feat: add TunnelConfig dataclass and YAML I/O

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

tests/conftest.py

@@ -0,0 +1,19 @@
+import pytest
+from autossh_mgr.config import TunnelConfig, ensure_dirs
+
+
+@pytest.fixture
+def config_dir(tmp_path):
+    ensure_dirs(tmp_path)
+    return tmp_path
+
+
+@pytest.fixture
+def sample_tunnel():
+    return TunnelConfig(
+        name="web-service",
+        host="relay.example.com",
+        user="deploy",
+        local_port=8080,
+        remote_port=18080,
+    )

tests/unit/test_config.py

@@ -0,0 +1,61 @@
+import pytest
+import click
+from autossh_mgr.config import (
+    TunnelConfig, ensure_dirs, load_tunnels, save_tunnels, get_tunnel
+)
+
+
+def test_ensure_dirs_creates_structure(tmp_path):
+    ensure_dirs(tmp_path)
+    assert (tmp_path / "tunnels.yaml").exists()
+    assert (tmp_path / "pids").is_dir()
+    assert (tmp_path / "logs").is_dir()
+
+
+def test_ensure_dirs_is_idempotent(tmp_path):
+    ensure_dirs(tmp_path)
+    ensure_dirs(tmp_path)  # must not raise
+
+
+def test_load_tunnels_empty(config_dir):
+    assert load_tunnels(config_dir) == []
+
+
+def test_save_and_load_roundtrip(config_dir, sample_tunnel):
+    save_tunnels(config_dir, [sample_tunnel])
+    loaded = load_tunnels(config_dir)
+    assert len(loaded) == 1
+    t = loaded[0]
+    assert t.name == "web-service"
+    assert t.host == "relay.example.com"
+    assert t.user == "deploy"
+    assert t.local_port == 8080
+    assert t.remote_port == 18080
+    assert t.port == 22
+    assert t.identity_file == "~/.ssh/id_ed25519"
+    assert t.local_host == "127.0.0.1"
+    assert t.remote_host == "0.0.0.0"
+    assert t.ssh_options == ""
+
+
+def test_save_atomic_write(config_dir, sample_tunnel):
+    save_tunnels(config_dir, [sample_tunnel])
+    # No .tmp file left behind
+    assert not (config_dir / "tunnels.yaml.tmp").exists()
+
+
+def test_get_tunnel_found(config_dir, sample_tunnel):
+    save_tunnels(config_dir, [sample_tunnel])
+    t = get_tunnel(config_dir, "web-service")
+    assert t.name == "web-service"
+
+
+def test_get_tunnel_not_found(config_dir):
+    with pytest.raises(click.ClickException, match="No tunnel named 'missing'"):
+        get_tunnel(config_dir, "missing")
+
+
+def test_get_config_dir_env_override(monkeypatch, tmp_path):
+    monkeypatch.setenv("AUTOSSH_MGR_CONFIG_DIR", str(tmp_path))
+    from autossh_mgr.config import get_config_dir
+    assert get_config_dir() == tmp_path