Update search for colon-syntax emoji to ignore case (#3443)

* Add tests for existing replaceColons functionality

* Update to lowercase before matching short names

* Update lib_test.ts

ts/components/emoji/lib.ts

@@ -255,6 +255,7 @@ export function replaceColons(str: string) {
   return str.replace(/:[a-z0-9-_+]+:(?::skin-tone-[1-5]:)?/gi, m => {
     const [shortName = '', skinTone = '0'] = m
       .replace('skin-tone-', '')
+      .toLowerCase()
       .split(':')
       .filter(Boolean);
 

ts/test/components/emoji/lib_test.ts

@@ -0,0 +1,30 @@
+import { assert } from 'chai';
+
+import { replaceColons } from '../../../components/emoji/lib';
+
+describe('replaceColons', () => {
+  it('replaces known emoji short names between colons', () => {
+    const anEmoji = replaceColons('hello :grinning:');
+    assert.equal(anEmoji, 'hello 😀');
+  });
+
+  it('understands skin tone modifiers', () => {
+    const skinToneModifierEmoji = replaceColons('hello :wave::skin-tone-5:!');
+    assert.equal(skinToneModifierEmoji, 'hello 👋🏿!');
+  });
+
+  it('passes through strings with no colons', () => {
+    const noEmoji = replaceColons('hello');
+    assert.equal(noEmoji, 'hello');
+  });
+
+  it('ignores unknown emoji', () => {
+    const unknownEmoji = replaceColons(':Unknown: :unknown:');
+    assert.equal(unknownEmoji, ':Unknown: :unknown:');
+  });
+
+  it('converts short names to lowercase before matching them', () => {
+    const emojiWithCaps = replaceColons('hello :Grinning:');
+    assert.equal(emojiWithCaps, 'hello 😀');
+  });
+});