backport the padding option to ruby 2.2.x

lib/graphql/schema/base_64_encoder.rb

@@ -1,14 +1,38 @@
 # frozen_string_literal: true
+
+require 'base64'
+
 module GraphQL
   class Schema
     # @api private
     module Base64Encoder
       def self.encode(plaintext, nonce: false)
-        Base64.urlsafe_encode64(plaintext, padding: false)
+        Base64bp.urlsafe_encode64(plaintext, padding: false)
       end
 
       def self.decode(ciphertext, nonce: false)
-        Base64.urlsafe_decode64(ciphertext)
+        Base64bp.urlsafe_decode64(ciphertext)
+      end
+
+      # @api private
+      module Base64bp # backport from ruby v2.5 to v2.2 that has no `padding` option
+        extend Base64
+
+        module_function
+
+        def urlsafe_encode64(bin, padding:)
+          str = strict_encode64(bin).tr("+/", "-_")
+          str = str.delete("=") unless padding
+          str
+        end
+
+        def urlsafe_decode64(str)
+          str = str.tr("-_", "+/")
+          if !str.end_with?("=") && str.length % 4 != 0
+            str = str.ljust((str.length + 3) & ~3, "=")
+          end
+          strict_decode64(str)
+        end
       end
     end
   end