test: 提升测试覆盖率至 99%

- 新增 brand_api 测试: 覆盖所有异常处理分支
- 新增 main.py 测试: root 和 health 端点
- 新增 logging 测试: setup_logging 和 get_logger
- 新增 KolVideo __repr__ 测试
- 总计 67 个测试全部通过

Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

backend/tests/test_brand_api.py

@@ -1,6 +1,6 @@
 import pytest
 import asyncio
-from unittest.mock import AsyncMock, patch
+from unittest.mock import AsyncMock, patch, MagicMock
 import httpx
 
 from app.services.brand_api import get_brand_names, fetch_brand_name
@@ -115,3 +115,125 @@ class TestBrandAPI:
             assert len(result) == 15
             # 验证所有调用都完成了
             assert mock_fetch.call_count == 15
+
+    async def test_fetch_brand_name_200_with_nested_data(self):
+        """Test successful brand fetch with nested data structure."""
+        mock_response = MagicMock()
+        mock_response.status_code = 200
+        mock_response.json.return_value = {"data": {"name": "嵌套品牌名"}}
+
+        mock_client = AsyncMock()
+        mock_client.get.return_value = mock_response
+        mock_client.__aenter__.return_value = mock_client
+        mock_client.__aexit__.return_value = None
+
+        with patch("httpx.AsyncClient", return_value=mock_client):
+            semaphore = asyncio.Semaphore(10)
+            brand_id, brand_name = await fetch_brand_name("brand_nested", semaphore)
+
+            assert brand_id == "brand_nested"
+            assert brand_name == "嵌套品牌名"
+
+    async def test_fetch_brand_name_200_with_flat_data(self):
+        """Test successful brand fetch with flat data structure."""
+        mock_response = MagicMock()
+        mock_response.status_code = 200
+        mock_response.json.return_value = {"name": "扁平品牌名"}
+
+        mock_client = AsyncMock()
+        mock_client.get.return_value = mock_response
+        mock_client.__aenter__.return_value = mock_client
+        mock_client.__aexit__.return_value = None
+
+        with patch("httpx.AsyncClient", return_value=mock_client):
+            semaphore = asyncio.Semaphore(10)
+            brand_id, brand_name = await fetch_brand_name("brand_flat", semaphore)
+
+            assert brand_id == "brand_flat"
+            assert brand_name == "扁平品牌名"
+
+    async def test_fetch_brand_name_200_no_name(self):
+        """Test brand fetch with 200 but no name in response."""
+        mock_response = MagicMock()
+        mock_response.status_code = 200
+        mock_response.json.return_value = {"data": {"id": "123"}}  # No name field
+
+        mock_client = AsyncMock()
+        mock_client.get.return_value = mock_response
+        mock_client.__aenter__.return_value = mock_client
+        mock_client.__aexit__.return_value = None
+
+        with patch("httpx.AsyncClient", return_value=mock_client):
+            semaphore = asyncio.Semaphore(10)
+            brand_id, brand_name = await fetch_brand_name("brand_no_name", semaphore)
+
+            assert brand_id == "brand_no_name"
+            assert brand_name == "brand_no_name"  # Fallback
+
+    async def test_fetch_brand_name_request_error(self):
+        """Test brand fetch with request error."""
+        mock_client = AsyncMock()
+        mock_client.get.side_effect = httpx.RequestError("Connection failed")
+        mock_client.__aenter__.return_value = mock_client
+        mock_client.__aexit__.return_value = None
+
+        with patch("httpx.AsyncClient", return_value=mock_client):
+            semaphore = asyncio.Semaphore(10)
+            brand_id, brand_name = await fetch_brand_name("brand_error", semaphore)
+
+            assert brand_id == "brand_error"
+            assert brand_name == "brand_error"  # Fallback
+
+    async def test_fetch_brand_name_unexpected_error(self):
+        """Test brand fetch with unexpected error."""
+        mock_response = MagicMock()
+        mock_response.status_code = 200
+        mock_response.json.side_effect = ValueError("Invalid JSON")
+
+        mock_client = AsyncMock()
+        mock_client.get.return_value = mock_response
+        mock_client.__aenter__.return_value = mock_client
+        mock_client.__aexit__.return_value = None
+
+        with patch("httpx.AsyncClient", return_value=mock_client):
+            semaphore = asyncio.Semaphore(10)
+            brand_id, brand_name = await fetch_brand_name("brand_json_error", semaphore)
+
+            assert brand_id == "brand_json_error"
+            assert brand_name == "brand_json_error"  # Fallback
+
+    async def test_get_brand_names_with_exception_in_gather(self):
+        """Test that exceptions in asyncio.gather are handled."""
+        with patch("app.services.brand_api.fetch_brand_name") as mock_fetch:
+            # 第二个调用抛出异常
+            mock_fetch.side_effect = [
+                ("brand_001", "品牌A"),
+                Exception("Unexpected error"),
+                ("brand_003", "品牌C"),
+            ]
+
+            result = await get_brand_names(["brand_001", "brand_002", "brand_003"])
+
+            # 成功的应该在结果中
+            assert result["brand_001"] == "品牌A"
+            assert result["brand_003"] == "品牌C"
+            # 失败的不应该在结果中（因为是 Exception，不是 tuple）
+            assert "brand_002" not in result
+
+    async def test_fetch_brand_name_non_dict_response(self):
+        """Test brand fetch with non-dict response."""
+        mock_response = MagicMock()
+        mock_response.status_code = 200
+        mock_response.json.return_value = ["not", "a", "dict"]  # Array instead of dict
+
+        mock_client = AsyncMock()
+        mock_client.get.return_value = mock_response
+        mock_client.__aenter__.return_value = mock_client
+        mock_client.__aexit__.return_value = None
+
+        with patch("httpx.AsyncClient", return_value=mock_client):
+            semaphore = asyncio.Semaphore(10)
+            brand_id, brand_name = await fetch_brand_name("brand_array", semaphore)
+
+            assert brand_id == "brand_array"
+            assert brand_name == "brand_array"  # Fallback because response is not dict

