Refactor interface creation

oec/__main__.py

@@ -3,6 +3,7 @@ import time
 import signal
 import logging
 import argparse
+from contextlib import contextmanager
 from serial import Serial
 from coax import SerialInterface
 
@@ -32,6 +33,23 @@ def _get_keymap(terminal_id, extended_id):
 
     return keymap
 
+@contextmanager
+def _create_interface(args):
+    with Serial(args.serial_port, 115200) as serial:
+        serial.reset_input_buffer()
+        serial.reset_output_buffer()
+
+        # Allow the interface firmware time to start.
+        time.sleep(3)
+
+        interface = SerialInterface(serial)
+
+        firmware_version = interface.reset()
+
+        print(f'Interface firmware version {firmware_version}')
+
+        yield interface
+
 def _create_session(args, terminal):
     if args.emulator == 'tn3270':
         return TN3270Session(terminal, args.host, args.port)
@@ -83,21 +101,7 @@ def main():
 
     args = parser.parse_args()
 
-    with Serial(args.serial_port, 115200) as serial:
-        serial.reset_input_buffer()
-        serial.reset_output_buffer()
-
-        # Allow the interface firmware time to start.
-        time.sleep(3)
-
-        # Initialize the interface.
-        interface = SerialInterface(serial)
-
-        firmware_version = interface.reset()
-
-        print(f'Interface firmware version {firmware_version}')
-
-        # Initialize and start the controller.
+    with _create_interface(args) as interface:
         create_session = lambda terminal: _create_session(args, terminal)
 
         controller = Controller(interface, _get_keymap, create_session)