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

app/assets/javascripts/emoji/support/is_emoji_unicode_supported.js

@@ -7,6 +7,17 @@ function isFlagEmoji(emojiUnicode) {
   return emojiUnicode.length === 4 && cp >= flagACodePoint && cp <= flagZCodePoint;
 }
 
+// Tested on mac OS 10.12.6 and Windows 10 FCU, it renders as two separate characters
+const baseFlagCodePoint = 127987; // parseInt('1F3F3', 16)
+const rainbowCodePoint = 127752; // parseInt('1F308', 16)
+function isRainbowFlagEmoji(emojiUnicode) {
+  const characters = Array.from(emojiUnicode);
+  // Length 4 because flags are made of 2 characters which are surrogate pairs
+  return emojiUnicode.length === 4 &&
+    characters[0].codePointAt(0) === baseFlagCodePoint &&
+    characters[1].codePointAt(0) === rainbowCodePoint;
+}
+
 // Chrome <57 renders keycaps oddly
 // See https://bugs.chromium.org/p/chromium/issues/detail?id=632294
 // Same issue on Windows also fixed in Chrome 57, http://i.imgur.com/rQF7woO.png
@@ -57,9 +68,11 @@ function isPersonZwjEmoji(emojiUnicode) {
 // in `isEmojiUnicodeSupported` logic
 function checkFlagEmojiSupport(unicodeSupportMap, emojiUnicode) {
   const isFlagResult = isFlagEmoji(emojiUnicode);
+  const isRainbowFlagResult = isRainbowFlagEmoji(emojiUnicode);
   return (
     (unicodeSupportMap.flag && isFlagResult) ||
-    !isFlagResult
+    (unicodeSupportMap.rainbowFlag && isRainbowFlagResult) ||
+    (!isFlagResult && !isRainbowFlagResult)
   );
 }
 
@@ -113,6 +126,7 @@ function isEmojiUnicodeSupported(unicodeSupportMap = {}, emojiUnicode, unicodeVe
 export {
   isEmojiUnicodeSupported as default,
   isFlagEmoji,
+  isRainbowFlagEmoji,
   isKeycapEmoji,
   isSkinToneComboEmoji,
   isHorceRacingSkinToneComboEmoji,

app/assets/javascripts/emoji/support/unicode_support_map.js

 import AccessorUtilities from '../../lib/utils/accessor';
 
+const GL_EMOJI_VERSION = '0.2.0';
+
 const unicodeSupportTestMap = {
   // man, student (emojione does not have any of these yet), http://emojipedia.org/emoji-zwj-sequences/
   // occupationZwj: '\u{1F468}\u{200D}\u{1F393}',
@@ -13,6 +15,7 @@ const unicodeSupportTestMap = {
   horseRacing: '\u{1F3C7}\u{1F3FF}',
   // US flag, http://emojipedia.org/flags/
   flag: '\u{1F1FA}\u{1F1F8}',
+  rainbowFlag: '\u{1F3F3}\u{1F308}',
   // http://emojipedia.org/modifiers/
   skinToneModifier: [
     // spy_tone5
@@ -141,23 +144,31 @@ function generateUnicodeSupportMap(testMap) {
 }
 
 export default function getUnicodeSupportMap() {
-  let unicodeSupportMap;
-  let userAgentFromCache;
-
   const isLocalStorageAvailable = AccessorUtilities.isLocalStorageAccessSafe();
 
-  if (isLocalStorageAvailable) userAgentFromCache = window.localStorage.getItem('gl-emoji-user-agent');
+  let glEmojiVersionFromCache;
+  let userAgentFromCache;
+  if (isLocalStorageAvailable) {
+    glEmojiVersionFromCache = window.localStorage.getItem('gl-emoji-version');
+    userAgentFromCache = window.localStorage.getItem('gl-emoji-user-agent');
+  }
 
+  let unicodeSupportMap;
   try {
     unicodeSupportMap = JSON.parse(window.localStorage.getItem('gl-emoji-unicode-support-map'));
   } catch (err) {
     // swallow
   }
 
-  if (!unicodeSupportMap || userAgentFromCache !== navigator.userAgent) {
+  if (
+    !unicodeSupportMap ||
+    glEmojiVersionFromCache !== GL_EMOJI_VERSION ||
+    userAgentFromCache !== navigator.userAgent
+  ) {
     unicodeSupportMap = generateUnicodeSupportMap(unicodeSupportTestMap);
 
     if (isLocalStorageAvailable) {
+      window.localStorage.setItem('gl-emoji-version', GL_EMOJI_VERSION);
       window.localStorage.setItem('gl-emoji-user-agent', navigator.userAgent);
       window.localStorage.setItem('gl-emoji-unicode-support-map', JSON.stringify(unicodeSupportMap));
     }

spec/javascripts/behaviors/gl_emoji/unicode_support_map_spec.js

@@ -21,13 +21,18 @@ describe('Unicode Support Map', () => {
       });
 
       it('should call .getItem and .setItem', () => {
-        const allArgs = window.localStorage.setItem.calls.allArgs();
-
-        expect(window.localStorage.getItem).toHaveBeenCalledWith('gl-emoji-user-agent');
-        expect(allArgs[0][0]).toBe('gl-emoji-user-agent');
-        expect(allArgs[0][1]).toBe(navigator.userAgent);
-        expect(allArgs[1][0]).toBe('gl-emoji-unicode-support-map');
-        expect(allArgs[1][1]).toBe(stringSupportMap);
+        const getArgs = window.localStorage.getItem.calls.allArgs();
+        const setArgs = window.localStorage.setItem.calls.allArgs();
+
+        expect(getArgs[0][0]).toBe('gl-emoji-version');
+        expect(getArgs[1][0]).toBe('gl-emoji-user-agent');
+
+        expect(setArgs[0][0]).toBe('gl-emoji-version');
+        expect(setArgs[0][1]).toBe('0.2.0');
+        expect(setArgs[1][0]).toBe('gl-emoji-user-agent');
+        expect(setArgs[1][1]).toBe(navigator.userAgent);
+        expect(setArgs[2][0]).toBe('gl-emoji-unicode-support-map');
+        expect(setArgs[2][1]).toBe(stringSupportMap);
       });
     });
 

spec/javascripts/emoji_spec.js

 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();