write tests for streamer

aircox_streamer/controllers/streamer.py

@@ -173,7 +173,7 @@ class Streamer:
 
         self.check_zombie_process()
         self.process = subprocess.Popen(args, stderr=subprocess.STDOUT)
-        atexit.register(lambda: self.kill_process())
+        atexit.register(self.kill_process)
 
     def kill_process(self):
         if self.process:
@@ -184,6 +184,7 @@ class Streamer:
             )
             self.process.kill()
             self.process = None
+            atexit.unregister(self.kill_process)
 
     def wait_process(self):
         """Wait for the process to terminate if there is a process."""