Avoid errors about signal handlers when running Robot on thread.

pekkaklarck · pekkaklarck · commit 97d6c6e855ad · 2014-12-09T00:53:08.000+02:00
Python doesn't allow non-main threads to register signal handlers. Robot already ignored errors registering handlers for SIGINT and SIGTERM if not run on the main thread. When registering the old handlers back after execution, these errors were shown on the console. This is fixed by checking are we on the main thread both before registering our own handlers before execution and also when resetting old handlers afterwards. Fixes robotframework#1848.
diff --git a/src/robot/running/signalhandler.py b/src/robot/running/signalhandler.py
@@ -54,26 +54,28 @@ def start(self):
         self.__enter__()
 
     def __enter__(self):
-        if signal:
+        if self._can_register_signal:
             self._orig_sigint = signal.getsignal(signal.SIGINT)
             self._orig_sigterm = signal.getsignal(signal.SIGTERM)
             for signum in signal.SIGINT, signal.SIGTERM:
                 self._register_signal_handler(signum)
         return self
 
     def __exit__(self, *exc_info):
-        if signal:
+        if self._can_register_signal:
             signal.signal(signal.SIGINT, self._orig_sigint)
             signal.signal(signal.SIGTERM, self._orig_sigterm)
 
+    @property
+    def _can_register_signal(self):
+        return signal and currentThread().getName() == 'MainThread'
+
     def _register_signal_handler(self, signum):
         try:
             signal.signal(signum, self)
         except (ValueError, IllegalArgumentException), err:
-            # ValueError occurs e.g. if Robot doesn't run on main thread.
-            # IllegalArgumentException is http://bugs.jython.org/issue1729
-            if currentThread().getName() == 'MainThread':
-                self._warn_about_registeration_error(signum, err)
+            # IllegalArgumentException due to http://bugs.jython.org/issue1729
+            self._warn_about_registeration_error(signum, err)
 
     def _warn_about_registeration_error(self, signum, err):
         name, ctrlc = {signal.SIGINT: ('INT', 'or with Ctrl-C '),
diff --git a/utest/api/test_run_and_rebot.py b/utest/api/test_run_and_rebot.py
@@ -1,5 +1,6 @@
 import unittest
 import sys
+import threading
 import tempfile
 import signal
 from os.path import abspath, dirname, join, exists, curdir
@@ -181,6 +182,15 @@ def test_original_signal_handlers_are_restored(self):
             signal.signal(signal.SIGINT, orig_sigint)
             signal.signal(signal.SIGTERM, orig_sigterm)
 
+    def test_dont_register_signal_handlers_then_run_on_thread(self):
+        stream = StringIO()
+        thread = threading.Thread(target=run_without_outputs, args=(self.data,),
+                                  kwargs=dict(stdout=stream, stderr=stream))
+        thread.start()
+        thread.join()
+        output = stream.getvalue()
+        assert_true('ERROR' not in output.upper(), 'Errors:\n%s' % output)
+
 
 class TestRelativeImportsFromPythonpath(RunningTestCase):
     _data = join(abspath(dirname(__file__)), 'import_test.robot')
