", "5.3", "5.2", "5.1"]
-    _HOST = "/run/host/usr"
-    cpath_dirs, lpath_dirs = [], []
-    for v in _LUA_VERSIONS:
-        for base in [f"{_HOST}/lib/lua/{v}",
-                     f"{_HOST}/lib64/lua/{v}",
-                     f"{_HOST}/lib/x86_64-linux-gnu/lua/{v}"]:
-            cpath_dirs.append(f"{base}/?.so")
-        lpath_dirs.append(f"{_HOST}/share/lua/{v}/?.lua")
-        lpath_dirs.append(f"{_HOST}/share/lua/{v}/?/init.lua")
-    sep = ";"
-    host_cpath = sep.join(cpath_dirs)
-    host_lpath = sep.join(lpath_dirs)
-    # ;; keeps Lua's compiled-in defaults at the end as last resort
-    env["LUA_CPATH"] = host_cpath + sep + env.get("LUA_CPATH", ";;")
-    env["LUA_PATH"]  = host_lpath + sep + env.get("LUA_PATH",  ";;")
-
-
 def apply_host_libs(env):
-    """Prepare *env* for launching a host binary from inside our bundle.
+    """Strip bundle-local entries from *env* so a host binary can run cleanly.
 
-    - Flatpak: prepend host library dirs to LD_LIBRARY_PATH so the dynamic
-      linker can find host .so files mounted under /run/host.
-    - AppImage: strip $APPDIR-prefixed entries from LD_LIBRARY_PATH and
-      PYTHONPATH and drop PYTHONHOME, so the host interpreter doesn't try
-      to load the bundled (incompatible) Python lib/site-packages.
-    - Otherwise: no-op.
+    Only meaningful for AppImage: removes $APPDIR-prefixed entries from
+    LD_LIBRARY_PATH / PYTHONPATH / PATH and drops PYTHONHOME, so the host
+    interpreter doesn't try to load the bundled (incompatible) Python
+    lib/site-packages. Flatpak is handled via flatpak-spawn --host instead
+    (see flatpak_host_spawn), so the sandbox env is irrelevant there.
     """
-    if _in_flatpak():
-        dirs = ":".join(d for d in _FLATPAK_HOST_LIB_DIRS if os.path.isdir(d))
-        if dirs:
-            existing = env.get("LD_LIBRARY_PATH", "")
-            env["LD_LIBRARY_PATH"] = dirs + (":" + existing if existing else "")
+    if not _in_appimage():
         return
-    if _in_appimage():
-        appdir = os.environ.get("APPDIR", "")
-        if appdir:
-            for var, sep in (("LD_LIBRARY_PATH", ":"),
-                             ("PYTHONPATH", os.pathsep),
-                             ("PATH", os.pathsep)):
-                cur = env.get(var, "")
-                if not cur:
-                    continue
-                cleaned = sep.join(
-                    p for p in cur.split(sep)
-                    if p and not p.startswith(appdir)
-                )
-                if cleaned:
-                    env[var] = cleaned
-                else:
-                    env.pop(var, None)
-        env.pop("PYTHONHOME", None)
+    appdir = os.environ.get("APPDIR", "")
+    if appdir:
+        for var, sep in (("LD_LIBRARY_PATH", ":"),
+                         ("PYTHONPATH", os.pathsep),
+                         ("PATH", os.pathsep)):
+            cur = env.get(var, "")
+            if not cur:
+                continue
+            cleaned = sep.join(
+                p for p in cur.split(sep)
+                if p and not p.startswith(appdir)
+            )
+            if cleaned:
+                env[var] = cleaned
+            else:
+                env.pop(var, None)
+    env.pop("PYTHONHOME", None)
+
+
+# ---------- Flatpak: spawn on host outside the sandbox -----------------------
+#
+# Inside a Flatpak the sandbox glibc is incompatible with host shared libraries,
+# so we can't run host Python/Lua under the sandbox runtime — `LD_LIBRARY_PATH`
+# tricks hit a `_dl_call_libc_early_init` assertion. The supported way out is
+# `flatpak-spawn --host`, which talks to the session-bus Flatpak D-Bus service
+# (org.freedesktop.Flatpak.Development) and asks it to spawn a process in the
+# host execution environment instead of inside our sandbox. The manifest must
+# grant `--talk-name=org.freedesktop.Flatpak` for the D-Bus call to be allowed.
+#
+# The host process can't see our /app/ contents (sandbox-only), so when we
+# spawn host Python/Lua to run `py_func` / `lua_func`, the cwd must be a
+# directory both sides can reach. /tmp is shared (--filesystem=/tmp), so we
+# stage the testium package there once per process and reuse it for every
+# spawn. In source mode (testium under $HOME) the host already sees the
+# original path, so we skip the copy.
+
+_staged_testium_path = None
+
+
+def _get_host_testium_path():
+    """Return a path to the testium package that the host can read.
+
+    - Source / wheel / PyInstaller install under $HOME → return testium_path()
+      as-is (host sees the same path via --filesystem=home).
+    - Flatpak bundle (testium under /app/) → stage a copy under /tmp on first
+      call and reuse it for the rest of the process.
+    """
+    global _staged_testium_path
+    if _staged_testium_path is not None:
+        return _staged_testium_path
+
+    # Imported lazily to avoid a circular import (paths.py -> api.testium).
+    from interpreter.utils.paths import testium_path
+    tp = testium_path()
+
+    if not tp.startswith("/app/"):
+        _staged_testium_path = tp
+        return tp
+
+    staged = tempfile.mkdtemp(prefix="testium_host_", dir="/tmp")
+    # copytree refuses to write into an existing dir unless dirs_exist_ok=True.
+    # mkdtemp creates the dir, so we copy *into* it.
+    for entry in os.listdir(tp):
+        src = os.path.join(tp, entry)
+        dst = os.path.join(staged, entry)
+        if os.path.isdir(src):
+            shutil.copytree(src, dst, symlinks=True)
+        else:
+            shutil.copy2(src, dst, follow_symlinks=False)
+    _staged_testium_path = staged
+    atexit.register(shutil.rmtree, staged, ignore_errors=True)
+    return staged
+
+
+_FORWARDED_ENV_KEYS = (
+    "HOME", "USER", "LOGNAME", "TMPDIR",
+    "XDG_RUNTIME_DIR", "XDG_DATA_HOME", "XDG_CONFIG_HOME", "XDG_CACHE_HOME",
+    "DBUS_SESSION_BUS_ADDRESS", "DISPLAY", "WAYLAND_DISPLAY",
+    "LANG", "LC_ALL",
+)
+
+
+def flatpak_host_spawn(interp_bin, cmd_args, host_cwd, extra_env=None):
+    """Build a flatpak-spawn --host command vector.
+
+    Args:
+        interp_bin: absolute path to the host interpreter (e.g. /usr/bin/python3).
+        cmd_args: list of arguments passed to the interpreter.
+        host_cwd: working directory on the host (must be reachable from host).
+        extra_env: optional {name: value} of env vars to set on the host side
+                   in addition to the default forwarded set. Values of ""
+                   unset the variable on the host.
+
+    Returns a list suitable for subprocess.Popen.
+    """
+    spawn = ["flatpak-spawn", "--host", f"--directory={host_cwd}"]
+    forwarded = {}
+    for key in _FORWARDED_ENV_KEYS:
+        val = os.environ.get(key)
+        if val:
+            forwarded[key] = val
+    if extra_env:
+        forwarded.update(extra_env)
+    for k, v in forwarded.items():
+        if v == "":
+            spawn.append(f"--unset-env={k}")
+        else:
+            spawn.append(f"--env={k}={v}")
+    spawn.append(interp_bin)
+    spawn.extend(cmd_args)
+    return spawn
+
+
+def _which_host_flatpak(name):
+    """Resolve a binary name (or absolute path) on the host via flatpak-spawn.
+
+    We can't probe /run/host/... because (a) only host-os is mounted there,
+    not arbitrary paths like /scratch, and (b) returning a /run/host path
+    would be useless — the host-side spawn sees a different filesystem and
+    needs the host-native path anyway.
+    """
+    if os.path.isabs(name):
+        cmd = flatpak_host_spawn("/bin/sh", ["-c", f'test -x "{name}"'],
+                                 host_cwd="/tmp")
+        try:
+            r = subprocess.run(cmd, capture_output=True, timeout=10)
+        except (FileNotFoundError, PermissionError, subprocess.TimeoutExpired):
+            return ""
+        return name if r.returncode == 0 else ""
+    cmd = flatpak_host_spawn("/bin/sh", ["-c", f'command -v "{name}"'],
+                             host_cwd="/tmp")
+    try:
+        r = subprocess.run(cmd, capture_output=True, text=True, timeout=10)
+    except (FileNotFoundError, PermissionError, subprocess.TimeoutExpired):
+        return ""
+    if r.returncode != 0:
+        return ""
+    return r.stdout.strip()
 
