Merge pull request #31038 from overleaf/jdt-mj-rm-chat-ide-redesign

Editor Redesign Cleanup: Chat

GitOrigin-RevId: 98f969ee84a86761466de182787443b8c9bacefd

services/web/test/frontend/shared/utils/first-character.test.ts

@@ -0,0 +1,51 @@
+import firstCharacter from '@/shared/utils/first-character'
+import { expect } from 'chai'
+import sinon from 'sinon'
+
+const CASES_ALL = [
+  // Regular ASCII characters
+  ['Hello', 'H'],
+  // Multi-byte characters (e.g. Chinese)
+  ['你好', '你'],
+  // Multi-byte characters (e.g. emojis)
+  ['😀 Smile', '😀'],
+  // Empty string
+  ['', ''],
+]
+
+const CASES_SEGMENTER = [
+  // Regional indicator symbols (e.g. flag emojis)
+  ['🇩🇰 Denmark', '🇩🇰'],
+  // ZWJ sequences (e.g. family emoji)
+  ['👩‍👩‍👧‍👦 Family', '👩‍👩‍👧‍👦'],
+  // Combining characters (e.g. accented characters)
+  ['e\u0301 Accented', 'e\u0301'],
+  ['é Accented', 'é'],
+]
+
+describe('firstCharacter', function () {
+  it('works for different types of strings', function () {
+    for (const [input, expected] of CASES_ALL) {
+      expect(firstCharacter(input)).to.equal(expected)
+    }
+    for (const [input, expected] of CASES_SEGMENTER) {
+      expect(firstCharacter(input)).to.equal(expected)
+    }
+  })
+
+  describe('when Intl.Segmenter is unavailable', function () {
+    before(function () {
+      this.segmenterStub = sinon.stub(Intl, 'Segmenter').value(undefined)
+    })
+
+    after(function () {
+      this.segmenterStub.restore()
+    })
+
+    it('falls back to the code point approach', function () {
+      for (const [input, expected] of CASES_ALL) {
+        expect(firstCharacter(input)).to.equal(expected)
+      }
+    })
+  })
+})