validation: cover nil/None return from lua_func/py_func

Two new steps per language: function returning nothing and function
returning explicit nil/None. Both tagged $(test)_PASS — they would
have failed before the lua nil fix (Lua side reported nil result as
error). Python side already worked but is covered for parity.

DESIGN.md

@@ -1,4 +1,4 @@
-# Testium — Claude Context
+# Testium — Design Context
 
 ## What is testium
 

build_all.sh

@@ -1,13 +1,17 @@
 #!/bin/bash
 # Build every distribution channel of testium, in order:
-#   1. Wheel              -> dist/testium-<v>-py3-none-any.whl   (PEP 427 name)
+#   1. Manual PDF         -> dist/testium-manual-<v>.pdf
-#   2. PyInstaller binary -> dist/testium-<v>
+#   2. Wheel              -> dist/testium-<v>-py3-none-any.whl   (PEP 427 name)
-#   3. Flatpak bundle     -> dist/testium-<v>.flatpak
+#   3. PyInstaller binary -> dist/testium-<v>
-#   4. AppImage           -> dist/Testium-<v>-x86_64.AppImage    (original name)
+#   4. Flatpak bundle     -> dist/testium-<v>.flatpak
+#   5. AppImage           -> dist/Testium-<v>-x86_64.AppImage    (original name)
+# release_note.txt is copied to dist/ up front (with a warning if it has no
+# entry for the current version).
+#
 # All artifacts are collected (copied) under <repo>/dist/. Original outputs in
-# src/dist/, package/*/dist/ are left in place. The wheel and AppImage keep
+# src/dist/, package/*/dist/, doc/manual/ are left in place. Wheel and AppImage
-# their original names (which already contain the version); pyinstaller and
+# keep their original names (which already contain the version); manual,
-# flatpak are renamed to a normalized testium-<version>(.suff) form.
+# pyinstaller and flatpak are renamed to testium(-manual)-<version>(.suff).
 #
 # 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
@@ -22,6 +26,15 @@ VERSION=$(cat "$SCRIPT_DIR/src/VERSION")
 DIST_DIR="$SCRIPT_DIR/dist"
 mkdir -p "$DIST_DIR"
 
+# Release note: copy it to dist/ and warn (but don't fail) if it has no entry
+# for the current version.
+RELEASE_NOTE_SRC="$SCRIPT_DIR/release_note.txt"
+RELEASE_NOTE="$DIST_DIR/release_note.txt"
+cp -f "$RELEASE_NOTE_SRC" "$RELEASE_NOTE"
+if ! grep -qE "^version $VERSION([^.0-9]|$)" "$RELEASE_NOTE_SRC"; then
+    echo "WARNING: release_note.txt has no entry for version $VERSION." >&2
+fi
+
 export PY_VENV_NAME=".venv"
 export PY_VENV_DIR="$SCRIPT_DIR/test/tmp/$PY_VENV_NAME"
 export REQ_PATH="$SCRIPT_DIR/src/requirements.txt"
@@ -39,8 +52,15 @@ step() {
     echo "================================================================"
 }
 
-# 1. Wheel — PEP 427 name kept (already contains version)
+# 1. Manual PDF
-step "1/4  Wheel (version $VERSION)"
+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"
+
+# 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
@@ -50,15 +70,15 @@ WHEEL_SRC=$(ls -1t "$SCRIPT_DIR/src/dist"/*.whl | head -1)
 WHEEL="$DIST_DIR/$(basename "$WHEEL_SRC")"
 cp -f "$WHEEL_SRC" "$WHEEL"
 
-# 2. PyInstaller binary
+# 3. PyInstaller binary
-step "2/4  PyInstaller binary (version $VERSION)"
+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"
 
-# 3. Flatpak bundle
+# 4. Flatpak bundle
-step "3/4  Flatpak bundle (version $VERSION)"
+step "4/5  Flatpak bundle (version $VERSION)"
 (
     cd "$SCRIPT_DIR/package/flatpak"
     bash build.sh
@@ -67,8 +87,8 @@ FLATPAK_SRC="$SCRIPT_DIR/package/flatpak/testium.flatpak"
 FLATPAK_BUNDLE="$DIST_DIR/testium-${VERSION}.flatpak"
 cp -f "$FLATPAK_SRC" "$FLATPAK_BUNDLE"
 
