Fix missing spaces before and after equal signs in method definitions

actionmailer/lib/action_mailer/base.rb

@@ -530,7 +530,7 @@ def mailer_name
     # The resulting Mail::Message will have the following in its header:
     #
     #   X-Special-Domain-Specific-Header: SecretValue
-    def headers(args=nil)
+    def headers(args = nil)
       if args
         @_message.headers(args)
       else
@@ -660,7 +660,7 @@ def attachments
     #     format.html
     #   end
     #
-    def mail(headers={}, &block)
+    def mail(headers = {}, &block)
       @_mail_was_called = true
       m = @_message
 

actionmailer/lib/action_mailer/collector.rb

@@ -20,7 +20,7 @@ def any(*args, &block)
     end
     alias :all :any
 
-    def custom(mime, options={})
+    def custom(mime, options = {})
       options.reverse_merge!(content_type: mime.to_s)
       @context.formats = [mime.to_sym]
       options[:body] = block_given? ? yield : @default_render.call