 
 def _which(name):
     if tm.OS() == "Windows":
         return sys_app_path_win(name)
     if _in_flatpak():
-        for d in _FLATPAK_HOST_DIRS:
-            p = os.path.join(d, name)
-            if os.path.isfile(p) and os.access(p, os.X_OK):
-                return p
-        return ""
+        return _which_host_flatpak(name)
     if _in_appimage():
         for d in _APPIMAGE_HOST_DIRS:
             p = os.path.join(d, name)
@@ -146,14 +219,33 @@ def _which(name):
 
 
 def _probe_env():
-    """Subprocess env for probing host binaries (adds host libs in Flatpak)."""
+    """Subprocess env for probing host binaries.
+
+    In AppImage we still need to scrub APPDIR-prefixed entries; in Flatpak we
+    delegate execution to the host via flatpak-spawn so the sandbox env doesn't
+    matter, but apply_host_libs is a no-op cost.
+    """
     env = os.environ.copy()
     apply_host_libs(env)
     return env
 
 
-def _python_version(path):
-    cmd = [path, "-c", "import sys; print(sys.version_info[:3])"]
+def _run_probe(cmd):
+    """Run a probe command, dispatching through flatpak-spawn --host in Flatpak.
+
+    Returns (stdout, stderr) as str, or None on failure.
+    """
+    if _in_flatpak():
+        spawn = flatpak_host_spawn(cmd[0], cmd[1:], host_cwd="/tmp")
+        try:
+            r = subprocess.run(
+                spawn, capture_output=True, text=True, timeout=10,
+            )
+        except (FileNotFoundError, PermissionError, subprocess.TimeoutExpired):
+            return None
+        if r.returncode != 0:
+            return None
+        return r.stdout, r.stderr
     try:
         r = subprocess.run(
             cmd, capture_output=True, text=True,
@@ -161,8 +253,15 @@ def _python_version(path):
         )
     except (FileNotFoundError, PermissionError, subprocess.TimeoutExpired):
         return None
+    return r.stdout, r.stderr
+
+
+def _python_version(path):
+    out = _run_probe([path, "-c", "import sys; print(sys.version_info[:3])"])
+    if out is None:
+        return None
     try:
-        return eval(r.stdout)
+        return eval(out[0])
     except Exception:
         return None
 
@@ -173,15 +272,11 @@ def _is_python3(path):
 
 
 def _lua_version(path):
-    try:
-        r = subprocess.run(
-            [path, "-v"], capture_output=True, text=True, timeout=10,
-            env=_probe_env(),
-        )
-    except (FileNotFoundError, PermissionError, subprocess.TimeoutExpired):
+    out = _run_probe([path, "-v"])
+    if out is None:
         return None
     # On Windows the version banner goes to stderr.
-    line = r.stdout or r.stderr
+    line = out[0] or out[1]
     try:
         major, minor, _patch = line.split(" ")[1].split(".")
         return (int(major), int(minor))
@@ -202,22 +297,33 @@ _SPECS = {
     "lua":    ("Lua 5.1+",  "lua_bin",    _LUA_CANDIDATES,    _is_lua51),
 }
 
+# Cached per (name, override) so that runtime changes to gd[gd_key] —
+# e.g. ``python_bin`` set from a YAML config file loaded *after*
+# eval_proc has already resolved its own interpreter — are picked up by
+# the next lookup instead of returning the stale, auto-discovered path.
+# Long-lived subprocesses (eval_proc) keep whatever they captured at
+# construction time, but every new PyProcessBase / FuncExecEngine spawned
+# afterwards sees the current override.
 _resolved = {}
 
 
 def _resolve(name):
-    if name in _resolved:
-        return _resolved[name]
-
     display, gd_key, candidates, validator = _SPECS[name]
     override = tm.gd(gd_key, "") or ""
 
+    cached = _resolved.get(name)
+    if cached is not None and cached[0] == override:
+        return cached[1]
+
     path = ""
     if override:
         # Absolute path: accept as-is (user knows exactly what they want).
         # Bare name: resolve via _which() so the override stays host-only in
         # Flatpak/AppImage instead of silently picking the bundled interpreter.
-        if os.path.isabs(override):
+        # In Flatpak we always defer to _which() so even absolute paths are
+        # checked from the host's perspective (the sandbox can't see e.g.
+        # /scratch/... paths that the user may have configured).
+        if os.path.isabs(override) and not _in_flatpak():
             resolved = override if (os.path.isfile(override)
                                     and os.access(override, os.X_OK)) else ""
         else:
@@ -239,7 +345,7 @@ def _resolve(name):
                 path = p
                 break
 
-    _resolved[name] = path
+    _resolved[name] = (override, path)
     return path
 
 

src/testium/interpreter/utils/lua_process.py

@@ -47,9 +47,16 @@ class LuaProcessBase:
         if self._process is not None:
             raise ETUMRuntimeError("The function subprocess has already been started.")
 