-# 4. AppImage
+# 5. AppImage
-step "4/4  AppImage (version $VERSION)"
+step "5/5  AppImage (version $VERSION)"
 (
     cd "$SCRIPT_DIR/package/appimage"
     bash build.sh
@@ -79,7 +99,9 @@ cp -f "$APPIMAGE_SRC" "$APPIMAGE"
 chmod +x "$APPIMAGE"
 
 step "All packages built"
+printf "  manual       : %s\n" "$MANUAL"
 printf "  wheel        : %s\n" "$WHEEL"
 printf "  pyinstaller  : %s\n" "$PYI_BIN"
 printf "  flatpak      : %s\n" "$FLATPAK_BUNDLE"
 printf "  appimage     : %s\n" "$APPIMAGE"
+printf "  release_note : %s\n" "$RELEASE_NOTE"

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
 
@@ -11,3 +13,6 @@ def funcToBeExecuted (bla):
 def funcToBeExecuted2 (bla):
     print(bla)
     return blo
+
+def long_wait (sec):
+    sleep(sec)

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/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'')):
@@ -191,16 +188,21 @@ 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(STOP_POLL_INTERVAL)
-
-                data = self.readchar(timeout)
                     if data is not None:
                         data = self._compute_char(data)
                         if data != '':
@@ -210,7 +212,6 @@ A {classname}.close() is missing somewhere in your code !'.format(classname=type
 
                             search_deque.append(data)
                             if search_deque == match_deque:
-                            timer.cancel()
                                 status = 0
                                 if (not mute) and (data != '\n'):
                                     self.string_buffer += '\n'
@@ -224,6 +225,8 @@ A {classname}.close() is missing somewhere in your code !'.format(classname=type
 
                                 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/test_items/test_item.py

@@ -20,9 +20,26 @@ class TestItem:
 def test_run(f):
     @wraps(f)
     def wrapper(self):
-        if not self.skipped:
+        if self.skipped:
-            if self.enabled:
+            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
@@ -57,15 +74,10 @@ def test_run(f):
             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:
-            self.result.set(TestValue.NORUN, "test skipped")
-            print("Test is skipped.")
 
         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
@@ -311,6 +318,7 @@ class TestItem:
         self.report.addTest(self, self.result, rk)
         self._sendStatusFinished()
         
+
     def process_result(self):
         if self._post_eval is None:
             return

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
@@ -249,13 +257,23 @@ 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
-        # configures the reception timeout
+        # STOP_POLL_INTERVAL.
-        self.sock.settimeout(timeout)
+        self.sock.settimeout(STOP_POLL_INTERVAL)
-
+        deadline = time.monotonic() + float(timeout)
-        # Receives the answer from the server
+        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."
+                    )
 
         # In case of buffer overload we chose to complain
         if len(data) >= self._bufsize:
@@ -271,10 +289,6 @@ class JrpcUdpAdapter(JrpcAdapter):
             print(f"  | UDP answer: '{res}'")
             print(f"  | received from @{addr[0]}:{addr[1]}")
 
-        except socket.timeout:
-            raise ETUMRuntimeError(
-                "JSONRPC udp answer took too long. Try to increase the timeout."
-            )
         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(
@@ -96,8 +108,14 @@ 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())
+            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(
@@ -94,8 +106,14 @@ 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())
+            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_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()))
+            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/lua_process.py

@@ -146,4 +146,12 @@ 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

@@ -123,3 +123,11 @@ 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/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 ok, ret, err
-    local res, 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
+        if not ok then
-            res = ret
+            -- pcall trapped a runtime error in the method itself.
-            if res == nil then
+            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
-                self:_send({ jsonrpc = "2.0", result = { returned_value = res }, id = req.id })
+            -- Success. A user function returning nothing yields ret==nil;
-            end
+            -- encode it as JSON null so "returned_value" stays present.
-        else
+            local val = ret
-            self:_send_error(req.id, tostring(err))
+            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/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/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/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: