Implement testing the removal of IO pipes on server stop

pipe_io_server/pipe_io_server.py

@@ -55,5 +55,6 @@ class PipeIOServer(ABC):
 
     def stop(self):
         for thread in self._io_threads:
-            thread.stop()
+            if thread.isAlive():
+                thread.stop()
         PipeHandler(self.in_pipe, self.out_pipe).remove()

tests.py

@@ -44,6 +44,12 @@ def test_echo_server(pipe_io, test_data):
     assert File(pipe_io.out_pipe).read() == test_data
 
 
+def test_stop_removes_pipes(pipe_io):
+    pipe_io.stop()
+    for path in (pipe_io.in_pipe, pipe_io.out_pipe):
+        assert not exists(path)
+
+
 class File:
     def __init__(self, path):
         self.path = path