-        func_proc_path = os.path.realpath(
-            os.path.join(subproc_path(), "lua_func")
-        )
+        # In Flatpak the host can't see /app/lib/testium/lua_func, so use a
+        # staged copy under /tmp (shared between sandbox and host).
+        if bins._in_flatpak():
+            func_proc_path = os.path.join(
+                bins._get_host_testium_path(), "lua_func"
+            )
+        else:
+            func_proc_path = os.path.realpath(
+                os.path.join(subproc_path(), "lua_func")
+            )
 
         # POpen config
         CUST_ENV = {
@@ -71,7 +78,6 @@ class LuaProcessBase:
                     env[k] = e
                 else:
                     env[k] = e + ";" + env.get(k, "")
-        bins.apply_host_lua_paths(env)
 
         sock = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
         sock.bind(("localhost", 0))
@@ -79,8 +85,7 @@ class LuaProcessBase:
         sock.close()
 
         # POpen params
-        params = [
-            self._lbin,
+        cmd_args = [
             "main.lua",
             "--timeout",
             f"{self._timeout}",
@@ -91,14 +96,31 @@ class LuaProcessBase:
         ]
 
         if tm.debug_enabled() and tm.gd("debug_rpc", False):
-            params.append("--verbose")
+            cmd_args.append("--verbose")
+
+        if bins._in_flatpak():
+            # Run on the host outside the sandbox: avoids glibc ABI mismatches
+            # between the Flatpak runtime and host shared libraries.
+            host_env = {
+                k: env[k] for k in ("LUA_PATH", "LUA_CPATH", "PATH")
+                if k in env and env[k]
+            }
+            params = bins.flatpak_host_spawn(
+                self._lbin, cmd_args, host_cwd=func_proc_path,
+                extra_env=host_env,
+            )
+            popen_kwargs = {}
+        else:
+            params = [self._lbin, *cmd_args]
+            popen_kwargs = {"env": env, "cwd": func_proc_path}
 
         self._process = subprocess.Popen(
-            params, env=env, cwd=func_proc_path,
+            params,
             stdin=subprocess.DEVNULL,
             stdout=subprocess.PIPE,
             stderr=subprocess.PIPE,
             restore_signals=False,
+            **popen_kwargs,
         )
         # Route subprocess stdout/stderr (lua require failures, syntax
         # errors, anything written to fd 1/2 before the in-script
@@ -146,4 +168,12 @@ class LuaProcessBase:
         """
         if self._rpc is not None:
             self._rpc.stop()
+        # Force-kill the worker if it's still running. Needed when user code
+        # in the worker is stuck and won't notice the parent closing the RPC
+        # socket on its own.
+        if self._process is not None and self._process.poll() is None:
+            try:
+                self._process.terminate()
+            except Exception:
+                pass
 

src/testium/interpreter/utils/py_process.py

@@ -61,14 +61,18 @@ class PyProcessBase:
         if sock is not None:
             sock.close()
 
-        # Add the path of the subprocess (root sources of testium)
-        tstium_path = os.path.realpath(testium_path())
-        func_proc_path = os.path.realpath(subproc_path())
+        # In Flatpak the host can't see /app/lib/testium, so use a staged copy
+        # under /tmp (shared between sandbox and host) for both cwd and as the
+        # root in PYTHONPATH. Outside Flatpak the original paths are used.
+        if bins._in_flatpak():
+            tstium_path = bins._get_host_testium_path()
+            func_proc_path = tstium_path
+        else:
+            tstium_path = os.path.realpath(testium_path())
+            func_proc_path = os.path.realpath(subproc_path())
         env["PYTHONPATH"] = tstium_path + os.pathsep + self._ppath + os.pathsep + env.get("PYTHONPATH", "")
 
-        params = [
-            self._pbin,
-            # "-m",
+        cmd_args = [
             "py_func",
             "-p",
             f"{self._port}",
@@ -77,14 +81,31 @@ class PyProcessBase:
         ]
 
         if tm.debug_enabled() and tm.gd("debug_rpc", False):
-            params.append("-v")
+            cmd_args.append("-v")
+
+        if bins._in_flatpak():
+            # Run on the host outside the sandbox: avoids glibc ABI mismatches
+            # between the Flatpak runtime and host shared libraries.
+            host_env = {
+                k: env[k] for k in ("PYTHONPATH", "PATH")
+                if k in env and env[k]
+            }
+            params = bins.flatpak_host_spawn(
+                self._pbin, cmd_args, host_cwd=func_proc_path,
+                extra_env=host_env,
+            )
+            popen_kwargs = {}
+        else:
+            params = [self._pbin, *cmd_args]
+            popen_kwargs = {"env": env, "cwd": func_proc_path}
 
         self._process = subprocess.Popen(
-            params, env=env, cwd=func_proc_path,
+            params,
             stdin=subprocess.DEVNULL,
             stdout=subprocess.PIPE,
             stderr=subprocess.PIPE,
             restore_signals=False,
+            **popen_kwargs,
         )
         # Route subprocess stdout/stderr (early-startup errors,
         # unhandled exceptions, anything written to fd 1/2 before the
@@ -123,3 +144,11 @@ class PyProcessBase:
     def stop(self):
         if self._rpc is not None:
             self._rpc.stop()
+        # Force-kill the worker if it's still running. Needed when user code
+        # in the worker is stuck (e.g. sleep, blocking I/O) and won't notice
+        # the parent closing the RPC socket on its own.
+        if self._process is not None and self._process.poll() is None:
+            try:
+                self._process.terminate()
+            except Exception:
+                pass

src/testium/interpreter/utils/test_init.py

@@ -165,11 +165,14 @@ def env_init():
     _constants_init()
 
