test(01-03): add failing tests for configuration management

- Test KBSettings required fields (base_path, archive_path)
- Test KBSettings optional fields with defaults
- Test secret fields (hf_token, zhihu_cookie) as SecretStr
- Test missing required fields raises ValidationError
- Test get_settings returns singleton via lru_cache
- Test env vars with KB_ prefix are read

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

tests/test_pipeline/test_config.py

@@ -0,0 +1,143 @@
+"""Tests for configuration management module
+
+Tests for KBSettings and get_settings function using pydantic-settings.
+"""
+
+import os
+import pytest
+from pathlib import Path
+from unittest.mock import patch, MagicMock
+from pydantic import ValidationError as PydanticValidationError
+
+from kb_pipeline.config import KBSettings, get_settings
+
+
+class TestKBSettings:
+    """Tests for KBSettings class"""
+
+    def test_kbsettings_has_base_path_field(self):
+        """Test KBSettings has base_path field"""
+        settings = KBSettings(
+            base_path="/tmp/kb",
+            archive_path="/tmp/archive"
+        )
+        assert settings.base_path == "/tmp/kb"
+
+    def test_kbsettings_has_archive_path_field(self):
+        """Test KBSettings has archive_path field"""
+        settings = KBSettings(
+            base_path="/tmp/kb",
+            archive_path="/tmp/archive"
+        )
+        assert settings.archive_path == "/tmp/archive"
+
+    def test_kbsettings_optional_fields_have_defaults(self):
+        """Test optional fields have empty string defaults"""
+        settings = KBSettings(
+            base_path="/tmp/kb",
+            archive_path="/tmp/archive"
+        )
+        assert settings.git_root == ""
+        assert settings.git_user == ""
+        assert settings.git_email == ""
+
+    def test_kbsettings_hf_token_is_secret(self):
+        """Test hf_token is SecretStr type"""
+        from pydantic import SecretStr
+        settings = KBSettings(
+            base_path="/tmp/kb",
+            archive_path="/tmp/archive",
+            hf_token="secret_token"
+        )
+        assert isinstance(settings.hf_token, SecretStr)
+
+    def test_kbsettings_zhihu_cookie_is_secret(self):
+        """Test zhihu_cookie is SecretStr type"""
+        from pydantic import SecretStr
+        settings = KBSettings(
+            base_path="/tmp/kb",
+            archive_path="/tmp/archive",
+            zhihu_cookie="secret_cookie"
+        )
+        assert isinstance(settings.zhihu_cookie, SecretStr)
+
+    def test_kbsettings_missing_base_path_raises_error(self):
+        """Test missing base_path raises ValidationError"""
+        with pytest.raises(PydanticValidationError) as exc_info:
+            KBSettings(archive_path="/tmp/archive")
+        assert "base_path" in str(exc_info.value)
+
+    def test_kbsettings_missing_archive_path_raises_error(self):
+        """Test missing archive_path raises ValidationError"""
+        with pytest.raises(PydanticValidationError) as exc_info:
+            KBSettings(base_path="/tmp/kb")
+        assert "archive_path" in str(exc_info.value)
+
+    def test_kbsettings_can_set_optional_fields(self):
+        """Test optional fields can be set"""
+        settings = KBSettings(
+            base_path="/tmp/kb",
+            archive_path="/tmp/archive",
+            git_root="/tmp/repo",
+            git_user="testuser",
+            git_email="test@example.com"
+        )
+        assert settings.git_root == "/tmp/repo"
+        assert settings.git_user == "testuser"
+        assert settings.git_email == "test@example.com"
+
+
+class TestGetSettings:
+    """Tests for get_settings function"""
+
+    def test_get_settings_returns_kbsettings(self):
+        """Test get_settings returns KBSettings instance"""
+        with patch.dict(os.environ, {
+            "KB_BASE_PATH": "/tmp/kb",
+            "KB_ARCHIVE_PATH": "/tmp/archive"
+        }, clear=False):
+            # Clear cache before test
+            get_settings.cache_clear()
+            settings = get_settings()
+            assert isinstance(settings, KBSettings)
+
+    def test_get_settings_returns_singleton(self):
+        """Test get_settings returns same instance (cached)"""
+        with patch.dict(os.environ, {
+            "KB_BASE_PATH": "/tmp/kb",
+            "KB_ARCHIVE_PATH": "/tmp/archive"
+        }, clear=False):
+            # Clear cache before test
+            get_settings.cache_clear()
+            settings1 = get_settings()
+            settings2 = get_settings()
+            assert settings1 is settings2
+
+    def test_get_settings_uses_env_vars_with_prefix(self):
+        """Test get_settings reads from KB_ prefixed env vars"""
+        with patch.dict(os.environ, {
+            "KB_BASE_PATH": "/custom/kb",
+            "KB_ARCHIVE_PATH": "/custom/archive"
+        }, clear=False):
+            # Clear cache before test
+            get_settings.cache_clear()
+            settings = get_settings()
+            assert settings.base_path == "/custom/kb"
+            assert settings.archive_path == "/custom/archive"
+
+
+class TestKBSettingsEnvFile:
+    """Tests for KBSettings env file loading"""
+
+    def test_kbsettings_model_config_has_env_file(self):
+        """Test KBSettings model_config has env_file setting"""
+        assert hasattr(KBSettings, "model_config")
+        assert "env_file" in KBSettings.model_config
+
+    def test_kbsettings_model_config_has_env_prefix(self):
+        """Test KBSettings model_config has env_prefix setting"""
+        assert KBSettings.model_config.get("env_prefix") == "KB_"
+
+    def test_kbsettings_model_config_ignores_extra(self):
+        """Test KBSettings model_config ignores extra fields"""
+        assert KBSettings.model_config.get("extra") == "ignore"