Use `did_you_mean` spell checker for option suggestions

Now that we require Ruby over `2.3`, we can replace the current
suggestion methods we have with tooling from the `did_you_mean` gem.

There is a small user visible change and this is that we now offer a
single suggestion for misspelled options. We are suggesting fixes during
generator invocation and during a mistyped rails server rack handler. In
both cases, if we don't make a proper prediction on the first match, we
won't do so in the second or third one, so in my mind, this is okay.

1 files changed, 2 insertions, 44 deletions

diff --git a/railties/lib/rails/command/spellchecker.rb b/railties/lib/rails/command/spellchecker.rb
index 59ccab4ea2..154358cd45 100644
--- a/railties/lib/rails/command/spellchecker.rb
+++ b/railties/lib/rails/command/spellchecker.rb
@@ -3,50 +3,8 @@
 module Rails
   module Command
     module Spellchecker # :nodoc:
-      class << self
-        def suggest(word, from:, count: 3)
-          from.sort_by { |w| levenshtein_distance(word, w) }.take(count)
-        end
-
-        private
-          # This code is based directly on the Text gem implementation.
-          # Copyright (c) 2006-2013 Paul Battley, Michael Neumann, Tim Fletcher.
-          #
-          # Returns a value representing the "cost" of transforming str1 into str2.
-          def levenshtein_distance(str1, str2) # :doc:
-            s = str1
-            t = str2
-            n = s.length
-            m = t.length
-
-            return m if (0 == n)
-            return n if (0 == m)
-
-            d = (0..m).to_a
-            x = nil
-
-            # avoid duplicating an enumerable object in the loop
-            str2_codepoint_enumerable = str2.each_codepoint
-
-            str1.each_codepoint.with_index do |char1, i|
-              e = i + 1
-
-              str2_codepoint_enumerable.with_index do |char2, j|
-                cost = (char1 == char2) ? 0 : 1
-                x = [
-                  d[j + 1] + 1, # insertion
-                  e + 1,        # deletion
-                  d[j] + cost   # substitution
-                ].min
-                d[j] = e
-                e = x
-              end
-
-              d[m] = x
-            end
-
-            x
-          end
+      def self.suggest(word, from:)
+        DidYouMean::SpellChecker.new(dictionary: from.map(&:to_s)).correct(word).first
       end
     end
   end