test(08-01): add failing tests for ZhihuCrawler

- Add test_answer_crawler.py with tests for crawl_answer()
- Add test_article_crawler.py with tests for crawl_article()
- Add test_metadata_extraction.py with tests for author/metadata parsing

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

tests/test_crawler/test_article_crawler.py

@@ -0,0 +1,66 @@
+"""Tests for Zhihu Article Crawler"""
+
+import pytest
+from unittest.mock import MagicMock, patch
+
+from kb_workflow.crawler.models import ArticleData, CrawlResult
+
+
+class TestCrawlArticle:
+    """Tests for crawl_article() method."""
+
+    def test_crawl_article_invalid_url_returns_failure(self):
+        """Test that invalid URL returns CrawlResult with success=False."""
+        from kb_workflow.crawler.zhihu_crawler import ZhihuCrawler
+
+        crawler = ZhihuCrawler(headless=True, timeout=10)
+        result = crawler.crawl_article("https://www.example.com/invalid")
+
+        assert result.success is False
+        assert result.error is not None
+        assert "Invalid" in result.error
+
+    def test_crawl_article_extracts_title(
+        self, sample_article_api_response
+    ):
+        """Test that crawl_article extracts title from API response."""
+        from kb_workflow.crawler.zhihu_crawler import ZhihuCrawler
+
+        crawler = ZhihuCrawler(headless=True, timeout=10)
+        result = crawler._parse_article_data(
+            sample_article_api_response,
+            article_id=11223344
+        )
+
+        assert isinstance(result, ArticleData)
+        assert result.title == "How to Build a Web Scraper"
+
+    def test_crawl_article_extracts_content(
+        self, sample_article_api_response
+    ):
+        """Test that crawl_article extracts content from API response."""
+        from kb_workflow.crawler.zhihu_crawler import ZhihuCrawler
+
+        crawler = ZhihuCrawler(headless=True, timeout=10)
+        result = crawler._parse_article_data(
+            sample_article_api_response,
+            article_id=11223344
+        )
+
+        assert result.content == "<p>This article explains how to build a web scraper...</p>"
+        assert result.excerpt == "This article explains how to build a web scraper..."
+
+    def test_crawl_article_contains_metadata(self, sample_article_api_response):
+        """Test that parsed article contains metadata."""
+        from kb_workflow.crawler.zhihu_crawler import ZhihuCrawler
+
+        crawler = ZhihuCrawler(headless=True, timeout=10)
+        result = crawler._parse_article_data(
+            sample_article_api_response,
+            article_id=11223344
+        )
+
+        assert result.metadata.voteup_count == 500
+        assert result.metadata.comment_count == 25
+        assert result.metadata.author is not None
+        assert result.metadata.author.name == "Jane Smith"