Duplicate test output to stdout/stderr

src/robotremoteserver.py

@@ -433,14 +433,28 @@ def _handle_binary(self, arg):
         return arg
 
 
+class StreamDuplicator(StringIO):
+    """
+    Duplicate stream to stream given as parameter and internal StringIO.
+    """
+
+    def __init__(self, stream):
+        self.other_stream = stream
+        super(StreamDuplicator, self).__init__()
+
+    def write(self, s):
+        self.other_stream.write(s)
+        return super(StreamDuplicator, self).write(s)
+
+
 class StandardStreamInterceptor(object):
 
     def __init__(self):
         self.output = ''
         self.origout = sys.stdout
         self.origerr = sys.stderr
-        sys.stdout = StringIO()
-        sys.stderr = StringIO()
+        sys.stdout = StreamDuplicator(self.origout)
+        sys.stderr = StreamDuplicator(self.origerr)
 
     def __enter__(self):
         return self

test/utest/test_serve.py

@@ -64,7 +64,8 @@ def _run_remote_keyword(self, uri):
         sys.stdout = StringIO()
         try:
             self.assertEqual(Remote(uri).run_keyword('kw', (), None), 42)
-            self.assertEqual(sys.stdout.getvalue(), 'The message!\n')
+            # Duplication of 'The message!\n' is expected as test and RobotRemoteServer run in same process.
+            self.assertEqual(sys.stdout.getvalue(), 'The message!\nThe message!\n')
         finally:
             sys.stdout.close()
             sys.stdout = origout