 
-def update_global(config_files, defines, gui_defaults, silent=False):
-    """Global dict updated with the content of the config file and a dict provided.
-    this function returns the resulting dict.
+def apply_overrides(defines, gui_defaults):
+    """Push GUI defaults then CLI defines into the global dict.
+
+    Extracted from update_global so it can be called *before* eval_proc
+    starts: interpreter overrides (python_bin, lua_bin) must be visible
+    to bins.python_bin() on its first lookup, which happens during
+    eval_process_init.
     """
-    # GUI preferences applied first
     for k, v in gui_defaults.items():
         try:
             val = ast.literal_eval(v)
@@ -177,7 +180,6 @@ def update_global(config_files, defines, gui_defaults, silent=False):
             val = v
         tm.setgd(k, val)
 
-    # Then command line defines
     for k, v in defines.items():
         try:
             val = ast.literal_eval(v)
@@ -185,6 +187,14 @@ def update_global(config_files, defines, gui_defaults, silent=False):
             val = v
         tm.setgd(k, val)
 
+
+def update_global(config_files, defines, gui_defaults, silent=False):
+    """Global dict updated with the content of the config file and a dict provided.
+    this function returns the resulting dict.
+    """
+    # GUI preferences applied first, then command line defines
+    apply_overrides(defines, gui_defaults)
+
     # Then the configuration files
     # load global dic before test item
     _feed_gd_with_params(config_files, silent)

src/testium/lua_func/json-rpc.lua

@@ -41,8 +41,7 @@ end
 --- INTERNAL: Handle requests from the client
 function JSONRPC:_handle_request(req)
     local method = self.methods[req.method]
-    local ok, ret
-    local res, err
+    local ok, ret, err
     if not method then
         if req.id then self:_send_error(req.id, string.format("Method '%s' not registered in lua server")) end
         return
@@ -52,15 +51,18 @@ function JSONRPC:_handle_request(req)
 
     -- Only send response if it's not a Notification (notifications have no ID)
     if req.id then
-        if ok then
-            res = ret
-            if res == nil then
-                self:_send_error(req.id, tostring(err))
-            else
-                self:_send({ jsonrpc = "2.0", result = { returned_value = res }, id = req.id })
-            end
-        else
+        if not ok then
+            -- pcall trapped a runtime error in the method itself.
+            self:_send_error(req.id, tostring(ret))
+        elseif err ~= nil then
+            -- Method ran but signaled a logical error via its 2nd return.
             self:_send_error(req.id, tostring(err))
+        else
+            -- Success. A user function returning nothing yields ret==nil;
+            -- encode it as JSON null so "returned_value" stays present.
+            local val = ret
+            if val == nil then val = json.null end
+            self:_send({ jsonrpc = "2.0", result = { returned_value = val }, id = req.id })
         end
     end
 end

src/testium/main_win/file_dialog.py

@@ -0,0 +1,21 @@
+"""Helpers for Qt file/directory dialogs.
+
+In Flatpak the native QFileDialog goes through the XDG document portal,
+which returns ``/run/user/UID/doc/.../<file>`` and only exposes the
+selected file — sibling files (param.yaml, scripts, recent paths in
+preferences, ...) are unreachable. Forcing Qt's own non-native dialog
+makes it walk the real filesystem mounted via ``--filesystem=home``
+and return a regular path.
+"""
+
+import os
+
+from PySide6.QtWidgets import QFileDialog
+
+
+def options():
+    """Default ``QFileDialog`` options for the current runtime."""
+    opts = QFileDialog.Options()
+    if os.path.isfile("/.flatpak-info"):
+        opts |= QFileDialog.Option.DontUseNativeDialog
+    return opts

src/testium/main_win/preference_win/preference_win.py

@@ -3,6 +3,7 @@ from PySide6.QtWidgets import QDialog, QFileDialog
 from PySide6.QtGui import QFont
 
 from main_win.preference_win.preference_core_win import Ui_preferenceWindow
+from main_win import file_dialog
 
 import interpreter.utils.settings as prefs
 
@@ -193,6 +194,7 @@ class PrefWindow(QDialog):
             self,
             caption="Select the default report directory",
             dir=self.ui.editDefaultReportPath.text(),
+            options=file_dialog.options(),
         )
         if path:
             self.ui.editDefaultReportPath.setText(path)
@@ -203,6 +205,7 @@ class PrefWindow(QDialog):
             self,
             caption="Select the default log directory",
             dir=self.ui.editDefaultLogPath.text(),
+            options=file_dialog.options(),
         )
         if path:
             self.ui.editDefaultLogPath.setText(path)
@@ -213,6 +216,7 @@ class PrefWindow(QDialog):
             self,
             caption="Select the python interpreter",
             dir=self.ui.editPythonPath.text(),
+            options=file_dialog.options(),
         )
         if path:
             self.ui.editPythonPath.setText(path)
@@ -220,7 +224,10 @@ class PrefWindow(QDialog):
     @Slot()
     def on_butLuaPath_pressed(self):
         path, _ = QFileDialog.getOpenFileName(
-            self, caption="Select the lua interpreter", dir=self.ui.editLuaPath.text()
+            self,
+            caption="Select the lua interpreter",
+            dir=self.ui.editLuaPath.text(),
+            options=file_dialog.options(),
         )
         if path:
             self.ui.editLuaPath.setText(path)

src/testium/main_win/test_file_manager.py

@@ -9,6 +9,7 @@ from PySide6.QtWidgets import QApplication, QFileDialog, QProgressDialog
 from interpreter.process import TestProcess
 from interpreter.utils.test_ctrl import TestSetController
 from main_win.test_controller_service import TestControllerService
+from main_win import file_dialog
 import interpreter.utils.settings as prefs
 from runtime.tum_except import ETUMFileError, ETUMRuntimeError
 
