fix: harden article rich content rendering (#36) (thanks @crcatala)

tests/extract-article-text.test.ts

@@ -0,0 +1,33 @@
+import { describe, expect, it } from 'vitest';
+import type { GraphqlTweetResult } from '../src/lib/twitter-client-types.js';
+import { extractArticleText } from '../src/lib/twitter-client-utils.js';
+
+describe('extractArticleText', () => {
+  it('does not duplicate title when rich content starts with a heading', () => {
+    const result = {
+      rest_id: '1',
+      article: {
+        title: 'Hello World',
+        article_results: {
+          result: {
+            title: 'Hello World',
+            content_state: {
+              blocks: [
+                {
+                  key: '1',
+                  type: 'header-one',
+                  text: 'Hello World',
+                  entityRanges: [],
+                  inlineStyleRanges: [],
+                },
+              ],
+              entityMap: [],
+            },
+          },
+        },
+      },
+    } as GraphqlTweetResult;
+
+    expect(extractArticleText(result)).toBe('# Hello World');
+  });
+});