backend/tests/test_database.py

@@ -2,6 +2,22 @@ import pytest
 from sqlalchemy import select
 
 from app.models import KolVideo
+from app.core.logging import setup_logging, get_logger
+
+
+class TestLogging:
+    """Tests for logging module."""
+
+    def test_setup_logging(self):
+        """Test logging setup."""
+        # Should not raise
+        setup_logging()
+
+    def test_get_logger(self):
+        """Test getting a logger."""
+        logger = get_logger("test")
+        assert logger is not None
+        assert logger.name == "test"
 
 
 class TestKolVideoModel:
@@ -163,3 +179,14 @@ class TestKolVideoModel:
             select(KolVideo).where(KolVideo.item_id == sample_video_data["item_id"])
         )
         assert result.scalar_one_or_none() is None
+
+    async def test_video_repr(self, test_session, sample_video_data):
+        """Test KolVideo __repr__ method."""
+        video = KolVideo(**sample_video_data)
+        test_session.add(video)
+        await test_session.commit()
+
+        repr_str = repr(video)
+        assert "KolVideo" in repr_str
+        assert sample_video_data["item_id"] in repr_str
+        assert sample_video_data["title"] in repr_str

backend/tests/test_main.py

@@ -0,0 +1,30 @@
+import pytest
+from httpx import AsyncClient, ASGITransport
+
+from app.main import app
+
+
+class TestMainApp:
+    """Tests for main app endpoints."""
+
+    @pytest.fixture
+    async def client(self):
+        """Create test client."""
+        transport = ASGITransport(app=app)
+        async with AsyncClient(transport=transport, base_url="http://test") as ac:
+            yield ac
+
+    async def test_root_endpoint(self, client):
+        """Test root endpoint returns app info."""
+        response = await client.get("/")
+        assert response.status_code == 200
+        data = response.json()
+        assert data["message"] == "KOL Insight API"
+        assert data["version"] == "1.0.0"
+
+    async def test_health_endpoint(self, client):
+        """Test health check endpoint."""
+        response = await client.get("/health")
+        assert response.status_code == 200
+        data = response.json()
+        assert data["status"] == "healthy"