@@ -212,17 +213,9 @@ class TestFileManager:
         d = ""
         if w.testFile is not None:
             d = os.path.dirname(w.testFile)
-        # In Flatpak the native dialog goes through the XDG document portal,
-        # which returns /run/user/UID/doc/.../test.tum and only exposes the
-        # selected file — sibling files (param.yaml, .py, etc.) are unreachable.
-        # Force Qt's own dialog, which walks the real filesystem mounted via
-        # --filesystem=home and returns a regular path with sibling access.
-        options = QFileDialog.Options()
-        if os.path.isfile("/.flatpak-info"):
-            options |= QFileDialog.Option.DontUseNativeDialog
         file_name, _ = QFileDialog.getOpenFileName(
             w, "Open the test file", d,
-            "testium file (*.tum);;All Files (*)", options=options
+            "testium file (*.tum);;All Files (*)", options=file_dialog.options()
         )
         if file_name:
             self.reload(file_name)

src/testium/main_win/test_runner.py

@@ -176,7 +176,7 @@ class TestRunner:
             w.actionOpenTest.setDisabled(True)
             w.actionExit.setDisabled(True)
             icon = QtGui.QIcon()
-            icon.addPixmap(QtGui.QPixmap(icon_prefix() + "/pause.png"), QtGui.QIcon.Normal, QtGui.QIcon.Off)
+            icon.addPixmap(QtGui.QPixmap(icon_prefix() + "/pause2.png"), QtGui.QIcon.Normal, QtGui.QIcon.On)
             w.actionStart_test.setIcon(icon)
             w.actionStart_test.setText("Pause test")
             w.actionPreferences.setDisabled(True)

src/testium/main_win/testium_win.py

@@ -37,6 +37,7 @@ from interpreter.utils.icons import icon_prefix
 
 from main_win.test_run.outlog import OutLog
 from main_win.test_run.test_run import ThreadTestStatus
+from main_win import file_dialog
 import interpreter.utils.settings as prefs
 from runtime.stdout_redirect import stdio_redir
 import api.testium as tm
@@ -484,7 +485,8 @@ class MainWindow(QMainWindow, Ui_MainWindow):
         else:
             initialPath = None
         fileName, _ = QFileDialog.getSaveFileName(
-            self, "Path to Log file", initialPath, "Log Files (*.log);;All Files (*)"
+            self, "Path to Log file", initialPath, "Log Files (*.log);;All Files (*)",
+            options=file_dialog.options(),
         )
         if fileName:
             shutil.copy(self.logFileName, fileName)
@@ -525,7 +527,8 @@ class MainWindow(QMainWindow, Ui_MainWindow):
         else:
             initialPath = None
         fileName, _ = QFileDialog.getSaveFileName(
-            self, "Path to log file", initialPath, "Log Files (*.log);;All Files (*)"
+            self, "Path to log file", initialPath, "Log Files (*.log);;All Files (*)",
+            options=file_dialog.options(),
         )
         if fileName:
             self.editLogFilePath.setText(fileName)

src/testium/runtime/jrpc.py

@@ -200,6 +200,7 @@ class JsonRpcConnection:
 
         Raises:
             TimeoutError: If no response is received within `timeout`.
+            ConnectionAbortedError: If stop() was called while waiting.
         """
 
         req_id = next(self.id_gen)
@@ -214,7 +215,12 @@ class JsonRpcConnection:
             self.pending.pop(req_id, None)
             raise TimeoutError("Timeout JSON-RPC")
 
-        return self.pending.pop(req_id)["response"]
+        entry = self.pending.pop(req_id)
+        if entry["response"] is None:
+            # Woken by stop() (or by a malformed dispatch) rather than by a
+            # real response — abort the call so callers don't block further.
+            raise ConnectionAbortedError("JSON-RPC client stopped")
+        return entry["response"]
 
     def print_info(self, msg):
         if self.dbg_out is not None:
@@ -223,6 +229,10 @@ class JsonRpcConnection:
     def stop(self):
         if self.running:
             self.running = False
+        # Wake any in-flight call() so it doesn't sit on its (default 1h)
+        # timeout. The response stays None and call() raises ConnectionAbortedError.
+        for entry in list(self.pending.values()):
+            entry["event"].set()
 
     def join(self):
         self.recv_thread.join()

test/validation/README.md

@@ -1,10 +1,76 @@
 # Validation
 
-This directory contains the necessary material to run the testium validation.
+This directory contains the testium validation suite. A single set of
+items (`items/`), fixtures and post-processing (`post_execution.py`) is
+re-used across every packaging channel.
 
-Here is the documentation on how to configure the validation, run it and check that the
-results are correct.
+## Running the suite
 
-# Tests
+```sh
+./test/validation/run.sh                       # default mode = source
+./test/validation/run.sh --mode wheel
+./test/validation/run.sh --mode pyinstaller
+./test/validation/run.sh --mode flatpak
+./test/validation/run.sh --mode appimage
+```
 
-TBD
+On Windows (only `source`, `wheel`, `pyinstaller` are supported):
+
+```bat
+test\validation\run.bat --mode pyinstaller
+```
+
+Pass `clean` as the **first** argument to recreate the validation venv
+from scratch (useful after a system Python upgrade):
+
+```sh
+./test/validation/run.sh clean --mode flatpak
+```
+
+Any extra arguments after the mode flag are forwarded to testium.
+
+## Modes
+
+| Mode          | What it launches                                            | Prerequisite                                                     |
+|---------------|-------------------------------------------------------------|------------------------------------------------------------------|
+| `source`      | `python3 src/testium` via the project's `run.sh`            | none — works straight out of the repo                            |
+| `wheel`       | `python -m testium` inside a dedicated wheel venv           | `./build_all.sh` produced `dist/testium-<v>-py3-none-any.whl`    |
+| `pyinstaller` | `dist/testium-<v>` (frozen binary)                          | `./build_all.sh` produced the PyInstaller binary                 |
+| `flatpak`     | `flatpak run --command=testium org.testium.Testium`         | the Flatpak bundle is installed (`flatpak install --user dist/testium-<v>.flatpak`) |
+| `appimage`    | `dist/Testium-<v>-x86_64.AppImage`                          | `./build_all.sh` produced the AppImage                           |
+
+Each mode writes its results to a distinct report file
+(`validation-<mode>.sqlite` / `validation-<mode>-<item>.xml`), so you
+can run several modes in a row without clobbering previous reports.
+
+## How `python_bin` is pinned
+
+Every test-execution subprocess (inline `<| ... |>` evaluation,
+`py_func`, `cycle`, `post_execution`, …) is routed through a dedicated
+venv at `${TMPDIR:-/tmp}/testium-validation-venv`. The venv is created
+with `--system-site-packages` so existing system packages stay visible,
+then `junit-xml` is pip-installed for `post_execution.py`.
+
+This is a **host** venv. In every mode (including Flatpak) the
+test-execution subprocesses end up running on the host — directly for
+source/wheel/pyinstaller/appimage, and via `flatpak-spawn --host` for
+Flatpak — so the same venv works across modes. The wheel mode
+additionally creates a separate `testium-wheel-venv-<v>` to hold the
+installed wheel; that one is only used to launch testium itself.
+
+## What is checked
+
+The `venv` item under `items/venv/` asserts that the validation venv is
+actually being used:
+
+* `python_bin` is set in the global dict.
+* The eval subprocess (used for `<| ... |>` expressions) has
+  `sys.executable == python_bin`, `sys.prefix == dirname(dirname(python_bin))`,
+  and `sys.prefix != sys.base_prefix` (i.e. is actually inside a venv).
+* A `py_func` subprocess passes the same three checks.
+
+These checks use `abspath`/`normpath` rather than `realpath` on
+purpose: the venv's `bin/python3` is a symlink to the host interpreter,
+so `realpath` would map both venv and non-venv interpreters to the same
+target. `sys.prefix != sys.base_prefix` is the venv-specific marker
+that distinguishes the two cases.

