Improve performance of isEmojiOnlyText

ts/test-both/util/isEmojiOnlyText_test.ts

@@ -0,0 +1,28 @@
+// Copyright 2022 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+import { assert } from 'chai';
+
+import { isEmojiOnlyText } from '../../util/isEmojiOnlyText';
+
+describe('isEmojiOnlyText', () => {
+  it('returns false on empty string', () => {
+    assert.isFalse(isEmojiOnlyText(''));
+  });
+
+  it('returns false on non-emoji string', () => {
+    assert.isFalse(isEmojiOnlyText('123'));
+  });
+
+  it('returns false on mixed emoji/text string', () => {
+    assert.isFalse(isEmojiOnlyText('12😎3'));
+  });
+
+  it('returns false on mixed emoji/text string starting with emoji', () => {
+    assert.isFalse(isEmojiOnlyText('😎12😎3'));
+  });
+
+  it('returns true on all emoji string', () => {
+    assert.isTrue(isEmojiOnlyText('😎👍😀😮‍💨'));
+  });
+});