Fix application tester re-run failure

scripts/application_tester/main.py

@@ -48,6 +48,7 @@
         executor_kwargs['check_process_started_interval'] = 1
 
     executor = Executor(args, **executor_kwargs)
+    executor.set_core_api_port()
 
     loop = get_event_loop()
     coro = executor.start()

scripts/application_tester/tribler_apptester/executor.py

@@ -15,6 +15,7 @@
 from typing import Dict, Optional
 
 from tribler.core.config.tribler_config import TriblerConfig
+from tribler.core.utilities.network_utils import default_network_utils, FreePortNotFoundError
 from tribler_apptester.action_selector import ActionSelector
 from tribler_apptester.actions.shutdown_action import ShutdownAction
 from tribler_apptester.monitors.download_monitor import DownloadMonitor
@@ -32,6 +33,8 @@
 
 SHUTDOWN_TIMEOUT = 30
 
+DEFAULT_CORE_API_PORT = 20100
+
 
 class Executor(object):
 
@@ -42,7 +45,7 @@ def __init__(self, args, read_config_delay=2, read_config_attempts=10, check_pro
         self.check_process_started_interval = check_process_started_interval
         self.read_config_attempts = read_config_attempts
         self.code_port = args.codeport
-        self.api_port = int(os.environ.get('CORE_API_PORT'))
+        self.api_port = None
         self._logger = logging.getLogger(self.__class__.__name__)
         self.allow_plain_downloads = args.plain
         self.pending_tasks: Dict[bytes, Future] = {}  # Dictionary of pending tasks
@@ -65,6 +68,25 @@ def __init__(self, args, read_config_delay=2, read_config_attempts=10, check_pro
         self.request_manager = None
         self.action_selector = ActionSelector()
 
+    def set_core_api_port(self) -> None:
+        """
+        Set the core API port to a free port.
+        Prefer the port specified in the environment variable CORE_API_PORT.
+        Then update the environment variable CORE_API_PORT to match the port that was chosen.
+        """
+        base_api_port = int(os.environ.get('CORE_API_PORT', f"{DEFAULT_CORE_API_PORT}"))
+
+        try:
+            self.api_port = default_network_utils.get_first_free_port(start=base_api_port)
+            self._logger.info(f"Setting the Core API port to {self.api_port}")
+        except FreePortNotFoundError:
+            self._logger.error("Could not find a free port to use as Core API port.")
+            raise
+
+        # Update the environment variable CORE_API_PORT to the port that was chosen
+        # so that the Tribler process can use the correct port.
+        os.environ['CORE_API_PORT'] = str(self.api_port)
+
     async def start(self):
         await self.start_tribler()
 

scripts/application_tester/tribler_apptester/tests/test_executor.py

@@ -0,0 +1,53 @@
+import argparse
+import os
+import random
+from unittest.mock import MagicMock, patch
+
+import pytest
+
+from tribler_apptester.executor import DEFAULT_CORE_API_PORT, Executor
+from tribler.core.utilities.network_utils import FreePortNotFoundError
+
+
+@pytest.fixture(name='executor')
+def fixture_executor() -> Executor:
+    args = argparse.Namespace(
+        tribler_executable='python ./src/run_tribler.py',
+        plain=False,
+        duration=120,
+        silent=False,
+        codeport=5500,
+        monitordownloads=None,
+        monitorresources=None,
+        monitoripv8=None,
+        fragile=True
+    )
+    return Executor(args)
+
+
+@patch('os.environ', new={})
+@patch('tribler.core.utilities.network_utils.default_network_utils.get_first_free_port')
+@pytest.mark.parametrize("initial_core_api_port", [DEFAULT_CORE_API_PORT, 8085])
+def test_set_core_api_port_(mock_get_first_free_port: MagicMock, executor: Executor, initial_core_api_port):
+    assert executor.api_port is None
+
+    os.environ['CORE_API_PORT'] = str(initial_core_api_port)
+    next_available_free_port = initial_core_api_port + random.randint(0, 100)
+    mock_get_first_free_port.return_value = next_available_free_port
+
+    executor.set_core_api_port()
+
+    assert os.environ.get('CORE_API_PORT') == str(next_available_free_port)
+    assert executor.api_port == next_available_free_port
+
+
+@patch('os.environ', new={})
+@patch('tribler.core.utilities.network_utils.default_network_utils.get_first_free_port')
+def test_set_core_api_port_not_found(mock_get_first_free_port: MagicMock, executor: Executor):
+    assert executor.api_port is None
+
+    os.environ['CORE_API_PORT'] = str(DEFAULT_CORE_API_PORT)
+    mock_get_first_free_port.side_effect = FreePortNotFoundError('Free port not found')
+
+    with pytest.raises(FreePortNotFoundError):
+        executor.set_core_api_port()