refactor: extract DirectAdminClient into directdnsonly.app.da module 🏗️

Move all outbound DirectAdmin HTTP logic out of ReconciliationWorker and
into a dedicated, independently testable DirectAdminClient class:

- directdnsonly/app/da/client.py: list_domains (paginated JSON + legacy
  fallback), get (authenticated GET to any CMD_* endpoint), _login
  (DA Evo session-cookie fallback), _parse_legacy_domain_list
- directdnsonly/app/da/__init__.py: public re-export of DirectAdminClient
- reconciler.py: now purely reconciliation logic; instantiates a client
  per configured server — no HTTP code remaining
- tests/test_da_client.py: 16 dedicated tests for DirectAdminClient
- tests/test_reconciler.py: mocks at the DirectAdminClient class boundary
  instead of the internal _fetch_da_domains method

Bumped to 2.2.0 — DirectAdminClient is now a first-class public API.

tests/test_da_client.py

@@ -0,0 +1,192 @@
+"""Tests for directdnsonly.app.da.client — DirectAdminClient."""
+
+import requests.exceptions
+from unittest.mock import MagicMock, patch
+
+from directdnsonly.app.da import DirectAdminClient
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+
+def _make_json_response(domains_list, total_pages=1):
+    data = {str(i): {"domain": d} for i, d in enumerate(domains_list)}
+    data["info"] = {"total_pages": total_pages}
+    mock = MagicMock()
+    mock.status_code = 200
+    mock.is_redirect = False
+    mock.headers = {"Content-Type": "application/json"}
+    mock.json.return_value = data
+    mock.raise_for_status = MagicMock()
+    return mock
+
+
+def _client():
+    return DirectAdminClient("da1.example.com", 2222, "admin", "secret", ssl=True, verify_ssl=True)
+
+
+# ---------------------------------------------------------------------------
+# list_domains — JSON happy path
+# ---------------------------------------------------------------------------
+
+
+def test_list_domains_returns_set_from_json():
+    mock_resp = _make_json_response(["example.com", "test.com"])
+
+    with patch("requests.get", return_value=mock_resp):
+        result = _client().list_domains()
+
+    assert result == {"example.com", "test.com"}
+
+
+def test_list_domains_paginates():
+    page1 = _make_json_response(["a.com"], total_pages=2)
+    page2 = _make_json_response(["b.com"], total_pages=2)
+
+    with patch("requests.get", side_effect=[page1, page2]):
+        result = _client().list_domains()
+
+    assert result == {"a.com", "b.com"}
+
+
+# ---------------------------------------------------------------------------
+# list_domains — DA Evo session login fallback
+# ---------------------------------------------------------------------------
+
+
+def test_redirect_triggers_session_login():
+    redirect_resp = MagicMock()
+    redirect_resp.status_code = 302
+    redirect_resp.is_redirect = True
+
+    client = _client()
+    with (
+        patch("requests.get", return_value=redirect_resp),
+        patch.object(client, "_login", return_value=False),
+    ):
+        result = client.list_domains()
+
+    assert result is None
+
+
+def test_persistent_redirect_after_login_returns_none():
+    redirect_resp = MagicMock()
+    redirect_resp.status_code = 302
+    redirect_resp.is_redirect = True
+
+    client = _client()
+    # Simulate cookies already set (login succeeded previously)
+    client._cookies = {"session": "abc"}
+
+    with patch("requests.get", return_value=redirect_resp):
+        result = client.list_domains()
+
+    assert result is None
+
+
+# ---------------------------------------------------------------------------
+# list_domains — error cases
+# ---------------------------------------------------------------------------
+
+
+def test_html_response_returns_none():
+    mock_resp = MagicMock()
+    mock_resp.status_code = 200
+    mock_resp.is_redirect = False
+    mock_resp.headers = {"Content-Type": "text/html; charset=utf-8"}
+    mock_resp.raise_for_status = MagicMock()
+
+    with patch("requests.get", return_value=mock_resp):
+        result = _client().list_domains()
+
+    assert result is None
+
+
+def test_connection_error_returns_none():
+    with patch("requests.get", side_effect=requests.exceptions.ConnectionError("refused")):
+        result = _client().list_domains()
+
+    assert result is None
+
+
+def test_timeout_returns_none():
+    with patch("requests.get", side_effect=requests.exceptions.Timeout()):
+        result = _client().list_domains()
+
+    assert result is None
+
+
+def test_ssl_error_returns_none():
+    with patch("requests.get", side_effect=requests.exceptions.SSLError("cert verify failed")):
+        result = _client().list_domains()
+
+    assert result is None
+
+
+# ---------------------------------------------------------------------------
+# _parse_legacy_domain_list
+# ---------------------------------------------------------------------------
+
+
+def test_parse_standard_querystring():
+    result = DirectAdminClient._parse_legacy_domain_list("list[]=example.com&list[]=test.com")
+    assert result == {"example.com", "test.com"}
+
+
+def test_parse_newline_separated():
+    result = DirectAdminClient._parse_legacy_domain_list("list[]=example.com\nlist[]=test.com")
+    assert result == {"example.com", "test.com"}
+
+
+def test_parse_empty_body_returns_empty_set():
+    assert DirectAdminClient._parse_legacy_domain_list("") == set()
+
+
+def test_parse_normalises_to_lowercase():
+    result = DirectAdminClient._parse_legacy_domain_list("list[]=EXAMPLE.COM")
+    assert "example.com" in result
+    assert "EXAMPLE.COM" not in result
+
+
+def test_parse_strips_whitespace():
+    result = DirectAdminClient._parse_legacy_domain_list("list[]= example.com ")
+    assert "example.com" in result
+
+
+# ---------------------------------------------------------------------------
+# _login
+# ---------------------------------------------------------------------------
+
+
+def test_login_stores_cookies_on_success():
+    mock_resp = MagicMock()
+    mock_resp.cookies = {"session": "tok123"}
+
+    client = _client()
+    with patch("requests.post", return_value=mock_resp):
+        result = client._login()
+
+    assert result is True
+    assert client._cookies == {"session": "tok123"}
+
+
+def test_login_returns_false_when_no_cookies():
+    mock_resp = MagicMock()
+    mock_resp.cookies = {}
+
+    client = _client()
+    with patch("requests.post", return_value=mock_resp):
+        result = client._login()
+
+    assert result is False
+    assert client._cookies is None
+
+
+def test_login_returns_false_on_exception():
+    client = _client()
+    with patch("requests.post", side_effect=requests.exceptions.ConnectionError()):
+        result = client._login()
+
+    assert result is False