test/validation/items/lua_func/lua_func.lua

@@ -49,4 +49,12 @@ function module.test_delgd()
     return 0
 end
 
+function module.return_nothing()
+    -- Returns no value: ret is nil but no error.
+end
+
+function module.return_explicit_nil()
+    return nil
+end
+
 return module

test/validation/items/lua_func/test.tum

@@ -186,6 +186,18 @@
     file: $(test_path)$(psep)lua_func.lua
     func_name: test_delgd
 
+- lua_func:
+    name: function returning nothing should succeed
+    key: $(test)_PASS
+    file: $(test_path)$(psep)lua_func.lua
+    func_name: return_nothing
+
+- lua_func:
+    name: function returning explicit nil should succeed
+    key: $(test)_PASS
+    file: $(test_path)$(psep)lua_func.lua
+    func_name: return_explicit_nil
+
 - group:
     name: context_id tests
     steps:

test/validation/items/py_func/py_func.py

@@ -54,3 +54,10 @@ def test_delgd():
     tm.delgd("_py_delgd_test")
     assert tm.gd("_py_delgd_test", None) is None
     return 0
+
+def return_nothing():
+    # Falls off the end: implicit None return, no error.
+    pass
+
+def return_explicit_none():
+    return None

test/validation/items/py_func/test.tum

@@ -196,6 +196,18 @@
     file: $(test_path)$(psep)py_func.py
     func_name: test_delgd
 
+- py_func:
+    name: function returning nothing should succeed
+    key: $(test)_PASS
+    file: $(test_path)$(psep)py_func.py
+    func_name: return_nothing
+
+- py_func:
+    name: function returning explicit None should succeed
+    key: $(test)_PASS
+    file: $(test_path)$(psep)py_func.py
+    func_name: return_explicit_none
+
 - group:
     name: context_id tests
     steps:

test/validation/items/venv/param.yaml

@@ -0,0 +1 @@
+no_param: Null

test/validation/items/venv/test.tum

@@ -0,0 +1,53 @@
+# venv test: assert that the dedicated validation venv is the python
+# being used for every test-execution subprocess (eval_proc / py_func /
+# cycle / ...). The venv path is pinned by ``-d python_bin=...`` in
+# test/validation/run.sh (or run.bat).
+#
+# We use ``abspath``/``normpath`` rather than ``realpath`` on purpose:
+# the venv's ``bin/python3`` is a symlink to the host python, so
+# realpath would map every venv interpreter to the same system path and
+# the comparison would silently pass even *without* a venv.
+# ``sys.prefix != sys.base_prefix`` is the venv-specific marker that
+# catches that case.
+
+- check:
+    name: python_bin is set in the global dict
+    key: $(test)_PASS
+    values:
+        - <| bool(r"$(python_bin)") |>
+
+- check:
+    name: eval_proc subprocess runs in the validation venv
+    key: $(test)_PASS
+    values:
+        - <| os.path.normpath(os.path.abspath(sys.executable)) == os.path.normpath(os.path.abspath(r"$(python_bin)")) |>
+
+- check:
+    name: eval_proc sys.prefix matches python_bin venv root
+    key: $(test)_PASS
+    values:
+        - <| os.path.normpath(os.path.abspath(sys.prefix)) == os.path.dirname(os.path.dirname(os.path.normpath(os.path.abspath(r"$(python_bin)")))) |>
+
+- check:
+    name: eval_proc is actually inside a venv (sys.prefix != sys.base_prefix)
+    key: $(test)_PASS
+    values:
+        - <| os.path.normpath(os.path.abspath(sys.prefix)) != os.path.normpath(os.path.abspath(sys.base_prefix)) |>
+
+- py_func:
+    name: py_func subprocess runs in the validation venv
+    key: $(test)_PASS
+    file: $(test_path)$(psep)verify_venv.py
+    func_name: check_sys_executable
+
+- py_func:
+    name: py_func sys.prefix matches python_bin venv root
+    key: $(test)_PASS
+    file: $(test_path)$(psep)verify_venv.py
+    func_name: check_sys_prefix_in_venv
+
+- py_func:
+    name: py_func is actually inside a venv
+    key: $(test)_PASS
+    file: $(test_path)$(psep)verify_venv.py
+    func_name: check_is_venv

test/validation/items/venv/verify_venv.py

@@ -0,0 +1,62 @@
+import os
+import sys
+
+import py_func.tm as tm
+
+
+def _norm(p):
+    # normpath + normcase, without resolving symlinks. realpath() would
+    # follow the venv's ``python3`` symlink to ``/usr/bin/python3.X`` and
+    # defeat the comparison.
+    return os.path.normcase(os.path.normpath(os.path.abspath(p)))
+
+
+def _venv_dir():
+    # python_bin is at ``<venv>/(bin|Scripts)/python*`` so the venv root
+    # is two levels above the executable.
+    exe = tm.gd("python_bin", "")
+    if not exe:
+        return ""
+    return os.path.dirname(os.path.dirname(_norm(exe)))
+
+
+def check_sys_executable():
+    """py_func subprocess: sys.executable must match the configured python_bin."""
+    expected = _norm(tm.gd("python_bin", ""))
+    actual = _norm(sys.executable)
+    if expected and actual == expected:
+        return True
+    return (
+        -1,
+        f"sys.executable={actual!r} differs from python_bin={expected!r}",
+    )
+
+
+def check_sys_prefix_in_venv():
+    """py_func subprocess: sys.prefix must match the venv root derived
+    from python_bin (two levels up from the executable)."""
+    venv = _venv_dir()
+    if not venv:
+        return (-1, "python_bin is not set in the global dict")
+    actual = _norm(sys.prefix)
+    if actual == venv:
+        return True
+    return (
+        -1,
+        f"sys.prefix={actual!r} is not the validation venv {venv!r}",
+    )
+
+
+def check_is_venv():
+    """py_func subprocess: confirm we are inside a venv, i.e. sys.prefix
+    differs from sys.base_prefix. This catches the case where python_bin
+    happens to be a system interpreter and the path-based check would
+    pass trivially."""
+    actual = _norm(sys.prefix)
+    base = _norm(sys.base_prefix)
+    if actual != base:
+        return True
+    return (
+        -1,
+        f"sys.prefix == sys.base_prefix == {actual!r}: not running in a venv",
+    )

