Expand skin tones support

- Lookup emoji by unicode that contains a skin tone modifier
- Generate skin tone variants from an emoji

lib/emoji.rb

@@ -51,11 +51,12 @@ module Emoji
 
   # Public: Find an emoji by its unicode character. Return nil if missing.
   def find_by_unicode(unicode)
-    unicodes_index[unicode]
+    unicodes_index[unicode] || unicodes_index[unicode.sub(SKIN_TONE_RE, "")]
   end
 
   private
     VARIATION_SELECTOR_16 = "\u{fe0f}".freeze
+    SKIN_TONE_RE = /[\u{1F3FB}-\u{1F3FF}]/
 
     # Characters which must have VARIATION_SELECTOR_16 to render as color emoji:
     TEXT_GLYPHS = [
@@ -70,7 +71,7 @@ module Emoji
       "\u{3030}",  # wavy dash
     ].freeze
 
-    private_constant :VARIATION_SELECTOR_16, :TEXT_GLYPHS
+    private_constant :VARIATION_SELECTOR_16, :TEXT_GLYPHS, :SKIN_TONE_RE
 
     def parse_data_file
       data = File.open(data_file, 'r:UTF-8') do |file|

lib/emoji/character.rb

@@ -43,6 +43,21 @@ module Emoji
     # Raw Unicode string for an emoji. Nil if emoji is non-standard.
     def raw() unicode_aliases.first end
 
+    # Raw Unicode strings for each skin tone variant of this emoji.
+    def raw_skin_tone_variants
+      return [] if custom? || !skin_tones?
+      raw_normalized = raw.sub("\u{fe0f}", "") # strip VARIATION_SELECTOR_16
+      idx = raw_normalized.index("\u{200d}") # detect zero-width joiner
+      SKIN_TONES.map do |modifier|
+        if idx
+          # insert modifier before zero-width joiner
+          raw_normalized[...idx] + modifier + raw_normalized[idx..]
+        else
+          raw_normalized + modifier
+        end
+      end
+    end
+
     def add_unicode_alias(str)
       unicode_aliases << str
     end
@@ -82,6 +97,16 @@ module Emoji
     end
 
     private
+    
+    SKIN_TONES = [
+      "\u{1F3FB}", # light skin tone
+      "\u{1F3FC}", # medium-light skin tone
+      "\u{1F3FD}", # medium skin tone
+      "\u{1F3FE}", # medium-dark skin tone
+      "\u{1F3FF}", # dark skin tone
+    ]
+
+    private_constant :SKIN_TONES
 
     def default_image_filename
       if custom?

test/emoji_test.rb

@@ -155,9 +155,22 @@ class EmojiTest < TestCase
   test "skin tones" do
     smiley = Emoji.find_by_alias("smiley")
     assert_equal false, smiley.skin_tones?
+    assert_equal [], smiley.raw_skin_tone_variants
 
     wave = Emoji.find_by_alias("wave")
     assert_equal true, wave.skin_tones?
+
+    wave = Emoji.find_by_unicode("\u{1f44b}\u{1f3ff}") # wave + dark skin tone
+    assert_equal "wave", wave.name
+
+    woman_with_beard = Emoji.find_by_unicode("\u{1f9d4}\u{200d}\u{2640}\u{fe0f}")
+    assert_equal [
+      "1f9d4-1f3fb-200d-2640",
+      "1f9d4-1f3fc-200d-2640",
+      "1f9d4-1f3fd-200d-2640",
+      "1f9d4-1f3fe-200d-2640",
+      "1f9d4-1f3ff-200d-2640",
+    ], woman_with_beard.raw_skin_tone_variants.map { |u| Emoji::Character.hex_inspect(u) }
   end
 
   test "no custom emojis" do