test: tighten okx client coverage

tests/test_okx_client.py

@@ -177,6 +177,9 @@ def test_signed_demo_request_attaches_headers():
     assert request is not None
     assert request.headers["x-simulated-trading"] == "1"
     assert request.headers["OK-ACCESS-KEY"] == "key"
+    assert request.headers["OK-ACCESS-SIGN"]
+    assert request.headers["OK-ACCESS-TIMESTAMP"]
+    assert request.headers["OK-ACCESS-PASSPHRASE"] == "passphrase"
 
 
 def test_build_contract_size_rounds_down_to_lot_size():
@@ -296,3 +299,6 @@ def test_get_positions_returns_normalized_positions():
     positions = client.get_positions(symbol="BTC-USDT-SWAP")
 
     assert positions[0].symbol == "BTC-USDT-SWAP"
+    assert positions[0].pos_side == "long"
+    assert positions[0].size == 8.0
+    assert positions[0].avg_price == 25000.0