test(V2): migrazione test common/

Copiati e aggiornati i test da services/common/tests/ a tests/unit/common/.
Import aggiornati da mcp_common a cerbero_mcp.common. Eliminati test di
funzionalità V1-only (app_factory, environment, auth/Principal, server_base).
Refactored test_audit.py (principal→actor str) e test_mcp_bridge.py
(TokenStore→valid_tokens set). 71/71 test passano.

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

tests/unit/common/test_audit.py

@@ -0,0 +1,151 @@
+from __future__ import annotations
+
+import logging
+
+import pytest
+from cerbero_mcp.common import audit as audit_mod
+from cerbero_mcp.common.audit import audit_write_op
+
+
+@pytest.fixture
+def captured_records(monkeypatch):
+    """Cattura i record emessi dal logger mcp.audit (propagate=False blocca caplog).
+
+    Sostituisce il logger del modulo con uno che ha caplog attaccato.
+    """
+    records: list[logging.LogRecord] = []
+
+    class ListHandler(logging.Handler):
+        def emit(self, record: logging.LogRecord) -> None:
+            records.append(record)
+
+    test_logger = logging.getLogger("mcp.audit.test")
+    test_logger.handlers.clear()
+    test_logger.addHandler(ListHandler())
+    test_logger.setLevel(logging.DEBUG)
+    test_logger.propagate = False
+    monkeypatch.setattr(audit_mod, "_logger", test_logger)
+    return records
+
+
+def test_audit_write_op_emits_structured_record(captured_records):
+    audit_write_op(
+        actor="core",
+        action="place_order",
+        exchange="deribit",
+        target="BTC-PERPETUAL",
+        payload={"side": "buy", "amount": 10, "leverage": 3},
+        result={"order_id": "abc", "state": "open"},
+    )
+    assert len(captured_records) == 1
+    rec = captured_records[0]
+    assert rec.action == "place_order"
+    assert rec.exchange == "deribit"
+    assert rec.target == "BTC-PERPETUAL"
+    assert rec.actor == "core"
+    assert rec.payload == {"side": "buy", "amount": 10, "leverage": 3}
+    assert rec.result == {"order_id": "abc", "state": "open"}
+
+
+def test_audit_write_op_error_uses_error_level(captured_records):
+    audit_write_op(
+        actor="core",
+        action="cancel_order",
+        exchange="bybit",
+        target="ord-123",
+        payload={},
+        error="not_found",
+    )
+    assert len(captured_records) == 1
+    rec = captured_records[0]
+    assert rec.levelname == "ERROR"
+    assert rec.error == "not_found"
+
+
+def test_audit_write_op_summarizes_result_fields(captured_records):
+    big_result = {
+        "order_id": "ord-1",
+        "state": "submitted",
+        "extra_huge_field": "x" * 10000,
+        "orders": [{"id": 1}, {"id": 2}, {"id": 3}],
+    }
+    audit_write_op(
+        actor="core",
+        action="place_combo_order",
+        exchange="bybit",
+        payload={},
+        result=big_result,
+    )
+    rec = captured_records[0]
+    assert "extra_huge_field" not in rec.result
+    assert rec.result["order_id"] == "ord-1"
+    assert rec.result["orders_count"] == 3
+
+
+def test_audit_write_op_no_actor(captured_records):
+    audit_write_op(
+        actor=None,
+        action="place_order",
+        exchange="alpaca",
+        payload={},
+    )
+    rec = captured_records[0]
+    assert rec.actor is None
+
+
+def test_audit_write_op_writes_to_file_when_AUDIT_LOG_FILE_set(tmp_path, monkeypatch):
+    """Con env AUDIT_LOG_FILE settato, una riga JSON appare nel file."""
+    import json
+
+    from cerbero_mcp.common import audit as audit_mod
+
+    audit_file = tmp_path / "audit.jsonl"
+    monkeypatch.setenv("AUDIT_LOG_FILE", str(audit_file))
+    # Reset state idempotency flag così il test riesegue setup
+    audit_mod._file_handler_attached = False
+    # Pulisci handlers preesistenti dal logger (potrebbe avere file vecchio)
+    for h in list(audit_mod._logger.handlers):
+        from logging.handlers import TimedRotatingFileHandler
+        if isinstance(h, TimedRotatingFileHandler):
+            audit_mod._logger.removeHandler(h)
+
+    audit_write_op(
+        actor="core",
+        action="place_order",
+        exchange="bybit",
+        target="BTCUSDT",
+        payload={"side": "Buy", "qty": 0.01},
+        result={"order_id": "abc123", "status": "submitted"},
+    )
+
+    # Forza flush dei file handler
+    for h in audit_mod._logger.handlers:
+        h.flush()
+
+    assert audit_file.exists()
+    content = audit_file.read_text().strip()
+    assert content, "audit file empty"
+    record = json.loads(content.splitlines()[-1])
+    assert record["audit_event"] == "write_op"
+    assert record["action"] == "place_order"
+    assert record["exchange"] == "bybit"
+    assert record["target"] == "BTCUSDT"
+    assert record["actor"] == "core"
+
+
+def test_audit_no_file_when_env_unset(tmp_path, monkeypatch):
+    """Senza AUDIT_LOG_FILE, nessun file viene creato."""
+    from cerbero_mcp.common import audit as audit_mod
+    monkeypatch.delenv("AUDIT_LOG_FILE", raising=False)
+    audit_mod._file_handler_attached = False
+
+    audit_write_op(
+        actor="core",
+        action="cancel_order",
+        exchange="bybit",
+        target="ord-1",
+        payload={},
+    )
+    # Niente file creato in tmp_path
+    files = list(tmp_path.iterdir())
+    assert files == []