test/validation/run.bat

@@ -0,0 +1,131 @@
+@echo off
+SETLOCAL EnableExtensions EnableDelayedExpansion
+
+REM Runs the testium validation suite against any installable channel of
+REM testium on Windows (source, wheel, pyinstaller).
+REM
+REM Usage:
+REM   test\validation\run.bat [clean] [--mode MODE] [extra testium args]
+REM
+REM   clean       remove the validation venv before recreating it
+REM               (must be the first argument; useful after a Python upgrade)
+REM
+REM   --mode MODE which testium build to validate. One of:
+REM                   source       (default) project's run.bat (src\testium)
+REM                   wheel        dist\testium-<v>-py3-none-any.whl
+REM                   pyinstaller  dist\testium-<v>.exe (or dist\testium-<v>)
+REM
+REM Every test-execution subprocess runs in a dedicated host venv under
+REM %TEMP%\testium-validation-venv (created with --system-site-packages,
+REM then junit-xml is pip-installed for post_execution.py).
+REM
+REM The report file is suffixed with the mode so consecutive runs in
+REM different modes don't overwrite each other.
+
+SET "SCRIPT_DIR=%~dp0"
+IF "%SCRIPT_DIR:~-1%"=="\" SET "SCRIPT_DIR=%SCRIPT_DIR:~0,-1%"
+SET "PROJECT_DIR=%SCRIPT_DIR%\..\.."
+SET /P VERSION=<"%PROJECT_DIR%\src\VERSION"
+
+REM ---------- arg parsing ----------------------------------------------------
+
+SET "MODE=source"
+SET "CLEAN=0"
+IF /I "%~1"=="clean" (
+    SET "CLEAN=1"
+    SHIFT
+)
+
+SET "EXTRA="
+:PARSE_ARGS
+IF "%~1"=="" GOTO ARGS_DONE
+IF /I "%~1"=="--mode" (
+    SET "MODE=%~2"
+    SHIFT
+    SHIFT
+    GOTO PARSE_ARGS
+)
+SET "EXTRA=!EXTRA! "%~1""
+SHIFT
+GOTO PARSE_ARGS
+:ARGS_DONE
+
+REM ---------- locate host python ---------------------------------------------
+
+SET "PYTHON_EXE="
+py --version >nul 2>&1
+IF %ERRORLEVEL% EQU 0 (
+    SET "PYTHON_EXE=py"
+    GOTO PYTHON_FOUND
+)
+python --version >nul 2>&1
+IF %ERRORLEVEL% EQU 0 (
+    SET "PYTHON_EXE=python"
+    GOTO PYTHON_FOUND
+)
+echo ERROR: Python could not be found on this system.
+exit /b 1
+:PYTHON_FOUND
+
+REM ---------- validation venv -------------------------------------------------
+
+SET "VENV_DIR=%TEMP%\testium-validation-venv"
+IF "%CLEAN%"=="1" IF EXIST "%VENV_DIR%" rmdir /s /q "%VENV_DIR%"
+
+IF NOT EXIST "%VENV_DIR%" (
+    echo Creating validation venv at %VENV_DIR%
+    %PYTHON_EXE% -m venv --system-site-packages "%VENV_DIR%"
+    IF !ERRORLEVEL! NEQ 0 (
+        echo ERROR while creating the validation venv.
+        exit /b 1
+    )
+    call "%VENV_DIR%\Scripts\pip" install --quiet --upgrade pip
+    call "%VENV_DIR%\Scripts\pip" install --quiet junit-xml
+)
+SET "VENV_PYTHON=%VENV_DIR%\Scripts\python.exe"
+
+REM ---------- shared "tail" forwarded to every launcher -----------------------
+REM Reports are stamped with the mode so successive runs don't clobber each other.
+
+SET "TAIL=-b -d "python_bin=%VENV_PYTHON%" -d "validation_report_file=validation-%MODE%" -- "%SCRIPT_DIR%\main.tum"%EXTRA%"
+
+REM ---------- per-mode launcher ----------------------------------------------
+
+echo -- validation mode: %MODE%
+
+IF /I "%MODE%"=="source"      GOTO MODE_SOURCE
+IF /I "%MODE%"=="wheel"       GOTO MODE_WHEEL
+IF /I "%MODE%"=="pyinstaller" GOTO MODE_PYI
+echo ERROR: unknown --mode '%MODE%'. Expected: source ^| wheel ^| pyinstaller.
+exit /b 1
+
+:MODE_SOURCE
+call "%PROJECT_DIR%\run.bat" %TAIL%
+exit /b %ERRORLEVEL%
+
+:MODE_WHEEL
+SET "WHEEL=%PROJECT_DIR%\dist\testium-%VERSION%-py3-none-any.whl"
+IF NOT EXIST "%WHEEL%" (
+    echo ERROR: wheel not found at %WHEEL% -- run build_all.sh first.
+    exit /b 1
+)
+SET "WHEEL_VENV=%TEMP%\testium-wheel-venv-%VERSION%"
+IF "%CLEAN%"=="1" IF EXIST "%WHEEL_VENV%" rmdir /s /q "%WHEEL_VENV%"
+IF NOT EXIST "%WHEEL_VENV%" (
+    echo Creating wheel venv at %WHEEL_VENV%
+    %PYTHON_EXE% -m venv --system-site-packages "%WHEEL_VENV%"
+    call "%WHEEL_VENV%\Scripts\pip" install --quiet --upgrade pip
+    call "%WHEEL_VENV%\Scripts\pip" install --quiet "%WHEEL%"
+)
+"%WHEEL_VENV%\Scripts\python.exe" -m testium %TAIL%
+exit /b %ERRORLEVEL%
+
+:MODE_PYI
+SET "PYI_BIN=%PROJECT_DIR%\dist\testium-%VERSION%.exe"
+IF NOT EXIST "%PYI_BIN%" SET "PYI_BIN=%PROJECT_DIR%\dist\testium-%VERSION%"
+IF NOT EXIST "%PYI_BIN%" (
+    echo ERROR: PyInstaller binary not found in %PROJECT_DIR%\dist -- run build_all.sh first.
+    exit /b 1
+)
+"%PYI_BIN%" %TAIL%
+exit /b %ERRORLEVEL%

