feat: add PID file utilities and tunnel status detection

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

tests/unit/test_process.py

@@ -0,0 +1,97 @@
+import os
+import pytest
+from datetime import datetime, timezone, timedelta
+from unittest.mock import patch
+from autossh_mgr.process import (
+    write_pid_file, read_pid_file, delete_pid_file,
+    is_process_alive, check_stale, get_status, format_uptime,
+    TunnelStatus,
+)
+
+
+def test_write_and_read_pid_file(config_dir):
+    started = datetime(2026, 5, 20, 10, 0, 0, tzinfo=timezone.utc)
+    write_pid_file(config_dir, "web-service", 12345, started)
+    pid, ts = read_pid_file(config_dir, "web-service")
+    assert pid == 12345
+    assert ts == started
+
+
+def test_read_pid_file_missing(config_dir):
+    assert read_pid_file(config_dir, "missing") is None
+
+
+def test_delete_pid_file(config_dir):
+    started = datetime.now(timezone.utc)
+    write_pid_file(config_dir, "web-service", 12345, started)
+    delete_pid_file(config_dir, "web-service")
+    assert read_pid_file(config_dir, "web-service") is None
+
+
+def test_delete_pid_file_missing_is_noop(config_dir):
+    delete_pid_file(config_dir, "missing")  # must not raise
+
+
+def test_is_process_alive_running():
+    # os.getpid() is always alive
+    assert is_process_alive(os.getpid()) is True
+
+
+def test_is_process_alive_dead():
+    assert is_process_alive(9999999) is False
+
+
+def test_check_stale_no_pid_file(config_dir):
+    assert check_stale(config_dir, "web-service") is False
+
+
+def test_check_stale_running_process(config_dir):
+    write_pid_file(config_dir, "web-service", os.getpid(), datetime.now(timezone.utc))
+    assert check_stale(config_dir, "web-service") is False
+
+
+def test_check_stale_dead_process(config_dir):
+    write_pid_file(config_dir, "web-service", 9999999, datetime.now(timezone.utc))
+    assert check_stale(config_dir, "web-service") is True
+
+
+def test_get_status_stopped(config_dir):
+    status = get_status(config_dir, "web-service")
+    assert status.state == "stopped"
+    assert status.pid is None
+    assert status.uptime is None
+
+
+def test_get_status_running(config_dir):
+    write_pid_file(config_dir, "web-service", os.getpid(), datetime.now(timezone.utc))
+    status = get_status(config_dir, "web-service")
+    assert status.state == "running"
+    assert status.pid == os.getpid()
+    assert status.uptime is not None
+
+
+def test_get_status_stale(config_dir):
+    write_pid_file(config_dir, "web-service", 9999999, datetime.now(timezone.utc))
+    status = get_status(config_dir, "web-service")
+    assert status.state == "stale"
+    assert status.pid == 9999999
+
+
+def test_format_uptime_seconds():
+    started = datetime.now(timezone.utc) - timedelta(seconds=45)
+    assert format_uptime(started) == "45s"
+
+
+def test_format_uptime_minutes():
+    started = datetime.now(timezone.utc) - timedelta(minutes=3, seconds=15)
+    assert format_uptime(started) == "3m"
+
+
+def test_format_uptime_hours():
+    started = datetime.now(timezone.utc) - timedelta(hours=2, minutes=30)
+    assert format_uptime(started) == "2h 30m"
+
+
+def test_format_uptime_days():
+    started = datetime.now(timezone.utc) - timedelta(days=1, hours=5)
+    assert format_uptime(started) == "1d 5h"