Fix email signature rendering

lib/__tests__/signature-utils.test.ts

@@ -0,0 +1,39 @@
+import { describe, expect, it } from 'vitest';
+
+import {
+  appendPlainTextSignature,
+  getPlainTextSignature,
+  hasMeaningfulHtmlBody,
+} from '../signature-utils';
+
+describe('signature-utils', () => {
+  describe('getPlainTextSignature', () => {
+    it('prefers text signatures when present', () => {
+      expect(getPlainTextSignature({ textSignature: 'Regards,\nAlice', htmlSignature: '<p>Ignored</p>' })).toBe('Regards,\nAlice');
+    });
+
+    it('converts html-only signatures into plain text', () => {
+      expect(getPlainTextSignature({ htmlSignature: '<p>Alice Example<br><a href="mailto:alice@example.com">alice@example.com</a></p>' })).toBe('Alice Example\nalice@example.com');
+    });
+  });
+
+  describe('appendPlainTextSignature', () => {
+    it('appends a converted html signature to the text body', () => {
+      expect(appendPlainTextSignature('Hello there', { htmlSignature: '<p>Alice<br>Engineering</p>' })).toBe('Hello there\n\n-- \nAlice\nEngineering');
+    });
+
+    it('leaves the body untouched when no signature exists', () => {
+      expect(appendPlainTextSignature('Hello there', {})).toBe('Hello there');
+    });
+  });
+
+  describe('hasMeaningfulHtmlBody', () => {
+    it('prefers html bodies that preserve signature formatting', () => {
+      expect(hasMeaningfulHtmlBody('<div>Hello</div><br><p>Alice</p>')).toBe(true);
+    });
+
+    it('ignores minimal wrapper html with a single block', () => {
+      expect(hasMeaningfulHtmlBody('<div>Hello world</div>')).toBe(false);
+    });
+  });
+});