Don't require merb-core/two-oh for multipart support. Instead, copy the code into Webrat

lib/webrat/merb_multipart_support.rb

@@ -0,0 +1,27 @@
+module Webrat
+
+  # These methods are copied from merb-core/two-oh.rb which defines new
+  # multipart_post and multipart_put methods for Merb::Test::MultipartRequestHelper.
+  # We can't require two-oh.rb because it alters Merb's own behavior, causing
+  # failing specs in Merb when Webrat is required.
+  module MerbMultipartSupport
+    def multipart_request(path, params = {}, env = {})
+      multipart = Merb::Test::MultipartRequestHelper::Post.new(params)
+      body, head = multipart.to_multipart
+      env["CONTENT_TYPE"] = head
+      env["CONTENT_LENGTH"] = body.size
+      env[:input] = StringIO.new(body)
+      request(path, env)
+    end
+
+    def multipart_post(path, params = {}, env = {})
+      env[:method] = "POST"
+      multipart_request(path, params, env)
+    end
+
+    def multipart_put(path, params = {}, env = {}, &block)
+      env[:method] = "PUT"
+      multipart_request(path, params, env)
+    end
+  end
+end

lib/webrat/merb_session.rb

@@ -4,13 +4,7 @@ require "cgi"
 gem "extlib"
 require "extlib"
 require "merb-core"
-
-begin
-  # Require Merb::Test::MultipartRequestHelper with multipart support.
-  require "merb-core/two-oh"
-rescue LoadError => e
-  # Maybe Merb got rid of this. We'll do more checking for multiparth support.
-end
+require "webrat/merb_multipart_support"
 
 # HashWithIndifferentAccess = Mash
 
@@ -18,6 +12,10 @@ module Webrat
   class MerbSession < Session #:nodoc:
     include Merb::Test::MakeRequest
 
+    # Include Webrat's own version of multipart_post/put because the officially
+    # supported methods in Merb don't perform the request correctly.
+    include MerbMultipartSupport
+
     attr_accessor :response
 
     def get(url, data, headers = nil)
@@ -44,13 +42,11 @@ module Webrat
       @response.status
     end
 
-    include Merb::Test::MultipartRequestHelper
-
     def do_request(url, data, headers, method)
-      if method == "POST" && supports_multipart? && has_file?(data)
+      if method == "POST" && has_file?(data)
         @response = multipart_post(url, data, :headers => headers)
 
-      elsif method == "PUT" && supports_multipart? && has_file?(data)
+      elsif method == "PUT" && has_file?(data)
         @response = multipart_put(url, data, :headers => headers)
 
       else
@@ -63,13 +59,6 @@ module Webrat
 
     protected
 
-      # multipart_post and multipart_put which use request to do their
-      # business through multipart_request. Older implementations of
-      # multipart_post and multipart_put use the controller directly.
-      def supports_multipart?
-        respond_to?(:multipart_request)
-      end
-
       # Recursively search the data for a file attachment.
       def has_file?(data)
         data.each do |key, value|