test/validation/run.sh

@@ -0,0 +1,143 @@
+#!/bin/bash
+# Runs the testium validation suite against any installable channel of
+# testium (source, wheel, pyinstaller, flatpak, appimage).
+#
+# Usage:
+#   ./test/validation/run.sh [clean] [--mode MODE] [extra testium args]
+#
+#   clean           remove the validation venv before recreating it
+#                   (must be the first argument; useful after a Python upgrade)
+#
+#   --mode MODE     which testium build to validate. One of:
+#                       source       (default) src/testium via project run.sh
+#                       wheel        dist/testium-<v>-py3-none-any.whl
+#                       pyinstaller  dist/testium-<v>
+#                       flatpak      installed org.testium.Testium
+#                       appimage     dist/Testium-<v>-*.AppImage
+#
+# Every test-execution subprocess (inline <| ... |>, py_func, cycle,
+# post_execution, ...) runs in a dedicated host venv under
+# /tmp/testium-validation-venv. That venv is shared across modes —
+# even Flatpak reaches it via flatpak-spawn --host. The validation venv
+# is created with --system-site-packages so existing system packages
+# (PySide6, lxml, ...) stay visible, then junit-xml is pip-installed
+# for post_execution.py.
+#
+# The report file is suffixed with the mode (e.g. validation-flatpak.sqlite)
+# so consecutive runs in different modes don't overwrite each other.
+
+set -e
+
+SCRIPT_PATH="$(readlink -f "$0")"
+SCRIPT_DIR="$(realpath "$(dirname "$SCRIPT_PATH")")"
+PROJECT_DIR="$(realpath "$SCRIPT_DIR/../..")"
+VERSION="$(cat "$PROJECT_DIR/src/VERSION")"
+
+# ---------- arg parsing -------------------------------------------------------
+
+MODE=source
+
+if [ "${1:-}" = "clean" ]; then
+    CLEAN=1
+    shift
+else
+    CLEAN=0
+fi
+
+EXTRA=()
+while [ $# -gt 0 ]; do
+    case "$1" in
+        --mode)
+            MODE="$2"
+            shift 2
+            ;;
+        --mode=*)
+            MODE="${1#--mode=}"
+            shift
+            ;;
+        *)
+            EXTRA+=("$1")
+            shift
+            ;;
+    esac
+done
+
+# ---------- validation venv ---------------------------------------------------
+
+VENV_DIR="${TMPDIR:-/tmp}/testium-validation-venv"
+if [ "$CLEAN" -eq 1 ]; then
+    rm -rf "$VENV_DIR"
+fi
+
+if [ ! -d "$VENV_DIR" ]; then
+    echo "Creating validation venv at $VENV_DIR"
+    python3 -m venv --system-site-packages "$VENV_DIR"
+    "$VENV_DIR/bin/pip" install --quiet --upgrade pip
+    "$VENV_DIR/bin/pip" install --quiet junit-xml
+fi
+VENV_PYTHON="$VENV_DIR/bin/python3"
+
+# ---------- per-mode launcher -------------------------------------------------
+
+case "$MODE" in
+    source)
+        CMD=("$PROJECT_DIR/run.sh")
+        ;;
+    wheel)
+        WHEEL="$PROJECT_DIR/dist/testium-${VERSION}-py3-none-any.whl"
+        if [ ! -f "$WHEEL" ]; then
+            echo "ERROR: wheel not found at $WHEEL — run ./build_all.sh first." >&2
+            exit 1
+        fi
+        WHEEL_VENV="${TMPDIR:-/tmp}/testium-wheel-venv-${VERSION}"
+        if [ "$CLEAN" -eq 1 ]; then
+            rm -rf "$WHEEL_VENV"
+        fi
+        if [ ! -d "$WHEEL_VENV" ]; then
+            echo "Creating wheel venv at $WHEEL_VENV"
+            python3 -m venv --system-site-packages "$WHEEL_VENV"
+            "$WHEEL_VENV/bin/pip" install --quiet --upgrade pip
+            "$WHEEL_VENV/bin/pip" install --quiet "$WHEEL"
+        fi
+        CMD=("$WHEEL_VENV/bin/python" -m testium)
+        ;;
+    pyinstaller)
+        PYI_BIN="$PROJECT_DIR/dist/testium-${VERSION}"
+        if [ ! -x "$PYI_BIN" ]; then
+            echo "ERROR: PyInstaller binary not found at $PYI_BIN — run ./build_all.sh first." >&2
+            exit 1
+        fi
+        CMD=("$PYI_BIN")
+        ;;
+    flatpak)
+        if ! flatpak info --user org.testium.Testium &>/dev/null \
+           && ! flatpak info --system org.testium.Testium &>/dev/null; then
+            echo "ERROR: org.testium.Testium is not installed." >&2
+            echo "       flatpak install --user $PROJECT_DIR/dist/testium-${VERSION}.flatpak" >&2
+            exit 1
+        fi
+        CMD=(flatpak run --command=testium org.testium.Testium)
+        ;;
+    appimage)
+        APPIMAGE=$(ls -1t "$PROJECT_DIR/dist"/Testium-"${VERSION}"-*.AppImage 2>/dev/null | head -1)
+        if [ -z "$APPIMAGE" ] || [ ! -x "$APPIMAGE" ]; then
+            echo "ERROR: no AppImage for version $VERSION under $PROJECT_DIR/dist — run ./build_all.sh first." >&2
+            exit 1
+        fi
+        CMD=("$APPIMAGE")
+        ;;
+    *)
+        echo "ERROR: unknown --mode '$MODE'. Expected: source|wheel|pyinstaller|flatpak|appimage." >&2
+        exit 1
+        ;;
+esac
+
+# ---------- launch ------------------------------------------------------------
+
+echo "-- validation mode: $MODE"
+echo "-- launch: ${CMD[*]}"
+
+exec "${CMD[@]}" -b \
+    -d "python_bin=$VENV_PYTHON" \
+    -d "validation_report_file=validation-$MODE" \
+    -- "$SCRIPT_DIR/main.tum" "${EXTRA[@]}"