test: lazy-load LLM provider clients and add API-key fixtures so the test suite runs cleanly without credentials (#588)

tests/test_ticker_symbol_handling.py

@@ -1,9 +1,12 @@
 import unittest
 
+import pytest
+
 from cli.utils import normalize_ticker_symbol
 from tradingagents.agents.utils.agent_utils import build_instrument_context
 
 
+@pytest.mark.unit
 class TickerSymbolHandlingTests(unittest.TestCase):
     def test_normalize_ticker_symbol_preserves_exchange_suffix(self):
         self.assertEqual(normalize_ticker_symbol(" cnc.to "), "CNC.TO")