1 files changed, 45 insertions, 0 deletions
diff --git a/tooling/danger/emoji_checker.rb b/tooling/danger/emoji_checker.rb
new file mode 100644
index 00000000000..9d8ff93037c
--- /dev/null
+++ b/tooling/danger/emoji_checker.rb
@@ -0,0 +1,45 @@
+# frozen_string_literal: true
+
+require 'json'
+
+module Tooling
+  module Danger
+    class EmojiChecker
+      DIGESTS = File.expand_path('../../fixtures/emojis/digests.json', __dir__)
+      ALIASES = File.expand_path('../../fixtures/emojis/aliases.json', __dir__)
+
+      # A regex that indicates a piece of text _might_ include an Emoji. The regex
+      # alone is not enough, as we'd match `:foo:bar:baz`. Instead, we use this
+      # regex to save us from having to check for all possible emoji names when we
+      # know one definitely is not included.
+      LIKELY_EMOJI = /:[\+a-z0-9_\-]+:/.freeze
+
+      UNICODE_EMOJI_REGEX = %r{(
+        [\u{1F300}-\u{1F5FF}] |
+        [\u{1F1E6}-\u{1F1FF}] |
+        [\u{2700}-\u{27BF}] |
+        [\u{1F900}-\u{1F9FF}] |
+        [\u{1F600}-\u{1F64F}] |
+        [\u{1F680}-\u{1F6FF}] |
+        [\u{2600}-\u{26FF}]
+      )}x.freeze
+
+      def initialize
+        names = JSON.parse(File.read(DIGESTS)).keys +
+          JSON.parse(File.read(ALIASES)).keys
+
+        @emoji = names.map { |name| ":#{name}:" }
+      end
+
+      def includes_text_emoji?(text)
+        return false unless text.match?(LIKELY_EMOJI)
+
+        @emoji.any? { |emoji| text.include?(emoji) }
+      end
+
+      def includes_unicode_emoji?(text)
+        text.match?(UNICODE_EMOJI_REGEX)
+      end
+    end
+  end
+end