feat(signal_v2-phase3a): kis_websocket + 4 integration tests

KISWebSocket: approval_key (POST /oauth2/Approval) + H0STASP0 호가
실시간 subscribe + receive loop + exponential reconnect (1s → 2s → 4s
→ max 30s). _parse_asking_price 필드 인덱스 운영 검증 필요
(현재 가정: 마지막 2 필드가 ask_total/bid_total).

4 tests pass, 29 total.

Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>

signal_v2/tests/test_kis_websocket.py

@@ -0,0 +1,94 @@
+"""Tests for KISWebSocket."""
+import asyncio
+import json
+from unittest.mock import AsyncMock, MagicMock
+
+import httpx
+import pytest
+import respx
+
+from signal_v2.kis_websocket import KISWebSocket
+
+
+BASE_REST = "https://openapivts.koreainvestment.com:29443"
+
+
+@respx.mock
+async def test_fetch_approval_key_via_oauth_endpoint():
+    """POST /oauth2/Approval → approval_key 추출."""
+    respx.post(f"{BASE_REST}/oauth2/Approval").mock(
+        return_value=httpx.Response(200, json={"approval_key": "test-approval-key-xyz"})
+    )
+    ws = KISWebSocket(app_key="k", app_secret="s", is_virtual=True)
+    key = await ws._fetch_approval_key()
+    assert key == "test-approval-key-xyz"
+    assert ws._approval_key == "test-approval-key-xyz"
+
+
+async def test_subscribe_sends_h0stasp0_message():
+    """subscribe() → WebSocket 으로 H0STASP0 구독 메시지 전송."""
+    sent_messages = []
+    mock_ws = AsyncMock()
+    mock_ws.send = AsyncMock(side_effect=lambda m: sent_messages.append(m))
+
+    ws = KISWebSocket(app_key="k", app_secret="s", is_virtual=True)
+    ws._approval_key = "test-key"
+    ws._ws = mock_ws
+    await ws.subscribe("005930")
+    assert ws._subscriptions == {"005930"}
+    assert len(sent_messages) == 1
+    msg = json.loads(sent_messages[0])
+    assert msg["header"]["tr_type"] == "1"  # subscribe
+    assert msg["body"]["input"]["tr_id"] == "H0STASP0"
+    assert msg["body"]["input"]["tr_key"] == "005930"
+
+
+def test_parse_asking_price_extracts_bid_ask_totals():
+    """KIS raw '0|H0STASP0|001|...' → (ticker, dict).
+
+    KIS 호가 메시지 형식 — KIS 공식 spec 의 정확한 필드 인덱스 운영 검증 필요.
+    본 테스트는 implementer 의 _parse_asking_price 구현 인덱스에 맞춰서 sample 작성.
+    """
+    ws = KISWebSocket(app_key="k", app_secret="s", is_virtual=True)
+    # Build a sample raw message — implementer 가 _ASKING_TOTAL_BID/ASK 인덱스에
+    # 맞춰서 필드 배치하면 됨. 예: 마지막 2개 필드를 bid_total / ask_total 로.
+    fields = ["005930", "091500", "78500"]  # ticker, time, current_price
+    fields.extend(["0"] * 40)  # padding (KIS 의 실 필드 수 ~50개)
+    fields.append("400")  # ask_total
+    fields.append("600")  # bid_total
+    raw = f"0|H0STASP0|001|{'^'.join(fields)}"
+
+    result = ws._parse_asking_price(raw)
+    assert result is not None, "parse_asking_price returned None"
+    ticker, data = result
+    assert ticker == "005930"
+    assert "bid_total" in data
+    assert "ask_total" in data
+    assert "bid_ratio" in data
+    assert "current_price" in data
+    # bid_total=600, ask_total=400, bid_ratio=0.6
+    assert data["bid_total"] == 600
+    assert data["ask_total"] == 400
+    assert abs(data["bid_ratio"] - 0.6) < 1e-9
+
+
+async def test_reconnect_on_disconnect_with_backoff(monkeypatch):
+    """연결 끊김 → exponential backoff retry. _connect_with_backoff() 검증."""
+    sleep_calls = []
+    async def fake_sleep(s): sleep_calls.append(s)
+    monkeypatch.setattr("asyncio.sleep", fake_sleep)
+
+    ws = KISWebSocket(app_key="k", app_secret="s", is_virtual=True)
+    # Mock _connect to fail twice then succeed
+    call_count = [0]
+    async def fake_connect():
+        call_count[0] += 1
+        if call_count[0] < 3:
+            raise ConnectionError("fake disconnect")
+        return AsyncMock()
+    monkeypatch.setattr(ws, "_connect", fake_connect)
+
+    result = await ws._connect_with_backoff()
+    assert call_count[0] == 3  # 2 fails + 1 success
+    # exponential 1s, 2s
+    assert sleep_calls[:2] == [1, 2]