Add rainbow_flag to emoji support map

Tested on the following platforms that split the emoji into separate
characters currently.
 - Windows 10 FCU
    - Chrome 62.0.3202.89
    - Firefox 57.0b14
    - MS Edge 41.16299.15.0
 - macOS 10.12.6
    - Chrome 63.0.3239.40
    - Safari 11.0.1 (12604.3.5.1.1)
    - Firefox 57.0
 - Ubuntu 16.04
    - Chromium 62.0.3202.75
    - Firefox 56.0

1 files changed, 19 insertions, 0 deletions

diff --git a/spec/javascripts/emoji_spec.js b/spec/javascripts/emoji_spec.js
index fa11c602ec3..124d91f4477 100644
--- a/spec/javascripts/emoji_spec.js
+++ b/spec/javascripts/emoji_spec.js
@@ -1,6 +1,7 @@
 import { glEmojiTag } from '~/emoji';
 import isEmojiUnicodeSupported, {
   isFlagEmoji,
+  isRainbowFlagEmoji,
   isKeycapEmoji,
   isSkinToneComboEmoji,
   isHorceRacingSkinToneComboEmoji,
@@ -217,6 +218,24 @@ describe('gl_emoji', () => {
     });
   });
 
+  describe('isRainbowFlagEmoji', () => {
+    it('should gracefully handle empty string', () => {
+      expect(isRainbowFlagEmoji('')).toBeFalsy();
+    });
+    it('should detect rainbow_flag', () => {
+      expect(isRainbowFlagEmoji('🏳🌈')).toBeTruthy();
+    });
+    it('should not detect flag_white on its\' own', () => {
+      expect(isRainbowFlagEmoji('🏳')).toBeFalsy();
+    });
+    it('should not detect rainbow on its\' own', () => {
+      expect(isRainbowFlagEmoji('🌈')).toBeFalsy();
+    });
+    it('should not detect flag_white with something else', () => {
+      expect(isRainbowFlagEmoji('🏳🔵')).toBeFalsy();
+    });
+  });
+
   describe('isKeycapEmoji', () => {
     it('should gracefully handle empty string', () => {
       expect(isKeycapEmoji('')).toBeFalsy();